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  • TOP254YN图
  • 深圳市芯脉实业有限公司

     该会员已使用本站11年以上
  • TOP254YN 现货库存
  • 数量69850 
  • 厂家POWER 
  • 封装22+ 
  • 批号TO-220 
  • 新到现货、一手货源、当天发货、bom配单
  • QQ:1435424310QQ:1435424310 复制
  • 0755-84507451 QQ:1435424310
  • TOP254YN图
  • 香港钜辉电子有限公司

     该会员已使用本站8年以上
  • TOP254YN 现货库存
  • 数量
  • 厂家09+ 
  • 封装13 
  • 批号 
  • 原装现货
  • QQ:2293525527QQ:2293525527 复制
    QQ:78076240QQ:78076240 复制
  • 13724455578 QQ:2293525527QQ:78076240
  • TOP254YN图
  • 上海磐岳电子有限公司

     该会员已使用本站11年以上
  • TOP254YN 现货库存
  • 数量9000 
  • 厂家POWER 
  • 封装 
  • 批号2024+ 
  • 全新原装现货,全网最低价
  • QQ:3003653665QQ:3003653665 复制
    QQ:1325513291QQ:1325513291 复制
  • 021-60341766 QQ:3003653665QQ:1325513291
  • TOP254YN图
  • 上海意淼电子科技有限公司

     该会员已使用本站14年以上
  • TOP254YN 现货库存
  • 数量20000 
  • 厂家POWER 
  • 封装TO-220-7 
  • 批号23+ 
  • 原装现货热卖!请联系吴先生 13681678667
  • QQ:617677003QQ:617677003 复制
  • 15618836863 QQ:617677003
  • TOP254YN图
  • 深圳市宗天技术开发有限公司

     该会员已使用本站10年以上
  • TOP254YN 现货库存
  • 数量28600 
  • 厂家18+ 
  • 封装700 
  • 批号21+ 
  • 原装现货库存,价格优势
  • QQ:444961496QQ:444961496 复制
    QQ:2824256784QQ:2824256784 复制
  • 0755-88601327 QQ:444961496QQ:2824256784
  • TOP254YN图
  • 上海意淼电子科技有限公司

     该会员已使用本站14年以上
  • TOP254YN 现货热卖
  • 数量20000 
  • 厂家POWER 
  • 封装TO-220-7 
  • 批号23+ 
  • 原装现货热卖!请联系吴先生 13681678667
  • QQ:617677003QQ:617677003 复制
  • 15618836863 QQ:617677003
  • TOP254YN图
  • 集好芯城

     该会员已使用本站13年以上
  • TOP254YN
  • 数量16462 
  • 厂家POWER 
  • 封装TO220-6 
  • 批号最新批次 
  • 原装原厂 现货现卖
  • QQ:3008092965QQ:3008092965 复制
    QQ:3008092965QQ:3008092965 复制
  • 0755-83239307 QQ:3008092965QQ:3008092965
  • TOP254YN图
  • 深圳市晶美隆科技有限公司

     该会员已使用本站14年以上
  • TOP254YN
  • 数量11530 
  • 厂家Fairchild Semiconductor 
  • 封装TO-220-6 
  • 批号23+ 
  • 全新原装现货热卖
  • QQ:2885348317QQ:2885348317 复制
    QQ:2885348339QQ:2885348339 复制
  • 0755-83209630 QQ:2885348317QQ:2885348339
  • TOP254YN图
  • 深圳市集创讯科技有限公司

     该会员已使用本站5年以上
  • TOP254YN
  • 数量25000 
  • 厂家POWER 
  • 封装TO-220 
  • 批号24+ 
  • 原装进口正品现货,假一罚十价格优势
  • QQ:2885393494QQ:2885393494 复制
    QQ:2885393495QQ:2885393495 复制
  • 0755-83244680 QQ:2885393494QQ:2885393495
  • TOP254YN图
  • 首天国际(深圳)集团有限公司

     该会员已使用本站17年以上
  • TOP254YN
  • 数量5000 
  • 厂家Power Integrations 
  • 封装标准封装 
  • 批号2024+ 
  • 百分百原装正品,现货库存
  • QQ:528164397QQ:528164397 复制
    QQ:1318502189QQ:1318502189 复制
  • 0755-82807088 QQ:528164397QQ:1318502189
  • TOP254YN图
  • 深圳市奥伟斯科技有限公司

     该会员已使用本站7年以上
  • TOP254YN
  • 数量50000 
  • 厂家POWER 
  • 封装TO-220 
  • 批号11+ 
  • 专注POWER现货
  • QQ:3003412773QQ:3003412773 复制
    QQ:3003714016QQ:3003714016 复制
  • 0755-83254770 QQ:3003412773QQ:3003714016
  • TOP254YN图
  • 深圳市芯福林电子有限公司

     该会员已使用本站15年以上
  • TOP254YN
  • 数量65000 
  • 厂家power 
  • 封装TO-220 
  • 批号23+ 
  • 真实库存全新原装正品!代理此型号
  • QQ:2881495753QQ:2881495753 复制
  • 0755-23605827 QQ:2881495753
  • TOP254YN图
  • 深圳市华斯顿电子科技有限公司

     该会员已使用本站16年以上
  • TOP254YN
  • 数量13500 
  • 厂家POWER 
  • 封装TO-220 
  • 批号2023+ 
  • 绝对原装正品现货/优势渠道商、原盘原包原盒
  • QQ:1002316308QQ:1002316308 复制
    QQ:515102657QQ:515102657 复制
  • 深圳分公司0755-83777708“进口原装正品专供” QQ:1002316308QQ:515102657
  • TOP254YN图
  • 深圳市华斯顿电子科技有限公司

     该会员已使用本站16年以上
  • TOP254YN
  • 数量27948 
  • 厂家POWER 
  • 封装TO-220 
  • 批号2023+ 
  • 绝对原装正品全新进口深圳现货
  • QQ:1002316308QQ:1002316308 复制
    QQ:515102657QQ:515102657 复制
  • 美驻深办0755-83777708“进口原装正品专供” QQ:1002316308QQ:515102657
  • TOP254YN图
  • 深圳市隆亿诚科技有限公司

     该会员已使用本站3年以上
  • TOP254YN
  • 数量4209 
  • 厂家Power Integrations 
  • 封装TO-220-7C 
  • 批号22+ 
  • 支持检测.现货.原装价优
  • QQ:778039761QQ:778039761 复制
  • -0755-82710221 QQ:778039761
  • TOP254YN图
  • 深圳市正信鑫科技有限公司

     该会员已使用本站12年以上
  • TOP254YN
  • 数量3372 
  • 厂家Power 
  • 封装原厂封装 
  • 批号22+ 
  • 原装正品★真实库存★价格优势★欢迎来电洽谈
  • QQ:1686616797QQ:1686616797 复制
    QQ:2440138151QQ:2440138151 复制
  • 0755-22655674 QQ:1686616797QQ:2440138151
  • TOP254YN图
  • 深圳市昌和盛利电子有限公司

     该会员已使用本站11年以上
  • TOP254YN
  • 数量12568 
  • 厂家POWER 
  • 封装TO220 
  • 批号▊ NEW ▊ 
  • ▊▊【100%全新原装正品】★长期供应,量大可订!价格优惠!
  • QQ:1551106297QQ:1551106297 复制
    QQ:3059638860QQ:3059638860 复制
  • 0755-23125986 QQ:1551106297QQ:3059638860
  • TOP254YN图
  • 深圳市科美奇科技有限公司

     该会员已使用本站15年以上
  • TOP254YN
  • 数量
  • 厂家22+ 
  • 封装14-TSSOP(0.173,4.40mm 宽) 
  • 批号12560 
  • 十年资质★★稳定供货
  • QQ:578672175QQ:578672175 复制
  • 0755-83218135 QQ:578672175
  • TOP254YN图
  • 深圳市得捷芯城科技有限公司

     该会员已使用本站11年以上
  • TOP254YN
  • 数量11648 
  • 厂家POWER 
  • 封装TO-220 
  • 批号23+ 
  • 原厂可订货,技术支持,直接渠道。可签保供合同
  • QQ:3007947087QQ:3007947087 复制
    QQ:3007947087QQ:3007947087 复制
  • 0755-83061789 QQ:3007947087QQ:3007947087
  • TOP254YN图
  • 深圳市得捷芯城科技有限公司

     该会员已使用本站11年以上
  • TOP254YN
  • 数量3264 
  • 厂家POWER 
  • 封装NA/ 
  • 批号23+ 
  • 原装现货,当天可交货,原型号开票
  • QQ:3007977934QQ:3007977934 复制
    QQ:3007947087QQ:3007947087 复制
  • 0755-82546830 QQ:3007977934QQ:3007947087
  • TOP254YN图
  • 深圳市诚达吉电子有限公司

     该会员已使用本站2年以上
  • TOP254YN
  • 数量16210 
  • 厂家POWER 
  • 封装TO-220 
  • 批号2024+ 
  • 原装正品 一手现货 假一赔百
  • QQ:2881951980QQ:2881951980 复制
  • 15873513267 QQ:2881951980
  • TOP254YN图
  • 香港钜辉电子有限公司

     该会员已使用本站8年以上
  • TOP254YN
  • 数量13 
  • 厂家Power Integrations 
  • 封装TO-220-7C 
  • 批号09+ 
  • 原装现货
  • QQ:2293525527QQ:2293525527 复制
    QQ:78076240QQ:78076240 复制
  • 13724455578 QQ:2293525527QQ:78076240
  • TOP254YN图
  • 深圳市芯鹏泰科技有限公司

     该会员已使用本站8年以上
  • TOP254YN
  • 数量8635 
  • 厂家Power Integrations 
  • 封装TO-220-7C 
  • 批号23+ 
  • PMIC - AC DC 转换器,离线转换开关
  • QQ:892152356QQ:892152356 复制
  • 0755-82777852 QQ:892152356
  • TOP254YN图
  • 深圳市鹏和科技有限公司

     该会员已使用本站16年以上
  • TOP254YN
  • 数量2280 
  • 厂家Power 
  • 封装Power 
  • 批号22+ 
  • 原包原标/假一罚万/支持检测
  • QQ:604309946QQ:604309946 复制
    QQ:1261585635QQ:1261585635 复制
  • 755-83990319 QQ:604309946QQ:1261585635
  • TOP254YN图
  • 深圳市中杰盛科技有限公司

     该会员已使用本站14年以上
  • TOP254YN
  • 数量12000 
  • 厂家Power Integrations 
  • 封装TO-220-7C 
  • 批号24+ 
  • 【原装优势★★★绝对有货】
  • QQ:409801605QQ:409801605 复制
  • 0755-22968359 QQ:409801605
  • TOP254YN图
  • 深圳市恒达亿科技有限公司

     该会员已使用本站16年以上
  • TOP254YN
  • 数量3500 
  • 厂家Power Integrations 
  • 封装TO-220 
  • 批号23+ 
  • 全新原装现货特价销售!
  • QQ:867789136QQ:867789136 复制
    QQ:1245773710QQ:1245773710 复制
  • 0755-82723761 QQ:867789136QQ:1245773710
  • TOP254YN图
  • 首天国际(深圳)科技有限公司

     该会员已使用本站16年以上
  • TOP254YN
  • 数量5000 
  • 厂家Power Integrations 
  • 封装标准封装 
  • 批号2024+ 
  • 百分百原装正品,现货库存
  • QQ:528164397QQ:528164397 复制
    QQ:1318502189QQ:1318502189 复制
  • 0755-82807802 QQ:528164397QQ:1318502189
  • TOP254YN图
  • 深圳市赛尔通科技有限公司

     该会员已使用本站12年以上
  • TOP254YN
  • 数量65400 
  • 厂家POWER 
  • 封装TO220-7 
  • 批号NEW 
  • 【◆全新原装现货◆绝对价格优势◆质量保证◆】
  • QQ:1134344845QQ:1134344845 复制
    QQ:847984313QQ:847984313 复制
  • 86-0755-83536093 QQ:1134344845QQ:847984313
  • TOP254YN图
  • 上海磐岳电子有限公司

     该会员已使用本站11年以上
  • TOP254YN
  • 数量5800 
  • 厂家POWER 
  • 封装TO-220-6 
  • 批号2024+ 
  • 全新原装现货,杜绝假货。
  • QQ:3003653665QQ:3003653665 复制
    QQ:1325513291QQ:1325513291 复制
  • 021-60341766 QQ:3003653665QQ:1325513291
  • TOP254YN图
  • 深圳市欧立现代科技有限公司

     该会员已使用本站12年以上
  • TOP254YN
  • 数量5369 
  • 厂家POWER 
  • 封装TO220 
  • 批号24+ 
  • 全新原装现货,欢迎询购!
  • QQ:1950791264QQ:1950791264 复制
    QQ:221698708QQ:221698708 复制
  • 0755-83222787 QQ:1950791264QQ:221698708
  • TOP254YN图
  • 深圳市创思克科技有限公司

     该会员已使用本站2年以上
  • TOP254YN
  • 数量8000 
  • 厂家POWER 
  • 封装TO-220 
  • 批号21+ 
  • 全新原装原厂实力挺实单欢迎来撩
  • QQ:1092793871QQ:1092793871 复制
  • -0755-88910020 QQ:1092793871
  • TOP254YN图
  • 万三科技(深圳)有限公司

     该会员已使用本站2年以上
  • TOP254YN
  • 数量6500000 
  • 厂家PI 
  • 封装原厂原装 
  • 批号22+ 
  • 万三科技 秉承原装 实单可议
  • QQ:3008962483QQ:3008962483 复制
  • 0755-23763516 QQ:3008962483
  • TOP254YN图
  • 深圳市隆鑫创展电子有限公司

     该会员已使用本站15年以上
  • TOP254YN
  • 数量30000 
  • 厂家FREESCALE 
  • 封装QFP100 
  • 批号2022+ 
  • 电子元器件一站式配套服务QQ:122350038
  • QQ:2355878626QQ:2355878626 复制
    QQ:2850299242QQ:2850299242 复制
  • 0755-82812278 QQ:2355878626QQ:2850299242
  • TOP254YN图
  • 深圳市拓亿芯电子有限公司

     该会员已使用本站12年以上
  • TOP254YN
  • 数量30000 
  • 厂家POWER 
  • 封装TO-220 
  • 批号23+ 
  • 全新原装现货,价格优势
  • QQ:1774550803QQ:1774550803 复制
    QQ:2924695115QQ:2924695115 复制
  • 0755-82777855 QQ:1774550803QQ:2924695115
  • TOP254YN图
  • 上海意淼电子科技有限公司

     该会员已使用本站14年以上
  • TOP254YN
  • 数量20000 
  • 厂家POWER 
  • 封装TO220-7 
  • 批号23+ 
  • 原装现货热卖!请联系吴先生 13681678667
  • QQ:617677003QQ:617677003 复制
  • 15618836863 QQ:617677003

产品型号TOP254YN的概述

芯片TOP254YN的概述 TOP254YN是一款高性能的集成电路,主要被广泛应用于开关电源(SMPS)中。这种芯片由Power Integrations公司制造,专为电源供应设计,尤其适合用于小型、功率适配器等高效能功率转换器。TOP254YN不仅集成了多个功能模块,减少了外部元件的需求,还提高了电源的效率与可靠性。其核心设计以高频开关技术为基础,支持低损耗的电力传输,适合不同的电源应用场景。 TOP254YN在电源应用中表现出色,提升了电源效率,降低了待机功耗,并且具备多种保护功能,例如过流、过压和温度保护等,以确保电源在不同工作条件下的稳定性。从实际应用来看,TOP254YN被广泛用于消费电子、计算机及相关设备的电源设计中。 芯片TOP254YN的详细参数 TOP254YN的主要技术参数包括: - 输入电压范围:90 - 265 VAC,支持多个电压范围的输入。 - 输出功率:支...

产品型号TOP254YN的Datasheet PDF文件预览

TOP252-262  
®
TOPSwitch-HX Family  
®
Enhanced EcoSmart , Integrated Off-Line Switcher with  
Advanced Feature Set and Extended Power Range  
Product Highlights  
+
DC  
Lower System Cost, Higher Design Flexibility  
Multi-mode operation maximizes efficiency at all loads  
AC  
IN  
OUT  
-
New eSIP-7F and eSIP-7C packages  
Low thermal impedance junction-to-case (2 °C per watt)  
Low height is ideal for adapters where space is limited  
Simple mounting using a clip to aid low cost manufacturing  
Horizontal eSIP-7F package ideal for ultra low height adapter  
and monitor applications  
Extended package creepage distance from DRAIN pin to  
adjacent pin and to heat sink  
D
S
V
CONTROL  
C
TOPSwitch-HX  
X
F
No heatsink required up to 35 W using P, G and M packages  
with universal input voltage and up to 48 W at 230 VAC  
Output overvoltage protection (OVP) is user programmable for  
latching/non-latching shutdown with fast AC reset  
Allows both primary and secondary sensing  
Line undervoltage (UV) detection prevents turn-off glitches  
Line overvoltage (OV) shutdown extends line surge limit  
Accurate programmable current limit  
Optimized line feed-forward for line ripple rejection  
132 kHz frequency (254Y-258Y and all E/L packages) reduces  
transformer and power supply size  
Half frequency option for video applications  
Frequency jittering reduces EMI filter cost  
PI-4510-100206  
Figure 1. Typical Flyback Application.  
Heatsink is connected to SOURCE for low EMI  
Improved auto-restart delivers <3% of maximum power in  
short circuit and open loop fault conditions  
Accurate hysteretic thermal shutdown function automatically  
recovers without requiring a reset  
Fully integrated soft-start for minimum start-up stress  
Extended creepage between DRAIN and all other pins  
improves field reliability  
Output Power Table  
230 VAC 15%4  
85-265 VAC  
Open  
230 VAC 15%  
85-265 VAC  
Product5  
Product5  
Open  
Open  
Open  
Adapter1  
Peak3 Adapter1  
Peak3  
13 W  
13 W  
25 W  
29 W  
30 W  
40 W  
35 W  
52 W  
40 W  
64 W  
45 W  
78 W  
50 W  
92 W  
Adapter1  
Adapter1  
Frame2  
Frame2  
Frame2  
Frame2  
TOP252EN  
TOP253EN  
TOP254EN/YN  
TOP255EN/YN  
TOP255LN  
TOP256EN/YN7  
TOP256LN  
TOP257EN/YN  
TOP257LN  
TOP258EN/YN  
TOP258LN  
TOP259EN/YN  
TOP259LN  
TOP260EN/YN  
TOP260LN  
TOP261EN/YN  
TOP261LN  
10 W  
21 W  
21 W  
43 W  
6 W  
13 W  
20 W  
26 W  
26 W  
40 W  
40 W  
55 W  
55 W  
70 W  
70 W  
80 W  
80 W  
93 W  
93 W  
118 W  
118 W  
118 W  
118 W  
13 W  
29 W  
43 W  
57 W  
57 W  
86 W  
64 W  
119 W  
78 W  
148 W  
92 W  
171 W  
120 W  
200 W  
140 W  
254 W  
177 W  
254 W  
177 W  
TOP252PN/GN  
TOP252MN  
21 W  
6 W  
21 W  
9 W  
15 W  
10 W  
15 W  
20 W  
22 W  
26 W  
30 W  
35 W  
30 W  
62 W  
TOP253PN/GN  
TOP253MN  
38 W  
9 W  
43 W  
40 W  
81 W  
15 W  
16 W  
19 W  
21 W  
25 W  
29 W  
25 W  
28 W  
30 W  
34 W  
41 W  
48 W  
40 W  
81 W  
60 W  
60 W  
119 W  
88 W  
TOP254PN/GN  
TOP254MN  
47 W  
11 W  
62 W  
85 W  
85 W  
157 W  
105 W  
195 W  
122 W  
238 W  
162 W  
275 W  
190 W  
333 W  
244 W  
333 W  
244 W  
TOP255PN/GN  
TOP255MN  
54 W  
13 W  
81 W  
105 W  
105 W  
128 W  
128 W  
147 W  
147 W  
177 W  
177 W  
177 W  
177 W  
TOP256PN/GN  
TOP256MN  
63 W  
15 W  
98 W  
TOP257PN/GN  
TOP257MN  
70 W  
19 W  
119 W  
TOP258PN/GN  
TOP258MN  
77 W  
22 W  
140 W  
TOP262EN6  
TOP262LN6  
Table 1.  
Output Power Table. (for notes see page 2).  
www.powerint.com  
January 2009  
TOP252-262  
EcoSmart®– Energy Efficient  
Energy efficient over entire load range  
No-load consumption  
Less than 200 mW at 230 VAC  
Standby power for 1 W input  
>600 mW output at 110 VAC input  
>500 mW output at 265 VAC input  
Y Package Option for TOP259-261  
In order to improve noise-immunity on large TOPSwitch-HX  
Y package parts, the F pin has been removed (TOP259-261YN  
are fixed at 66 kHz switching frequency) and replaced with a  
SIGNAL GROUND (G) pin. This pin acts as a low noise path for  
the C pin capacitor and the X pin resistor. It is only required for  
the TOP259-261YN package parts.  
Description  
TOPSwitch-HX cost effectively incorporates a 700 V power  
MOSFET, high voltage switched current source, PWM control,  
oscillator, thermal shutdown circuit, fault protection and other  
control circuitry onto a monolithic device.  
+
DC  
AC  
IN  
OUT  
-
D
S
V
Notes for Table 1:  
1. Minimum continuous power in a typical non-ventilated  
enclosed adapter measured at +50 °C ambient. Use of an  
external heat sink will increase power capability.  
2. Minimum continuous power in an open frame design at  
+50 °C ambient.  
CONTROL  
C
TOPSwitch-HX  
X
G
3. Peak power capability in any design at +50 °C ambient.  
4. 230 VAC or 110/115 VAC with doubler.  
PI-4973-122607  
5. Packages: P: DIP-8C, G: SMD-8C, M: SDIP-10C,  
Y: TO-220-7C, E: eSIP-7C, L: eSIP-7F.  
Figure 2. Typical Flyback Application TOP259YN, TOP260YN and TOP261YN.  
See part ordering information.  
6. TOP261 and TOP262 have the same current limit set point. In  
some applications TOP262 may run cooler than TOP261 due  
to a lower RDS(ON) for the larger device.  
7. TOP256E package parts are available with Green (Halogen  
Free) mold compound. See Part Ordering Information on  
page 47. Parametrically green material encapsulated E  
package parts are identical to non-green parts.  
2
Rev. F 01/09  
www.powerint.com  
TOP252-262  
Section List  
Functional Block Diagram ....................................................................................................................................... 4  
Pin Functional Description ...................................................................................................................................... 6  
TOPSwitch-HX Family Functional Description ....................................................................................................... 7  
CONTROL (C) Pin Operation.................................................................................................................................... 8  
Oscillator and Switching Frequency.......................................................................................................................... 8  
Pulse Width Modulator ............................................................................................................................................ 9  
Maximum Load Cycle .............................................................................................................................................. 9  
Error Amplifier .......................................................................................................................................................... 9  
On-Chip Current Limit with External Programmability ............................................................................................... 9  
Line Under-Voltage Detection (UV).......................................................................................................................... 10  
Line Overvoltage Shutdown (OV)............................................................................................................................ 11  
Hysteretic or Latching Output Overvoltage Protection (OVP)................................................................................... 11  
Line Feed-Forward with DCMAX Reduction .............................................................................................................. 13  
Remote ON/OFF and Synchronization.................................................................................................................... 13  
Soft-Start............................................................................................................................................................... 13  
Shutdown/Auto-Restart ......................................................................................................................................... 13  
Hysteretic Over-Temperature Protection................................................................................................................. 13  
Bandgap Reference ............................................................................................................................................... 13  
High-Voltage Bias Current Source.......................................................................................................................... 13  
Typical Uses of FREQUENCY (F) Pin ...................................................................................................................... 15  
Typical Uses of VOLTAGE MONITOR (V) and EXTERNAL CURRENT LIMIT (X) Pins .......................................... 16  
Typical Uses of MULTI-FUNCTION (M) Pin ........................................................................................................... 18  
Application Examples .............................................................................................................................................. 21  
A High Efficiency, 35 W, Dual Output – Universal Input Power Supply..................................................................... 21  
A High Efficiency, 1500 W, 250-380 VDC Input Power Supply................................................................................ 22  
A High Efficiency, 20 W Continuous – 80 W Peak, Universal Input Power Supply ................................................... 23  
A High Efficiency, 65 W, Universal Input Power Supply ........................................................................................... 24  
Key Application Considerations .............................................................................................................................. 25  
TOPSwitch-HX vs.TOPSwitch-GX....................................................................................................................... . 25  
TOPSwitch-HX Design Considerations .................................................................................................................. 26  
TOPSwitch-HX Layout Considerations................................................................................................................... 27  
Quick Design Checklist .......................................................................................................................................... 31  
Design Tools .......................................................................................................................................................... 31  
Product Specifications and Test Conditions .......................................................................................................... 32  
Typical Performance Characteristics .................................................................................................................... 39  
Package Outlines .................................................................................................................................................... 43  
Part Ordering Information ........................................................................................................................................ 47  
3
www.powerint.com  
Rev. F 01/09  
TOP252-262  
VC  
0
1
CONTROL (C)  
DRAIN (D)  
ZC  
INTERNAL  
SUPPLY  
-
SHUNT REGULATOR/  
ERROR AMPLIFIER  
+
-
+
SOFT START  
5.8 V  
4.8 V  
-
5.8 V  
+
INTERNAL UV  
COMPARATOR  
KPS(UPPER)  
-
IFB  
+
V
I (LIMIT)  
CURRENT  
LIMIT  
ADJUST  
KPS(LOWER)  
-
÷ 16  
ON/OFF  
+
SHUTDOWN/  
AUTO-RESTART  
CURRENT LIMIT  
COMPARATOR  
VBG + VT  
STOP LOGIC  
HYSTERETIC  
THERMAL  
MULTI-  
FUNCTION (M)  
SOURCE (S)  
CONTROLLED  
SHUTDOWN  
TURN-ON  
GATE DRIVER  
STOP SOFT  
V
OVP OV/  
UV  
START  
DMAX  
LINE  
SENSE  
OSCILLATOR  
WITH JITTER  
DCMAX  
DCMAX  
CLOCK  
F REDUCTION  
S
R
Q
LEADING  
EDGE  
BLANKING  
F REDUCTION  
SOFT START  
IFB  
IPS(UPPER)  
IPS(LOWER)  
PWM  
OFF  
KPS(UPPER)  
KPS(LOWER)  
SOURCE (S)  
PI-4508-120307  
Figure 3a. Functional Block Diagram (P and G Packages).  
VC  
0
1
CONTROL (C)  
ZC  
DRAIN (D)  
INTERNAL  
SUPPLY  
-
SHUNT REGULATOR/  
ERROR AMPLIFIER  
+
-
+
SOFT START  
5.8 V  
4.8 V  
-
5.8 V  
+
INTERNAL UV  
COMPARATOR  
KPS(UPPER)  
-
IFB  
+
V
I (LIMIT)  
CURRENT  
LIMIT  
ADJUST  
KPS(LOWER)  
-
÷ 16  
ON/OFF  
+
SHUTDOWN/  
AUTO-RESTART  
EXTERNAL  
CURRENT  
LIMIT (X)  
CURRENT LIMIT  
COMPARATOR  
VBG + VT  
STOP LOGIC  
VOLTAGE  
MONITOR (V)  
HYSTERETIC  
THERMAL  
SOURCE (S)  
1 V  
SHUTDOWN  
CONTROLLED  
TURN-ON  
GATE DRIVER  
STOP SOFT  
V
OVP OV/  
START  
UV  
DMAX  
LINE  
SENSE  
OSCILLATOR  
WITH JITTER  
DCMAX  
DCMAX  
CLOCK  
S
R
Q
F REDUCTION  
LEADING  
EDGE  
BLANKING  
F REDUCTION  
SOFT START  
IFB  
OFF  
PWM  
KPS(UPPER)  
KPS(LOWER)  
IPS(UPPER)  
IPS(LOWER)  
SOURCE (S)  
PI-4643-082907  
Figure 3b. Functional Block Diagram (M Package).  
4
Rev. F 01/09  
www.powerint.com  
TOP252-262  
VC  
0
1
CONTROL (C)  
DRAIN (D)  
ZC  
INTERNAL  
SUPPLY  
-
SHUNT REGULATOR/  
ERROR AMPLIFIER  
+
-
+
SOFT START  
5.8 V  
4.8 V  
-
5.8 V  
+
INTERNAL UV  
COMPARATOR  
KPS(UPPER)  
-
IFB  
+
V
I (LIMIT)  
CURRENT  
LIMIT  
ADJUST  
KPS(LOWER)  
-
÷ 16  
ON/OFF  
+
SHUTDOWN/  
AUTO-RESTART  
EXTERNAL  
CURRENT  
LIMIT (X)  
CURRENT LIMIT  
COMPARATOR  
VBG + VT  
STOP LOGIC  
VOLTAGE  
MONITOR (V)  
HYSTERETIC  
THERMAL  
SOURCE (S)  
CONTROLLED  
1 V  
SHUTDOWN  
TURN-ON  
GATE DRIVER  
STOP SOFT  
V
OVP OV/  
START  
UV  
DMAX  
LINE  
SENSE  
OSCILLATOR  
WITH JITTER  
DCMAX  
66k/132k  
DCMAX  
CLOCK  
S
R
Q
F REDUCTION  
LEADING  
EDGE  
BLANKING  
FREQUENCY  
(F)  
F REDUCTION  
SOFT START  
IFB  
OFF  
PWM  
KPS(UPPER)  
KPS(LOWER)  
IPS(UPPER)  
IPS(LOWER)  
SOURCE (S)  
PI-4511-082907  
Figure 3c. Functional Block Diagram (TOP254-258 YN Package and all eSIP Packages).  
VC  
0
1
CONTROL (C)  
ZC  
DRAIN (D)  
INTERNAL  
SUPPLY  
-
SHUNT REGULATOR/  
ERROR AMPLIFIER  
+
+
SOFT START  
5.8 V  
4.8 V  
-
-
5.8 V  
+
INTERNAL UV  
COMPARATOR  
KPS(UPPER)  
-
IFB  
+
V
I (LIMIT)  
CURRENT  
LIMIT  
ADJUST  
KPS(LOWER)  
-
÷ 16  
ON/OFF  
+
SHUTDOWN/  
AUTO-RESTART  
EXTERNAL  
CURRENT  
LIMIT (X)  
CURRENT LIMIT  
COMPARATOR  
VBG + VT  
STOP LOGIC  
VOLTAGE  
MONITOR (V)  
HYSTERETIC  
THERMAL  
SOURCE (S)  
1 V  
SHUTDOWN  
CONTROLLED  
TURN-ON  
GATE DRIVER  
STOP SOFT  
V
OVP OV/  
START  
UV  
DMAX  
LINE  
SENSE  
OSCILLATOR  
WITH JITTER  
DCMAX  
DCMAX  
CLOCK  
S
R
Q
F REDUCTION  
LEADING  
EDGE  
BLANKING  
SOURCE (S)  
F REDUCTION  
SOFT START  
IFB  
OFF  
PWM  
KPS(UPPER)  
KPS(LOWER)  
IPS(UPPER)  
IPS(LOWER)  
SIGNAL  
GROUND (G)  
PI-4974-122607  
Figure 3d. Functional Block Diagram TOP259YN, TOP260YN, TOP261YN.  
5
www.powerint.com  
Rev. F 01/09  
TOP252-262  
Pin Functional Description  
VOLTAGE MONITOR (V) Pin (Y & M package only):  
Input for OV, UV, line feed forward with DCMAX reduction, output  
overvoltage protection (OVP), remote ON/OFF and device reset.  
A connection to the SOURCE pin disables all functions on this pin.  
DRAIN (D) Pin:  
High-voltage power MOSFET DRAIN pin. The internal start-up  
bias current is drawn from this pin through a switched high-  
voltage current source. Internal current limit sense point for  
drain current.  
MULTI-FUNCTION (M) Pin (P & G packages only):  
This pin combines the functions of the VOLTAGE MONITOR (V)  
and EXTERNAL CURRENT LIMIT (X) pins of the Y package into  
one pin. Input pin for OV, UV, line feed forward with DCMAX  
CONTROL (C) Pin:  
Error amplifier and feedback current input pin for duty cycle  
control. Internal shunt regulator connection to provide internal  
bias current during normal operation. It is also used as the  
connection point for the supply bypass and auto-restart/  
compensation capacitor.  
VUV = IUV × RLS + VV (IV = IUV  
VOV = IOV × RLS + VV (IV = IOV  
)
)
+
For RLS = 4 M7  
4 M7  
RLS  
VUV = 102.8 VDC  
VOV = 451 VDC  
EXTERNAL CURRENT LIMIT (X) Pin (Y, M, E and L package):  
Input pin for external current limit adjustment and remote  
ON/OFF. A connection to SOURCE pin disables all functions  
on this pin.  
DCMAX@100 VDC = 76%  
DCMAX@375 VDC = 41%  
DC  
Input  
Voltage  
D
S
V
CONTROL  
C
For RIL = 12 k7  
ILIMIT = 61%  
X
E Package (eSIP-7C)  
Y Package (TO-220-7C)  
Note: Y package for TOP259-261  
See Figure 55b for  
other resistor values  
(RIL) to select different  
ILIMIT values.  
RIL  
12 k7  
-
Exposed Pad  
(Hidden)  
Internally  
Connected to  
SOURCE Pin  
Figure 5. TOP254-258 Y and All M/E/L Package Line Sense and Externally Set  
Current Limit.  
VUV = IUV × RLS + VV (IV = IUV  
VOV = IOV × RLS + VV (IV = IOV  
)
)
Tab Internally  
Connected to  
SOURCE Pin  
+
1 2 3 4 5  
V X C F S  
7
D
For RLS = 4 M7  
4 M7  
RLS  
L Package (eSIP-7F)  
VUV = 102.8 VDC  
VOV = 451 VDC  
DCMAX@100 VDC = 76%  
DCMAX@375 VDC = 41%  
DC  
Input  
Voltage  
D
S
V
1 2 3 4 5  
V X C SG  
7
D
CONTROL  
C
Lead Bend  
For RIL = 12 k7  
ILIMIT = 61%  
Outward from Drawing  
(Refer to eSIP-7F Package  
Outline Drawing)  
X
G
1 2 3 4 5  
V X C F S  
7
D
See Figure 55b for  
other resistor values  
(RIL) to select different  
ILIMIT values.  
RIL  
12 k7  
M Package  
-
Y Package (TO-220-7C)  
Note: Y package for TOP254-258  
V
S
10  
9
1
2
3
Figure 6. TOP259-261 Y Package Line Sense and External Current Limit.  
S
S
S
X
C
8
7
+
VUV = IUV × RLS + VM (IM = IUV  
VOV = IOV × RLS + VM (IM = IOV  
)
)
5
6
D
S
Tab Internally  
Connected to  
SOURCE Pin  
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
P and G Package  
RLS  
4 M7  
M
C
S
S
1
2
8
7
DC  
Input  
Voltage  
DCMAX@100 VDC = 76%  
DCMAX@375 VDC = 41%  
D
S
M
6
5
S
S
1 2 3 4 5  
V X C S F  
7
CONTROL  
C
D
4
D
PI-4644-091108  
-
PI-4712-120307  
Figure 4. Pin Configuration (Top View).  
Figure 7. P/G Package Line Sense.  
6
Rev. F 01/09  
www.powerint.com  
TOP252-262  
Auto-Restart  
+
78  
For RIL = 12 k7  
ILIMIT = 61%  
Slope = PWM Gain  
(constant over load range)  
For RIL = 19 k7  
ILIMIT = 37%  
DC  
Input  
Voltage  
See Figure 55b for other  
resistor values (RIL) to  
select different ILIMIT values.  
D
S
M
CONTROL  
C
RIL  
CONTROL  
Current  
-
PI-4713-021308  
100  
55  
Figure 8. P/G Package Externally Set Current Limit.  
reduction, output overvoltage protection (OVP), external current  
limit adjustment, remote ON/OFF and device reset. A  
connection to SOURCE pin disables all functions on this pin  
and makes TOPSwitch-HX operate in simple three terminal  
mode (like TOPSwitch-II).  
25  
CONTROL  
Current  
FREQUENCY (F) Pin (TOP254-258Y, and all E and L packages):  
Input pin for selecting switching frequency 132 kHz if connected  
to SOURCE pin and 66 kHz if connected to CONTROL pin.  
The switching frequency is internally set for fixed 66 kHz  
operation in the P, G, M package and TOP259YN, TOP260YN  
and TOP261YN.  
Full Frequency Mode  
132  
66  
Low  
Frequency  
Mode  
Variable  
Frequency  
Mode  
SIGNAL GROUND (G) Pin (TOP259YN, TOP260YN &  
TOP261YN only):  
Return for C pin capacitor and X pin resistor.  
Multi-Cycle  
Modulation  
Jitter  
30  
SOURCE (S) Pin:  
Output MOSFET source connection for high voltage power  
return. Primary side control circuit common and reference point.  
CONTROL  
IC03 ICOFF  
ICD1 IB  
IC01  
IC02  
Current  
PI-4645-041107  
Figure 9. Control Pin Characteristics (Multi-Mode Operation).  
TOPSwitch-HX Family Functional Description  
Like TOPSwitch-GX, TOPSwitch-HX is an integrated switched  
mode power supply chip that converts a current at the control  
input to a duty cycle at the open drain output of a high voltage  
power MOSFET. During normal operation the duty cycle of the  
power MOSFET decreases linearly with increasing CONTROL  
pin current as shown in Figure 9.  
two terminals, VOLTAGE-MONITOR and EXTERNAL CURRENT  
LIMIT (available in M package) or one terminal MULTI-FUNCTION  
(available in P and G package) have been used to implement  
some of the new functions. These terminals can be connected  
to the SOURCE pin to operate the TOPSwitch-HX in a  
TOPSwitch-like three terminal mode. However, even in this three  
terminal mode, the TOPSwitch-HX offers many transparent  
features that do not require any external components:  
In addition to the three terminal TOPSwitch features, such as  
the high voltage start-up, the cycle-by-cycle current limiting,  
loop compensation circuitry, auto-restart and thermal  
shutdown, the TOPSwitch-HX incorporates many additional  
functions that reduce system cost, increase power supply  
performance and design flexibility. A patented high voltage  
CMOS technology allows both the high-voltage power MOSFET  
and all the low voltage control circuitry to be cost effectively  
integrated onto a single monolithic chip.  
1. A fully integrated 17 ms soft-start significantly reduces or  
eliminates output overshoot in most applications by sweeping  
both current limit and frequency from low to high to limit the  
peak currents and voltages during start-up.  
2. A maximum duty cycle (DCMAX) of 78% allows smaller input  
storage capacitor, lower input voltage requirement and/or  
higher power capability.  
3. Multi-mode operation optimizes and improves the power  
supply efficiency over the entire load range while maintaining  
good cross regulation in multi-output supplies.  
Three terminals, FREQUENCY, VOLTAGE-MONITOR, and  
EXTERNAL CURRENT LIMIT (available in Y and E/L packages),  
7
www.powerint.com  
Rev. F 01/09  
TOP252-262  
4. Switching frequency of 132 kHz reduces the transformer size  
with no noticeable impact on EMI.  
5. Frequency jittering reduces EMI in the full frequency mode at  
high load condition.  
6. Hysteretic over-temperature shutdown ensures automatic  
recovery from thermal fault. Large hysteresis prevents circuit  
board overheating.  
7. Packages with omitted pins and lead forming provide large  
drain creepage distance.  
8. Reduction of the auto-restart duty cycle and frequency to  
improve the protection of the power supply and load during  
open loop fault, short circuit, or loss of regulation.  
9. Tighter tolerances on I2f power coefficient, current limit  
reduction, PWM gain and thermal shutdown threshold.  
current source connected internally between the DRAIN and  
CONTROL pins. When the CONTROL pin voltage VC reaches  
approximately 5.8 V, the control circuitry is activated and the  
soft-start begins. The soft-start circuit gradually increases the  
drain peak current and switching frequency from a low starting  
value to the maximum drain peak current at the full frequency  
over approximately 17 ms. If no external feedback/supply  
current is fed into the CONTROL pin by the end of the soft-start,  
the high voltage current source is turned off and the CONTROL  
pin will start discharging in response to the supply current  
drawn by the control circuitry. If the power supply is designed  
properly, and no fault condition such as open loop or shorted  
output exists, the feedback loop will close, providing external  
CONTROL pin current, before the CONTROL pin voltage has  
had a chance to discharge to the lower threshold voltage of  
approximately 4.8 V (internal supply undervoltage lockout  
threshold). When the externally fed current charges the  
CONTROL pin to the shunt regulator voltage of 5.8 V, current in  
excess of the consumption of the chip is shunted to SOURCE  
through an NMOS current mirror as shown in Figure 3. The  
output current of that NMOS current mirror controls the duty  
cycle of the power MOSFET to provide closed loop regulation.  
The shunt regulator has a finite low output impedance ZC that  
sets the gain of the error amplifier when used in a primary  
feedback configuration. The dynamic impedance ZC of the  
CONTROL pin together with the external CONTROL pin  
capacitance sets the dominant pole for the control loop.  
The VOLTAGE-MONITOR (V) pin is usually used for line sensing  
by connecting a 4 MΩ resistor from this pin to the rectified DC  
high voltage bus to implement line overvoltage (OV), under-  
voltage (UV) and dual-slope line feed-forward with DCMAX  
reduction. In this mode, the value of the resistor determines the  
OV/UV thresholds and the DCMAX is reduced linearly with a dual  
slope to improve line ripple rejection. In addition, it also  
provides another threshold to implement the latched and  
hysteretic output overvoltage protection (OVP). The pin can  
also be used as a remote ON/OFF using the IUV threshold.  
The EXTERNAL CURRENT LIMIT (X) pin can be used to reduce  
the current limit externally to a value close to the operating peak  
current, by connecting the pin to SOURCE through a resistor.  
This pin can also be used as a remote ON/OFF input.  
When a fault condition such as an open loop or shorted output  
prevents the flow of an external current into the CONTROL pin,  
the capacitor on the CONTROL pin discharges towards 4.8 V.  
At 4.8 V, auto-restart is activated, which turns the output  
MOSFET off and puts the control circuitry in a low current  
standby mode. The high-voltage current source turns on and  
charges the external capacitance again. A hysteretic internal  
supply undervoltage comparator keeps VC within a window of  
typically 4.8 V to 5.8 V by turning the high-voltage current  
source on and off as shown in Figure 11. The auto-restart  
circuit has a divide-by-sixteen counter, which prevents the  
output MOSFET from turning on again until sixteen discharge/  
charge cycles have elapsed. This is accomplished by enabling  
the output MOSFET only when the divide-by-sixteen counter  
reaches the full count (S15). The counter effectively limits  
TOPSwitch-HX power dissipation by reducing the auto-restart  
duty cycle to typically 2%. Auto-restart mode continues until  
output voltage regulation is again achieved through closure of  
the feedback loop.  
For the P and G package the VOLTAGE-MONITOR and  
EXTERNAL CURRENT LIMIT pin functions are combined on  
one MULTI-FUNCTION (M) pin. However, some of the functions  
become mutually exclusive.  
The FREQUENCY (F) pin in the TOP254-258 Y and E/L packages  
set the switching frequency in the full frequency PWM mode to  
the default value of 132 kHz when connected to SOURCE pin. A  
half frequency option of 66 kHz can be chosen by connecting  
this pin to the CONTROL pin instead. Leaving this pin open is  
not recommended. In the P, G and M packages and the  
TOP259-261 Y packages, the frequency is set internally at  
66 kHz in the full frequency PWM mode.  
CONTROL (C) Pin Operation  
The CONTROL pin is a low impedance node that is capable of  
receiving a combined supply and feedback current. During  
normal operation, a shunt regulator is used to separate the  
feedback signal from the supply current. CONTROL pin voltage  
VC is the supply voltage for the control circuitry including the  
MOSFET gate driver. An external bypass capacitor closely  
connected between the CONTROL and SOURCE pins is  
required to supply the instantaneous gate drive current. The  
total amount of capacitance connected to this pin also sets the  
auto-restart timing as well as control loop compensation.  
When rectified DC high voltage is applied to the DRAIN pin  
during start-up, the MOSFET is initially off, and the CONTROL  
pin capacitor is charged through a switched high voltage  
Oscillator and Switching Frequency  
The internal oscillator linearly charges and discharges an  
internal capacitance between two voltage levels to create a  
triangular waveform for the timing of the pulse width modulator.  
This oscillator sets the pulse width modulator/current limit latch  
at the beginning of each cycle.  
The nominal full switching frequency of 132 kHz was chosen to  
minimize transformer size while keeping the fundamental EMI  
frequency below 150 kHz. The FREQUENCY pin (available only  
in TOP254-258 Y and E, L packages), when shorted to the  
CONTROL pin, lowers the full switching frequency to 66 kHz  
8
Rev. F 01/09  
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TOP252-262  
packages). Duty cycle is reduced from DCMAX through the  
reduction of the on-time when IC is increased beyond IB. This  
operation is identical to the PWM control of all other TOPSwitch  
families. TOPSwitch-HX only operates in this mode if the cycle-  
by-cycle peak drain current stays above kPS(UPPER)*ILIMIT(set),  
where kPS(UPPER) is 55% (typical) and ILIMIT(set) is the current limit  
externally set via the X or M pin.  
fOSC  
+
Switching  
Frequency  
fOSC  
-
4 ms  
Variable Frequency PWM mode: When peak drain current is  
lowered to kPS(UPPER)* ILIMIT(set) as a result of power supply load  
reduction, the PWM modulator initiates the transition to variable  
frequency PWM mode, and gradually turns off frequency jitter.  
VDRAIN  
Time  
In this mode, peak drain current is held constant at kPS(UPPER)  
LIMIT(set) while switching frequency drops from the initial full  
frequency of fOSC (132 kHz or 66 kHz) towards the minimum  
*
I
Figure 10. Switching Frequency Jitter (Idealized VDRAIN Waveforms).  
frequency of fMCM(MIN) (30 kHz typical). Duty cycle reduction is  
accomplished by extending the off-time.  
(half frequency), which may be preferable in some cases such  
as noise sensitive video applications or a high efficiency  
standby mode. Otherwise, the FREQUENCY pin should be  
connected to the SOURCE pin for the default 132 kHz. In the  
M, P and G packages and the TOP259-261 Y package option,  
the full frequency PWM mode is set at 66 kHz, for higher  
efficiency and increased output power in all applications.  
Low Frequency PWM mode: When switching frequency  
reaches fMCM(MIN) (30 kHz typical), the PWM modulator starts to  
transition to low frequency mode. In this mode, switching  
frequency is held constant at fMCM(MIN) and duty cycle is reduced,  
similar to the full frequency PWM mode, through the reduction  
of the on-time. Peak drain current decreases from the initial  
value of kPS(UPPER)* ILIMIT(set) towards the minimum value of  
To further reduce the EMI level, the switching frequency in the  
full frequency PWM mode is jittered (frequency modulated) by  
approximately 2.5 kHz for 66 kHz operation or 5 kHz for  
132 kHz operation at a 250 Hz (typical) rate as shown in  
Figure 10. The jitter is turned off gradually as the system is  
entering the variable frequency mode with a fixed peak drain  
current.  
k
PS(LOWER)*ILIMIT(set), where kPS(LOWER) is 25% (typical) and ILIMIT(set) is  
the current limit externally set via the X or M pin.  
Multi-Cycle-Modulation mode: When peak drain current is  
lowered to kPS(LOWER)*ILIMIT(set), the modulator transitions to multi-  
cycle-modulation mode. In this mode, at each turn-on, the  
modulator enables output switching for a period of TMCM(MIN) at  
the switching frequency of fMCM(MIN) (4 or 5 consecutive pulses at  
30 kHz) with the peak drain current of kPS(LOWER)*ILIMIT(set), and  
stays off until the CONTROL pin current falls below IC(OFF). This  
mode of operation not only keeps peak drain current low but  
also minimizes harmonic frequencies between 6 kHz and  
30 kHz. By avoiding transformer resonant frequency this way,  
all potential transformer audible noises are greatly supressed.  
Pulse Width Modulator  
The pulse width modulator implements multi-mode control by  
driving the output MOSFET with a duty cycle inversely  
proportional to the current into the CONTROL pin that is in  
excess of the internal supply current of the chip (see Figure 9).  
The feedback error signal, in the form of the excess current, is  
filtered by an RC network with a typical corner frequency of  
7 kHz to reduce the effect of switching noise in the chip supply  
current generated by the MOSFET gate driver.  
Maximum Duty Cycle  
The maximum duty cycle, DCMAX, is set at a default maximum  
value of 78% (typical). However, by connecting the VOLTAGE-  
MONITOR or MULTI-FUNCTION pin (depending on the  
package) to the rectified DC high voltage bus through a resistor  
with appropriate value (4 MΩ typical), the maximum duty cycle  
can be made to decrease from 78% to 40% (typical) when input  
line voltage increases from 88 V to 380 V, with dual gain slopes.  
To optimize power supply efficiency, four different control  
modes are implemented. At maximum load, the modulator  
operates in full frequency PWM mode; as load decreases, the  
modulator automatically transitions, first to variable frequency  
PWM mode, then to low frequency PWM mode. At light load,  
the control operation switches from PWM control to multi-cycle-  
modulation control, and the modulator operates in multi-cycle-  
modulation mode. Although different modes operate differently  
to make transitions between modes smooth, the simple  
relationship between duty cycle and excess CONTROL pin  
current shown in Figure 9 is maintained through all three PWM  
modes. Please see the following sections for the details of the  
operation of each mode and the transitions between modes.  
Error Amplifier  
The shunt regulator can also perform the function of an error  
amplifier in primary side feedback applications. The shunt  
regulator voltage is accurately derived from a temperature-  
compensated bandgap reference. The CONTROL pin dynamic  
impedance ZC sets the gain of the error amplifier. The  
CONTROL pin clamps external circuit signals to the VC voltage  
level. The CONTROL pin current in excess of the supply  
current is separated by the shunt regulator and becomes the  
feedback current Ifb for the pulse width modulator.  
Full Frequency PWM mode: The PWM modulator enters full  
frequency PWM mode when the CONTROL pin current (IC)  
reaches IB. In this mode, the average switching frequency is  
kept constant at fOSC (66 kHz for P, G and M packages and  
TOP259-261 Y, pin selectable 132 kHz or 66 kHz for Y and E/L  
9
www.powerint.com  
Rev. F 01/09  
TOP252-262  
VUV  
VLINE  
0 V  
S14  
S14  
S15  
S13 S12  
S0  
S15 S14  
S13 S12  
S0  
S15  
S13 S12  
S0  
S15  
S15  
5.8 V  
4.8 V  
VC  
0 V  
VDRAIN  
0 V  
VOUT  
0 V  
1
2
3
2
4
Note: S0 through S15 are the output states of the auto-restart counter  
PI-4531-121206  
Figure 11. Typical Waveforms for (1) Power Up (2) Normal Operation (3) Auto-Restart (4) Power Down.  
On-Chip Current Limit with External Programmability  
The cycle-by-cycle peak drain current limit circuit uses the  
output MOSFET ON-resistance as a sense resistor. A current  
limit comparator compares the output MOSFET on-state drain  
to source voltage VDS(ON) with a threshold voltage. High drain  
current causes VDS(ON) to exceed the threshold voltage and turns  
the output MOSFET off until the start of the next clock cycle.  
The current limit comparator threshold voltage is temperature  
compensated to minimize the variation of the current limit due  
to temperature related changes in RDS(ON) of the output MOSFET.  
The default current limit of TOPSwitch-HX is preset internally.  
However, with a resistor connected between EXTERNAL  
CURRENT LIMIT (X) pin (Y, E/L and M packages) or MULTI-  
FUNCTION (M) pin (P and G package) and SOURCE pin (for  
TOP259-261 Y, the X pin is connected to the SIGNAL GROUND  
(G) pin), current limit can be programmed externally to a lower  
level between 30% and 100% of the default current limit. By  
setting current limit low, a larger TOPSwitch-HX than necessary  
for the power required can be used to take advantage of the  
lower RDS(ON) for higher efficiency/smaller heat sinking  
requirements. TOPSwitch-HX current limit reduction initial  
tolerance through the X pin (or M pin) has been improved  
significantly compare with previous TOPSwitch-GX. With a  
second resistor connected between the EXTERNAL CURRENT  
LIMIT (X) pin (Y, E/L and M packages) or MULTI-FUNCTION (M)  
pin (P and G package) and the rectified DC high voltage bus,  
the current limit is reduced with increasing line voltage, allowing  
a true power limiting operation against line variation to be  
implemented. When using an RCD clamp, this power limiting  
technique reduces maximum clamp voltage at high line. This  
allows for higher reflected voltage designs as well as reducing  
clamp dissipation.  
on. The leading edge blanking time has been set so that, if a  
power supply is designed properly, current spikes caused by  
primary-side capacitances and secondary-side rectifier reverse  
recovery time should not cause premature termination of the  
switching pulse.  
The current limit is lower for a short period after the leading  
edge blanking time. This is due to dynamic characteristics of  
the MOSFET. During startup and fault conditions the controller  
prevents excessive drain currents by reducing the switching  
frequency.  
Line Undervoltage Detection (UV)  
At power up, UV keeps TOPSwitch-HX off until the input line  
voltage reaches the undervoltage threshold. At power down,  
UV prevents auto-restart attempts after the output goes out of  
regulation. This eliminates power down glitches caused by slow  
discharge of the large input storage capacitor present in  
applications such as standby supplies. A single resistor  
connected from the VOLTAGE-MONITOR pin (Y, E/L and M  
packages) or MULTI-FUNCTION pin (P and G packages) to the  
rectified DC high voltage bus sets UV threshold during power  
up. Once the power supply is successfully turned on, the UV  
threshold is lowered to 44% of the initial UV threshold to allow  
extended input voltage operating range (UV low threshold). If  
the UV low threshold is reached during operation without the  
power supply losing regulation, the device will turn off and stay  
off until UV (high threshold) has been reached again. If the  
power supply loses regulation before reaching the UV low  
threshold, the device will enter auto-restart. At the end of each  
auto-restart cycle (S15), the UV comparator is enabled. If the  
UV high threshold is not exceeded, the MOSFET will be  
disabled during the next cycle (see Figure 11). The UV feature  
can be disabled independent of the OV feature.  
The leading edge blanking circuit inhibits the current limit  
comparator for a short time after the output MOSFET is turned  
10  
Rev. F 01/09  
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TOP252-262  
Line Overvoltage Shutdown (OV)  
clamp network, bias winding return or power traces from other  
converters. If the line sensing features are used, then the sense  
resistors must be placed within 10 mm of the V-pin to minimize  
the V-pin node area. The DC bus should then be routed to the  
line sense resistors. Note that external capacitance must not  
be connected to the V-pin as this may cause misoperaton of the  
V pin related functions.  
The same resistor used for UV also sets an overvoltage  
threshold, which, once exceeded, will force TOPSwitch-HX to  
stop switching instantaneously (after completion of the current  
switching cycle). If this condition lasts for at least 100 μs, the  
TOPSwitch-HX output will be forced into off state. Unlike with  
TOPSwitch-GX, however, when the line voltage is back to  
normal with a small amount of hysteresis provided on the OV  
threshold to prevent noise triggering, the state machine sets to  
S13 and forces TOPSwitch-HX to go through the entire auto-  
restart sequence before attempting to switch again. The ratio  
of OV and UV thresholds is preset at 4.5, as can be seen in  
Figure 12. When the MOSFET is off, the rectified DC high  
voltage surge capability is increased to the voltage rating of the  
MOSFET (700 V), due to the absence of the reflected voltage  
and leakage spikes on the drain. The OV feature can be  
disabled independent of the UV feature.  
Hysteretic or Latching Output Overvoltage Protection (OVP)  
The detection of the hysteretic or latching output overvoltage  
protection (OVP) is through the trigger of the line overvoltage  
threshold. The V-pin or M-pin voltage will drop by 0.5 V, and  
the controller measures the external attached impedance  
immediately after this voltage drops. If IV or IM exceeds IOV(LS)  
(336 μA typical) longer than 100 μs, TOPSwitch-HX will latch  
into a permanent off state for the latching OVP. It only can be  
reset if VV or VM goes below 1 V or VC goes below the power-  
up-reset threshold (VC(RESET)) and then back to normal.  
In order to reduce the no-load input power of TOPSwitch-HX  
designs, the V-pin (or M-pin for P Package) operates at very low  
currents. This requires careful layout considerations when  
designing the PCB to avoid noise coupling. Traces and  
components connected to the V-pin should not be adjacent to  
any traces carrying switching currents. These include the drain,  
If IV or IM does not exceed IOV(LS) or exceeds no longer than  
100 μs, TOPSwitch-HX will initiate the line overvoltage and the  
hysteretic OVP. Their behavior will be identical to the line  
overvoltage shutdown (OV) that has been described in detail in  
the previous section.  
Voltage Monitor and External Current Limit Pin Table*  
Figure Number  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
Three Terminal Operation  
Line Undervoltage  
Line Overvoltage  
Line Feed-Forward (DCMAX  
)
Output Overvoltage Protection  
Overload Power Limiting  
External Current Limit  
Remote ON/OFF  
Device Reset  
*This table is only a partial list of many VOLTAGE MONITOR and EXTERNAL CURRENT LIMIT Pin Configurations that are possible.  
Table 2. VOLTAGE MONITOR (V) Pin and EXTERNAL CURRENT LIMIT (X) Pin Configuration Options.  
Multi-Function Pin Table*  
Figure Number  
29  
30  
31  
32  
33  
34  
35  
36  
37  
38  
39  
40  
Three Terminal Operation  
Line Undervoltage  
Line Overvoltage  
Line Feed-Forward (DCMAX  
)
Output Overvoltage Protection  
Overload Power Limiting  
External Current Limit  
Remote ON/OFF  
Device Reset  
*This table is only a partial list of many MULTI-FUNCTIONAL Pin Configurations that are possible.  
Table 3. MULTI-FUNCTION (M) Pin Configuration Options.  
11  
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Rev. F 01/09  
TOP252-262  
M Pin  
X Pin  
V Pin  
IREM(N)  
IUV  
IOV  
IOV(LS)  
(Enabled)  
Output  
MOSFET  
Switching  
(Non-Latching) (Latching)  
(Disabled)  
Disabled when supply  
output goes out of  
regulation  
I
I
LIMIT (Default)  
Current  
Limit  
I
DCMAX (78%)  
Maximum  
Duty Cycle  
I
VBG  
Pin Voltage  
I
-250  
-200  
-150  
-100  
-50  
0
25  
50  
75  
100  
125  
336  
X and V Pins (Y, E, L and M Packages) and M Pin (P and G Packages) Current (μA)  
Note: This figure provides idealized functional characteristics with typical performance values. Please refer to the parametric  
table and typical performance characteristics sections of the data sheet for measured data. For a detailed description of  
each functional pin operation refer to the Functional Description section of the data sheet.  
PI-4646-071708  
Figure 12. MULTI-FUNCTION (P and G package). VOLTAGE MONITOR and EXTERNAL CURRENT LIMIT (Y, E/L and M package) Pin Characteristics.  
The circuit examples shown in Figures 41, 42 and 43 show a  
simple method for implementing the primary sensed over-  
voltage protection.  
The primary sensed OVP protection circuit shown in Figures 41,  
42 and 43 is triggered by a significant rise in output voltage (and  
therefore bias winding voltage). If the power supply is operating  
under heavy load or low input line conditions when an open  
loop occurs, the output voltage may not rise significantly.  
Under these conditions, a latching shutdown will not occur until  
load or line conditions change. Nevertheless, the operation  
provides the desired protection by preventing significant rise in  
the output voltage when the line or load conditions do change.  
Primary side OVP protection with the TOPSwitch-HX in a typical  
application will prevent a nominal 12 V output from rising above  
approximately 20 V under open loop conditions. If greater  
accuracy is required, a secondary sensed OVP circuit is  
recommended.  
During a fault condition resulting from loss of feedback, output  
voltage will rapidly rise above the nominal voltage. The increase  
in output voltage will also result in an increase in the voltage at  
the output of the bias winding. A voltage at the output of the  
bias winding that exceeds of the sum of the voltage rating of the  
Zener diode connected from the bias winding output to the  
V-pin (or M-pin) and V-pin (or M-pin) voltage, will cause a  
current in excess of IV or IM to be injected into the V-pin  
(or M-pin), which will trigger the OVP feature.  
12  
Rev. F 01/09  
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TOP252-262  
Line Feed-Forward with DCMAX Reduction  
Soft-Start  
The same resistor used for UV and OV also implements line voltage  
feed-forward, which minimizes output line ripple and reduces  
power supply output sensitivity to line transients. Note that for the  
same CONTROL pin current, higher line voltage results in smaller  
operating duty cycle. As an added feature, the maximum duty  
cycle DCMAX is also reduced from 78% (typical) at a voltage slightly  
lower than the UV threshold to 36% (typical) at the OV threshold.  
DCMAX of 36% at high line was chosen to ensure that the power  
capability of the TOPSwitch-HX is not restricted by this feature  
under normal operation. TOPSwitch-HX provides a better fit to the  
ideal feed-forward by using two reduction slopes: -1% per μA for all  
bus voltage less than 195 V (typical for 4 MΩ line impedance) and  
-0.25% per μA for all bus voltage more than 195 V. This dual  
slope line feed-forward improves the line ripple rejection  
significantly compared with the TOPSwitch-GX.  
The 17 ms soft-start sweeps the peak drain current and  
switching frequency linearly from minimum to maximum value  
by operating through the low frequency PWM mode and the  
variable frequency mode before entering the full frequency  
mode. In addition to start-up, soft-start is also activated at  
each restart attempt during auto-restart and when restarting  
after being in hysteretic regulation of CONTROL pin voltage (VC),  
due to remote OFF or thermal shutdown conditions. This  
effectively minimizes current and voltage stresses on the output  
MOSFET, the clamp circuit and the output rectifier during start-  
up. This feature also helps minimize output overshoot and  
prevents saturation of the transformer during start-up.  
Shutdown/Auto-Restart  
To minimize TOPSwitch-HX power dissipation under fault  
conditions, the shutdown/auto-restart circuit turns the power  
supply on and off at an auto-restart duty cycle of typically 2% if  
an out of regulation condition persists. Loss of regulation  
interrupts the external current into the CONTROL pin. VC  
regulation changes from shunt mode to the hysteretic auto-  
restart mode as described in CONTROL pin operation section.  
When the fault condition is removed, the power supply output  
becomes regulated, VC regulation returns to shunt mode, and  
normal operation of the power supply resumes.  
Remote ON/OFF  
TOPSwitch-HX can be turned on or off by controlling the  
current into the VOLTAGE-MONITOR pin or out from the  
EXTERNAL CURRENT LIMIT pin (Y, E/L and M packages) and  
into or out from the MULTI-FUNCTION pin (P and G package,  
see Figure 12). In addition, the VOLTAGE-MONITOR pin has a  
1 V threshold comparator connected at its input. This voltage  
threshold can also be used to perform remote ON/OFF control.  
Hysteretic Over-Temperature Protection  
Temperature protection is provided by a precision analog circuit  
that turns the output MOSFET off when the junction  
When a signal is received at the VOLTAGE-MONITOR pin or the  
EXTERNAL CURRENT LIMIT pin (Y, E/L and M packages) or the  
MULTI-FUNCTION pin (P and G package) to disable the output  
through any of the pin functions such as OV, UV and remote  
ON/OFF, TOPSwitch-HX always completes its current switching  
cycle before the output is forced off.  
temperature exceeds the thermal shutdown temperature  
(142 °C typical). When the junction temperature cools to below  
the lower hysteretic temperature point, normal operation  
resumes, thus providing automatic recovery. A large hysteresis  
of 75 °C (typical) is provided to prevent overheating of the PC  
board due to a continuous fault condition. VC is regulated in  
hysteretic mode, and a 4.8 V to 5.8 V (typical) triangular waveform  
is present on the CONTROL pin while in thermal shutdown.  
As seen above, the remote ON/OFF feature can also be used as  
a standby or power switch to turn off the TOPSwitch-HX and  
keep it in a very low power consumption state for indefinitely  
long periods. If the TOPSwitch-HX is held in remote off state for  
long enough time to allow the CONTROL pin to discharge to the  
internal supply undervoltage threshold of 4.8 V (approximately  
32 ms for a 47 μF CONTROL pin capacitance), the CONTROL  
pin goes into the hysteretic mode of regulation. In this mode,  
the CONTROL pin goes through alternate charge and discharge  
cycles between 4.8 V and 5.8 V (see CONTROL pin operation  
section above) and runs entirely off the high voltage DC input,  
but with very low power consumption (160 mW typical at  
230 VAC with M or X pins open). When the TOPSwitch-HX is  
remotely turned on after entering this mode, it will initiate a  
normal start-up sequence with soft-start the next time the  
CONTROL pin reaches 5.8 V. In the worst case, the delay from  
remote on to start-up can be equal to the full discharge/charge  
cycle time of the CONTROL pin, which is approximately 125 ms  
for a 47 μF CONTROL pin capacitor. This reduced  
Bandgap Reference  
All critical TOPSwitch-HX internal voltages are derived from a  
temperature-compensated bandgap reference. This voltage  
reference is used to generate all other internal current  
references, which are trimmed to accurately set the switching  
frequency, MOSFET gate drive current, current limit, and the  
line OV/UV/OVP thresholds. TOPSwitch-HX has improved  
circuitry to maintain all of the above critical parameters within  
very tight absolute and temperature tolerances.  
High-Voltage Bias Current Source  
This high-voltage current source biases TOPSwitch-HX from the  
DRAIN pin and charges the CONTROL pin external capacitance  
during start-up or hysteretic operation. Hysteretic operation  
occurs during auto-restart, remote OFF and over-temperature  
shutdown. In this mode of operation, the current source is  
switched on and off, with an effective duty cycle of approxi-  
mately 35%. This duty cycle is determined by the ratio of  
CONTROL pin charge (IC) and discharge currents (ICD1 and ICD2).  
This current source is turned off during normal operation when  
the output MOSFET is switching. The effect of the current  
source switching will be seen on the DRAIN voltage waveform  
as small disturbances and is normal.  
consumption remote off mode can eliminate expensive and  
unreliable in-line mechanical switches. It also allows for  
microprocessor controlled turn-on and turn-off sequences that  
may be required in certain applications such as inkjet and laser  
printers.  
13  
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Rev. F 01/09  
TOP252-262  
Y, E/L and M Package  
CONTROL (C)  
TOPSwitch-HX  
200 MA  
(Negative Current Sense - ON/OFF,  
Current Limit Adjustment)  
VBG + VT  
EXTERNAL CURRENT LIMIT (X)  
VOLTAGE MONITOR (V)  
(Voltage Sense)  
1 V  
VREF  
(Positive Current Sense - Undervoltage,  
Overvoltage, ON/OFF, Maximum Duty  
Cycle Reduction, Output Over-  
voltage Protection)  
400 MA  
PI-4714-071408  
Figure 13a. VOLTAGE MONITOR (V) and EXTERNAL CURRENT LIMIT (X) Pin Input Simplified Schematic.  
P and G Package  
CONTROL (C)  
TOPSwitch-HX  
200 MA  
(Negative Current Sense - ON/OFF,  
Current Limit Adjustment)  
VBG + VT  
MULTI-FUNCTION (M)  
VREF  
(Positive Current Sense - Undervoltage,  
Overvoltage, Maximum Duty Cycle Reduction,  
Output Overvoltage Protection)  
400 MA  
PI-4715-071408  
Figure 13b. MULTI-FUNCTION (M) Pin Input Simplified Schematic.  
14  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
Typical Uses of FREQUENCY (F) Pin  
+
+
DC  
Input  
DC  
Input  
Voltage  
D
S
D
CONTROL  
CONTROL  
Voltage  
C
C
S
F
F
-
-
PI-2655-071700  
PI-2654-071700  
Figure 14. Full Frequency Operation (132 kHz).  
Figure 15. Half Frequency Operation (66 kHz).  
15  
www.powerint.com  
Rev. F 01/09  
TOP252-262  
Typical Uses of VOLTAGE MONITOR (V) and EXTERNAL CURRENT LIMIT (X) Pins  
TOP252-258M  
TOP254-258Y  
+
+
TOP259-261Y  
D
S
C
S
X
S
V
S
S
V X C S  
F
D
DC  
Input  
Voltage  
DC  
Input  
Voltage  
V X C S G  
D
D
S
C
D
S
V
D
S
V
C
S
D
CONTROL  
CONTROL  
C
C
C S  
D
X
G
X
F
-
-
PI-4984-020708  
PI-4716-020508  
Figure 16a. Three Terminal Operation (VOLTAGE MONITOR and EXTERNAL  
CURRENT LIMIT Features Disabled. FREQUENCY Pin Tied to  
SOURCE or CONTROL Pin) for TOP254-258 Y Packages.  
Figure 16b. Three Terminal Operation (VOLTAGE MONITOR and EXTERNAL  
CURRENT LIMIT Features Disabled for TOP259-261 Y Packages.  
+
+
VUV = IUV × RLS + VV (IV = IUV  
VOV = IOV × RLS + VV (IV = IOV  
)
)
eSIP L Package eSIP E Package  
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
V X C  
F
S
D
V X C  
F
S
D
RLS 4 M7  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
DCMAX@100 VDC = 76%  
DCMAX@375 VDC = 41%  
C
S
D
C
S
D
D
S
V
D
S
V
CONTROL  
CONTROL  
C
C
X
F
-
-
PI-4717-120307  
PI-4956-071708  
Figure 17. Line-Sensing for Undervoltage, Overvoltage and Line Feed-Forward.  
Figure 16c. Three Terminal Operation (VOLTAGE MONITOR and EXTERNAL  
CURRENT LIMIT Features Disabled. FREQUENCY Pin Tied to  
SOURCE or CONTROL Pin) for TOP252-262 L and E Packages.  
VUV = IUV × RLS + VV (IV = IUV  
VOV = IOV × RLS + VV (IV = IOV  
)
)
+
+
VUV = IUV × RLS + VV (IV = IUV  
VOV = IOV × RLS + VV (IV = IOV  
)
)
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
Sense Output Voltage  
RLS  
RLS  
4 M7  
4 M7  
ROVP  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
VROVP  
Sense Output Voltage  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
D
S
V
D
S
V
10 k7  
CONTROL  
CONTROL  
Reset  
C
C
QR  
ROVP >3k7  
-
-
PI-4756-121007  
PI-4719-120307  
Figure 18. Line-Sensing for Undervoltage, Overvoltage, Line Feed-Forward and  
Latched Output Overvoltage Protection.  
Figure 19. Line-Sensing for Undervoltage, Overvoltage, Line Feed-Forward and  
Hysteretic Output Overvoltage Protection.  
16  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
Typical Uses of VOLTAGE MONITOR (V) and EXTERNAL CURRENT LIMIT (X) Pins (cont.)  
+
+
VUV = RLS × IUV + VV (IV = IUV  
)
VOV = IOV × RLS + VV (IV = IOV  
)
4 M7  
40 k7  
4 M7  
For Values Shown  
VUV = 103.8 VDC  
For Values Shown  
VOV = 457.2 VDC  
RLS  
R
LS  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
55 k7  
1N4148  
D
V
D
S
V
CONTROL  
CONTROL  
C
C
6.2 V  
S
-
-
PI-4720-120307  
PI-4721-120307  
Figure 20. Line Sensing for Undervoltage Only (Overvoltage Disabled).  
Figure 21. Line-Sensing for Overvoltage Only (Undervoltage Disabled). Maximum  
Duty Cycle Reduced at Low Line and Further Reduction with  
Increasing Line Voltage.  
+
+
I
LIMIT = 100% @ 100 VDC  
For RIL = 12 k7  
LIMIT = 61%  
53% @ 300 VDC  
ILIMIT  
=
I
RLS  
2.5 M7  
TOP259-261YN would  
use the G pin as the  
return for RIL.  
For RIL = 19 k7  
ILIMIT = 37%  
See Figure 55b for other  
resistor values (RIL).  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
D
S
D
S
CONTROL  
X
CONTROL  
C
C
TOP259-261YN would  
use the G pin as the  
return for RIL.  
X
RIL  
RIL  
6 k7  
-
-
PI-4723-011008  
PI-4722-021308  
Figure 22. External Set Current Limit.  
Figure 23. Current Limit Reduction with Line Voltage.  
+
+
Q
R can be an optocoupler  
QR can be an optocoupler  
output or can be replaced by  
a manual switch.  
output or can be replaced  
by a manual switch.  
TOP259-261YN would  
use the G pin as the  
return for QR.  
For RIL =12 k7  
ILIMIT = 61%  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
D
D
S
For RIL = 19 k7  
CONTROL  
CONTROL  
ILIMIT = 37%  
C
C
TOP259-261YN would  
use the G pin as the  
return for QR.  
S
X
X
RIL  
ON/OFF  
QR  
QR  
ON/OFF  
47 K7  
-
16 k7  
-
PI-2625-011008  
PI-4724-011008  
Figure 25. Active-on Remote ON/OFF with Externally Set Current Limit.  
Figure 24. Active-on (Fail Safe) Remote ON/OFF.  
17  
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Rev. F 01/09  
TOP252-262  
Typical Uses of VOLTAGE MONITOR (V) and EXTERNAL CURRENT LIMIT (X) Pins (cont.)  
VUV = IUV × RLS + VV (IV = IUV  
)
VUV = IUV x RLS + VV (IV = IUV  
)
+
+
VOV = IOV × RLS + VV (IV = IoV  
)
VOV = IOV x RLS + VV (IV = IoV  
)
For RLS = 4 M7  
DCMAX@100 VDC = 76%  
DCMAX@375 VDC = 41%  
4 M7  
RLS  
4 M7  
RLS  
VUV = 102.8 VDC  
VOV = 451 VDC  
QR can be an optocoupler  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
output or can be replaced  
by a manual switch.  
D
S
V
D
S
V
CONTROL  
CONTROL  
C
C
For RIL =12 k7  
For RIL = 12 k7  
ILIMIT = 61%  
I
LIMIT = 61%  
TOP259-261YN would  
use the G pin as the  
return for QR.  
TOP259-261YN would  
use the G pin as the  
return for RIL.  
X
X
See Figure 55b for  
other resistor values  
(RIL) to select different  
ILIMIT values.  
RIL  
QR  
RIL  
12 k7  
ON/OFF  
16 k7  
-
-
PI-4725-011008  
Figure 26. Active-on Remote ON/OFF with Line-Sense and External  
Current Limit.  
Figure 27. Line Sensing and Externally Set Current Limit.  
+
VUV = IUV × RLS + VV (IV = IUV  
)
VOV = IOV × RLS + VV (IV = IOV  
)
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
RLS  
4 M7  
DC  
Input  
Sense Output Voltage  
Voltage  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
D
S
V
10 k7  
CONTROL  
Reset  
C
QR  
-
PI-4756-121007  
Figure 28. Line-Sensing for Undervoltage, Overvoltage, Line Feed-Forward and  
Latched Output Overvoltage Protection with Device Reset.  
Typical Uses of MULTI-FUNCTION (M) Pin  
+
+
VUV = IUV × RLS + VM (IM = IUV  
)
VOV = IOV × RLS + VM (IM = IOV  
)
D
S
C
S
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
M
S
RLS  
4 M7  
S
DC  
Input  
Voltage  
DC  
Input  
Voltage  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
D
S
M
D
S
M
D
S
C
CONTROL  
CONTROL  
C
C
-
-
PI-4728-120307  
PI-4727-061207  
Figure 29. Three Terminal Operation (MULTI-FUNCTION Features Disabled).  
Figure 30. Line Sensing for Undervoltage, Overvoltage and Line Feed-Forward.  
18  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
Typical Uses of MULTI-FUNCTION (M) Pin (cont.)  
VUV = IUV × RLS + VM (IM = IUV  
VOV = IOV × RLS + VM (IM = IOV  
)
)
+
+
VUV = IUV × RLS + VM (IM = IUV  
VOV = IOV × RLS + VM (IM = IOV  
)
)
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
For RLS = 4 M7  
Sense Output Voltage  
VUV = 102.8 VDC  
RLS  
RLS  
4 M7  
4 M7  
VOV = 451 VDC  
ROVP  
DC  
Input  
DC  
Input  
VROVP  
Sense Output Voltage  
Voltage  
Voltage  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
D
S
M
D
S
M
CONTROL  
CONTROL  
C
C
ROVP >3k7  
-
-
PI-4729-120307  
PI-4730-120307  
Figure 32. Line Sensing for Undervoltage, Overvoltage, Line Feed-Forward and  
Hysteretic Output Overvoltage Protection.  
Figure 31. Line Sensing for Undervoltage, Overvoltage, Line Feed-Forward and  
Latched Output Overvoltage Protection.  
+
+
VUV = RLS × IUV + VM (IM = IUV  
)
VOV = IOV × RLS + VM (IM = IOV  
)
4 M7  
4 M7  
For Values Shown  
For Values Shown  
VUV = 103.8 VDC  
VOV = 457.2 VDC  
RLS  
RLS  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
40 k7  
55 k7  
1N4148  
D
S
M
D
S
M
CONTROL  
CONTROL  
C
C
6.2 V  
-
-
PI-4732-120307  
PI-4731-120307  
Figure 34. Line Sensing for Overvoltage Only (Undervoltage Disabled). Maximum  
Duty Cycle Reduced at Low Line and Further Reduction with  
Increasing Line Voltage.  
Figure 33. Line Sensing for Undervoltage Only (Overvoltage Disabled).  
+
+
For RIL = 12 k7  
ILIMIT = 61%  
ILIMIT = 100% @ 100 VDC  
53% @ 300 VDC  
ILIMIT  
=
RLS  
2.5 M7  
For RIL = 19 k7  
ILIMIT = 37%  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
See Figures 55b for other  
resistor values (RIL) to  
select different ILIMIT values.  
D
S
M
D
S
M
CONTROL  
CONTROL  
RIL  
6 k7  
C
C
RIL  
-
-
PI-4734-092107  
PI-4733-021308  
Figure 36. Current Limit Reduction with Line Voltage (Not Normally Required –  
See M Pin Operation Description).  
Figure 35. Externally Set Current Limit (Not Normally Required – See M Pin  
Operation Description).  
19  
www.powerint.com  
Rev. F 01/09  
TOP252-262  
Typical Uses of MULTI-FUNCTION (M) Pin (cont.)  
+
+
Q
R can be an optocoupler  
QR can be an optocoupler  
output or can be replaced  
by a manual switch.  
output or can be replaced  
by a manual switch.  
For RIL = 12 k7  
ILIMIT = 61%  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
For RIL = 19 k7  
ILIMIT = 37%  
D
S
M
D
S
M
RIL  
CONTROL  
CONTROL  
QR  
C
C
ON/OFF  
QR  
ON/OFF  
47 k7  
16 k7  
-
-
PI-2519-040501  
PI-4735-092107  
Figure 38. Active-on Remote ON/OFF with Externally Set Current Limit  
(see M Pin Operation Description).  
Figure 37. Active-on (Fail Safe) Remote ON/OFF.  
+
+
Q
R can be an optocoupler  
VUV = IUV × RLS + VM (IM = IUV  
VOV = IOV × RLS + VM (IM = IOV  
)
)
output or can be replaced  
by a manual switch.  
For RLS = 4 M7  
VUV = 102.8 VDC  
VOV = 451 VDC  
RLS  
4 M7  
ON/OFF  
QR  
DC  
Input  
Voltage  
DC  
Input  
Voltage  
Sense Output Voltage  
7 k7  
DCMAX @ 100 VDC = 76%  
DCMAX @ 375 VDC = 41%  
RMC  
24 k7  
RMC = 2RIL  
D
S
M
D
M
10 k7  
CONTROL  
CONTROL  
Reset  
C
RIL  
C
QR  
12 k7  
S
-
-
PI-4757-120307  
PI-4736-060607  
Figure 40. Line-Sensing for Undervoltage, Overvoltage, Line Feed-Forward and  
Latched Output Overvoltage Protection with Device Reset.  
Figure 39. Active-off Remote ON/OFF with Externally Set Current Limit  
(see M Pin Operation Description).  
20  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
winding. Zener VR2 will break down and current will flow into  
the “M” pin of the TOPSwitch initiating a hysteretic overvoltage  
protection with automatic restart attempts. Resistor R5 will limit  
the current into the M pin to < 336 μA, thus setting hysteretic  
OVP. If latching OVP is desired, the value of R5 can be reduced  
to 20 Ω.  
Application Examples  
A High Efficiency, 35 W, Dual Output - Universal Input  
Power Supply  
The circuit in Figure 41 takes advantage of several of the  
TOPSwitch-HX features to reduce system cost and power  
supply size and to improve efficiency. This design delivers  
35 W total continuous output power from a 90 VAC to 265 VAC  
input at an ambient of 50 ºC in an open frame configuration. A  
nominal efficiency of 84% at full load is achieved using  
TOP258P. With a DIP-8 package, this design provides 35 W  
continuous output power using only the copper area on the  
circuit board underneath the part as a heat sink. The different  
operating modes of the TOPSwitch-HX provide significant  
improvement in the no-load, standby, and light load  
performance of the power supply as compared to the previous  
generations of the TOPSwitch.  
The output voltage is controlled using the amplifier TL431.  
Diode D9, capacitor C20 and resistor R16 form the soft finish  
circuit. At startup, capacitor C20 is discharged. As the output  
voltage starts rising, current flows through the optocoupler diode  
inside U2A, resistor R13 and diode D9 to charge capacitor C20.  
This provides feedback to the circuit on the primary side. The  
current in the optocoupler diode U2A gradually decreases as the  
capacitor C20 becomes charged and the control amplifier IC U3  
becomes operational. This ensures that the output voltage  
increases gradually and settles to the final value without any  
overshoot. Resistor R16 ensures that the capacitor C20 is  
maintained charged at all times after startup, which effectively  
isolates C20 from the feedback circuit after startup. Capacitor  
C20 discharges through R16 when the supply shuts down.  
Resistors R3 and R4 provide line sensing, setting line UV at  
100 VDC and line OV at 450 VDC.  
Diode D5, together with resistors R6, R7, capacitor C6 and TVS  
VR1, forms a clamp network that limits the drain voltage of the  
TOPSwitch after the integrated MOSFET turns off. TVS VR1  
provides a defined maximum clamp voltage and typically only  
conducts during fault conditions such as overload. This allows  
the RCD clamp (R6, R7, C6 and D5) to be sized for normal  
operation, thereby maximizing efficiency at light load. Should  
the feedback circuit fail, the output of the power supply may  
exceed regulation limits. This increased voltage at output will  
also result in an increased voltage at the output of the bias  
Resistors R20, R21 and R18 form a voltage divider network.  
The output of this divider network is primarily dependent on the  
divider circuit formed using R20 and R21 and will vary to some  
extent for changes in voltage at the 15 V output due to the  
connection of resistor R18 to the output of the divider network.  
Resistor R19 and Zener VR3 improve cross regulation in case  
only the 5 V output is loaded, which results in the 15 V output  
operating at the higher end of the specification.  
C7  
C12  
470 pF  
100 V  
R11  
33 7  
C6  
2.2 nF  
3.9 nF  
250 VAC  
1 kV  
C13  
680 MF  
25 V  
C14  
680 MF  
25 V  
C15  
220 MF  
25 V  
D7  
SB560  
L2  
T1  
EER28  
R6  
3.3 MH  
+12 V,  
2 A  
22 k7  
2
7
2 W  
VR1  
C16  
470 pF  
100 V  
C18  
220 MF  
10 V  
D1  
1N4937  
D2  
1N4007  
R12  
33 7  
L3  
3.3 MH  
P6KE200A  
RTN  
3
11  
+5 V,  
2.2 A  
D8  
R7  
SB530  
20 7  
1/2 W  
4
9
6
RTN  
C17  
C10  
2200 MF  
10 MF  
10 V  
C11  
2.2 nF  
250 VAC  
D5  
FR106  
R10  
4.7 7  
50 V  
R3  
2.0 M7  
D3  
1N4937  
D4  
1N4007  
D6  
R19  
10 7  
FR106  
5
L1  
6.8 mH  
R4  
2.0 M7  
VR3  
R14  
BZX55B8V2  
8.2 V  
22 7  
R13  
330 7  
C4  
100 MF  
400 V  
2%  
C19  
1.0 MF  
50 V  
R1  
R2  
VR2  
1N5250B  
20 V  
1 M7 1 M7  
R5  
5.1 k7  
C3  
220 nF  
275 VAC  
R15  
1 k7  
F1  
3.15 A  
U2B  
PS2501-  
1-H-A  
U2A  
TOPSwitch-HX  
PS2501-  
1-H-A  
tO  
R18  
196 k7  
1%  
R20  
RT1  
10 7  
D
M
U1  
L
E
N
TOP258PN  
C
12.4 k7  
CONTROL  
1%  
R17  
10 k7  
R16  
10 k7  
D9  
1N4148  
R8  
S
6.8 7  
C8  
100 nF  
50 V  
90 - 265  
VAC  
C21  
220 nF  
50 V  
C9  
47 MF  
16 V  
C20  
10 MF  
50 V  
U3  
TL431  
2%  
R21  
10 k7  
1%  
PI-4747-020508  
Figure 41. 35 W Dual Output Power Supply using TOP258PN.  
21  
www.powerint.com  
Rev. F 01/09  
TOP252-262  
dissipated by VR1 and VR3, the leakage energy instead being  
dissipated by R1 and R2. However, VR1 and VR3 are essential  
to limit the peak drain voltage during start-up and/or overload  
conditions to below the 700 V rating of the TOPSwitch-HX  
MOSFET. The schematic shows an additional turn-off snubber  
circuit consisting of R20, R21, R22, D5 and C18. This reduces  
turn-off losses in the TOPSwitch-HX.  
A High Efficiency, 150 W, 250 – 380 VDC Input  
Power Supply  
The circuit shown in Figure 42 delivers 150 W (19 V @ 7.7 A) at  
84% efficiency using a TOP258Y from a 250 VDC to 380 VDC  
input. A DC input is shown, as typically at this power level a  
power factor correction stage would precede this supply,  
providing the DC input. Capacitor C1 provides local decoupling,  
necessary when the supply is remote from the main PFC output  
capacitor.  
The secondary is rectified and smoothed by D2, D3 and C5,  
C6, C7 and C8. Two windings are used and rectified with  
separate diodes D2 and D3 to limit diode dissipation. Four  
capacitors are used to ensure their maximum ripple current  
specification is not exceeded. Inductor L1 and capacitors C15  
and C16 provide switching noise filtering.  
The flyback topology is still usable at this power level due to the  
high output voltage, keeping the secondary peak currents low  
enough so that the output diode and capacitors are reasonably  
sized. In this example, the TOP258YN is at the upper limit of its  
power capability.  
Output voltage is controlled using a TL431 reference IC and  
R15, R16 and R17 to form a potential divider to sense the  
output voltage. Resistor R12 and R24 together limit the  
optocoupler LED current and set overall control loop DC gain.  
Control loop compensation is achieved using components C12,  
C13, C20 and R13. Diode D6, resistor R23 and capacitor C19  
form a soft finish network. This feeds current into the control  
pin prior to output regulation, preventing output voltage  
overshoot and ensuring startup under low line, full load  
conditions.  
Resistors R3, R6 and R7 provide output power limiting,  
maintaining relatively constant overload power with input voltage.  
Line sensing is implemented by connecting a 4 MΩ resistor from  
the V pin to the DC rail. Resistors R4 and R5 together form the  
4 MΩ line sense resistor. If the DC input rail rises above  
450 VDC, then TOPSwitch-HX will stop switching until the  
voltage returns to normal, preventing device damage.  
Due to the high primary current, a low leakage inductance  
transformer is essential. Therefore, a sandwich winding with a  
copper foil secondary was used. Even with this technique, the  
leakage inductance energy is beyond the power capability of a  
simple Zener clamp. Therefore, R1, R2 and C3 are added in  
parallel to VR1 and VR3, two series TVS diodes being used to  
reduce dissipation. During normal operation, very little power is  
Sufficient heat sinking is required to keep the TOPSwitch-HX  
device below 110 °C when operating under full load, low line  
and maximum ambient temperature. Airflow may also be  
required if a large heat sink area is not acceptable.  
2.2 nF  
C14  
47 pF  
1 kV  
R14  
250 VAC  
22  
7
C4  
R2  
68 k7  
2 W  
R1  
68 k7  
2 W  
0.5 W  
250 - 380  
C5-C8  
820 MF  
25 V  
C15-C16  
820 MF  
25 V  
VDC  
+19 V,  
7.7 A  
L1  
1
4
13,14  
F1  
RT1  
5 7  
C3  
4.7 nF  
1 kV  
tO  
3.3 MH  
4 A  
R6  
4.7 M  
R4  
D2  
7
2.0 M7  
MBR20100CT  
11  
12  
D1  
BYV26C  
D3  
RTN  
R7  
4.7 M  
R5  
2.0 -7  
MBR20100CT  
7
VR1, VR3  
P6KE100A  
9,10  
7
D4  
1N4148  
5
C1  
22 MF  
400 V  
R18  
C17  
22 7  
47 pF  
R20  
1.5 k7  
2 W  
0.5 W  
1 kV  
R12  
240 7  
0.125 W  
C20  
T1  
EI35  
R8  
4.7  
1.0 MF  
7
50 V  
C9  
10 MF  
D5  
1N4937  
R24  
VR2  
1N525  
36 V  
50 V  
30 7  
R21  
1.5 k7  
2 W  
0.125 W  
8B  
R16  
31.6 k7  
1%  
R19  
4.7 7  
R23  
15 k7  
U2  
PC817A  
0.125 W  
R11  
TOPSwitch-HX  
U1  
TOP258YN  
R17  
562 7  
1%  
C12  
4.7 nF  
50 V  
1 k7  
0.125 W  
D
V
R22  
1.5 k7  
2 W  
CONTROL  
U2  
PC817B  
C
C13  
100 nF  
50 V  
R13  
56 k7  
R10  
0.125 W  
S
X
F
D6  
1N4148  
6.8 7  
C11  
100 nF  
50 V  
C19  
10 MF  
R3  
8.06 k7  
1%  
C18  
120 pF  
1 kV  
C10  
47 MF  
10 V  
50 V  
U3  
TL431  
2%  
R15  
4.75 k7  
1%  
PI-4795-092007  
Figure 42. 150 W, 19 V Power Supply using TOP258YN.  
22  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
A High Efficiency, 20 W continuous – 80 W Peak, Universal  
Input Power Supply  
TOPSwitch-HX and R20, C9, R22 and VR5. Should the bias  
winding output voltage across C13 rise due to output overload  
or an open loop fault (opto coupler failure), then VR5 conducts  
triggering the latching shutdown. To prevent false triggering  
due to short duration overload, a delay is provided by R20, R22  
and C9.  
The circuit shown in Figure 43 takes advantage of several of  
TOPSwitch-HX features to reduce system cost and power  
supply size and to improve power supply efficiency while  
delivering significant peak power for a short duration. This  
design delivers continuous 20 W and peak 80 W at 32 V from  
an 90 VAC to 264 VAC input. A nominal efficiency of 82% at full  
load is achieved using TOP258MN. The M-package part has an  
optimized current limit to enable design of power supplies  
capable of delivering high power for a short duration.  
To reset the supply following a latching shutdown, the V pin  
must fall below the reset threshold. To prevent the long reset  
delay associated with the input capacitor discharging, a fast AC  
reset circuit is used. The AC input is rectified and filtered by  
D13 and C30. While the AC supply is present, Q3 is on and Q1  
is off, allowing normal device operation. However when AC is  
removed, Q1 pulls down the V pin and resets the latch. The supply  
will then return to normal operation when AC is again applied.  
Resistor R12 sets the current limit of the part. Resistors R11  
and R14 provide line feed forward information that reduces the  
current limit with increasing DC bus voltage, thereby maintaining  
a constant overload power level with increasing line voltage.  
Resistors R1 and R2 implement the line undervoltage and over-  
voltage function and also provide feed forward compensation for  
reducing line frequency ripple at the output. The overvoltage  
feature inhibits TOPSwitch-HX switching during a line surge  
extending the high voltage withstand to 700 V without device  
damage.  
Transistor Q2 provides an additional lower UV threshold to the  
level programmed via R1, R2 and the V pin. At low input AC  
voltage, Q2 turns off, allowing the X pin to float and thereby  
disabling switching.  
A simple feedback circuit automatically regulates the output  
voltage. Zener VR3 sets the output voltage together with the  
voltage drop across series resistor R8, which sets the DC gain  
of the circuit. Resistors R10 and C28 provide a phase boost to  
improve loop bandwidth.  
The snubber circuit comprising of VR7, R17, R25, C5 and D2  
limits the maximum drain voltage and dissipates energy stored in  
the leakage inductance of transformer T1. This clamp  
configuration maximizes energy efficiency by preventing C5 from  
discharging below the value of VR7 during the lower frequency  
operating modes of TOPSwitch-HX. Resistor R25 damps high  
frequency ringing for reduced EMI.  
Diodes D6 and D7 are low-loss Schottky rectifiers, and  
capacitor C20 is the output filter capacitor. Inductor L3 is a  
common mode choke to limit radiated EMI when long output  
cables are used and the output return is connected to safety  
earth ground. Example applications where this occurs include  
PC peripherals, such as inkjet printers.  
A combined output overvoltage and over power protection  
circuit is provided via the latching shutdown feature of  
C8  
1 nF  
250 VAC  
R19 C26  
68 100 pF  
0.5 W 1 kV  
7
C31  
C20  
330  
50 V  
32 V  
625 mA, 2.5 APK  
M
F
22  
M
F
L2  
50 V  
L3  
1
2
3
10  
3.3  
M
H
D6-D7  
D8  
1N4007  
D9  
1N4007  
VR7  
BZY97C150  
150 V  
RTN  
STPS3150  
9
5
R25  
C3  
120  
400 V  
47 MH  
100  
7
MF  
C29  
220 nF  
50 V  
o
C13  
t
R11  
10  
M
F
R1  
2 M  
NC  
C10  
R17  
RT1  
10  
3.6 M  
7
50 V  
D11  
D10  
7
C5  
10 nF  
1 kV  
1 nF  
1 k  
7
4
1N4007  
1N4007  
7
250 VAC  
0.5 W  
D5  
T1  
EF25  
LL4148  
R10  
56  
7
R8  
1.5 k  
L1  
7
D2  
FR107  
5.3 mH  
R2  
2 M  
R14  
C28  
330 nF  
50 V  
7
3.6 M  
7
D13  
1N4007  
R24  
R23  
VR3  
1N5255B  
28 V  
1 M  
7
1 M  
7
U2A  
PC817D  
VR5  
1N5250B  
20 V  
R20  
130 k  
C9  
R3  
2 M  
7
R22  
1 MF  
7
V
D
S
100 V  
2 M  
7
C1  
F1  
3.15 A  
R21  
220 nF  
CONTROL  
R9  
275 VAC  
1 M  
7
2 k  
7
R4  
2 M  
0.125 W  
7
C
PI-4833-092007  
90 - 264  
VAC  
X
R15  
1 k  
7
R6  
6.8 7  
TOPSwitch-HX  
U4  
TOP258MN  
R12  
7.5 k  
1%  
C6  
100 nF  
50 V  
Q1  
2N3904  
7
C30  
100 nF  
Q2  
2N3904  
400 V  
Q3  
2N3904  
C7  
47  
16 V  
MF  
R26  
68 k  
R18  
39 k  
7
7
Figure 43. 20 W Continuous, 80 W Peak, Universal Input Power Supply using TOP258MN.  
23  
www.powerint.com  
Rev. F 01/09  
TOP252-262  
A High Efficiency, 65 W, Universal Input Power Supply  
The circuit shown in Figure 44 delivers 65 W (19 V @ 3.42 A) at  
88% efficiency using a TOP260EN operating over an input  
voltage range of 90 VAC to 265 VAC.  
The secondary output from the transformer is rectified by diode  
D2 and filtered by capacitors C13 and C14. Ferrite Bead L3 and  
capacitors C15 form a second stage filter and effectively reduce  
the switching noise to the output.  
Capacitors C1 and C6 and inductors L1 and L2 provide  
common mode and differential mode EMI filtering. Capacitor C2  
is the bulk filter capacitor that ensures low ripple DC input to the  
flyback converter stage. Capacitor C4 provides decoupling for  
switching currents reducing differential mode EMI.  
Output voltage is controlled using a LM431 reference IC.  
Resistor R19 and R20 form a potential divider to sense the  
output voltage. Resistor R16 limits the optocoupler LED current  
and sets the overall control loop DC gain. Control loop  
compensation is achieved using C18 and R21. The components  
connected to the control pin on the primary side C8, C9 and  
R15 set the low frequency pole and zero to further shape the  
control loop response. Capacitor C17 provides a soft finish  
during startup. Optocoupler U2 is used for isolation of the  
feedback signal.  
In this example, the TOP260EN is used at reduced current limit  
to improve efficiency.  
Resistors R5, R6 and R7 provide power limiting, maintaining  
relatively constant overload power with input voltage. Line  
sensing is implemented by connecting a 4 MΩ impedance from  
the V pin to the DC rail. Resistors R3 and R4 together form the  
4 MΩ line sense resistor. If the DC input rail rises above  
450 VDC, then TOPSwitch-HX will stop switching until the  
voltage returns to normal, preventing device damage.  
Diode D4 and capacitor C10 form the bias winding rectifier and  
filter. Should the feedback loop break due to a defective  
component, a rising bias winding voltage will cause the zener  
VR2 to break down and trigger the over voltage protection  
which will inhibit switching.  
This circuit features a high efficiency clamp network consisting  
of diode D1, zener VR1, capacitor C5 together with resistors R8  
and R9. The snubber clamp is used to dissipate the energy of  
the leakage reactance of the transformer. At light load levels,  
very little power is dissipated by VR1 improving efficiency as  
compared to a conventional RCD clamp network.  
An optional secondary side over voltage protection feature  
which offers higher precision (as compared to sensing via the  
bias winding) is implemented using VR3, R18 and U3. Excess  
voltage at the output will cause current to flow through the  
optocoupler U3 LED which in turn will inject current in the V-pin  
through resistor R13, thereby triggering the over voltage  
protection feature.  
C6  
C12  
1 nF  
100 V  
2.2 nF  
R16  
33 7  
250 VAC  
L3  
Ferrite  
Bead  
C5  
C13  
470 MF 470 MF  
25 V 25 V  
C14  
C15  
47 MF  
25 V  
VR1  
2.2 nF  
T1  
BZY97C180  
19 V, 3.42 A  
1 kV  
RM10  
180 V  
4
5
6
FL1  
D2  
MBR20100CT  
3KBP08M  
BR1  
FL2  
R8  
R9  
RTN  
100 7  
1 k7  
C10  
22 MF  
50 V  
VR2  
R10  
1N5248B  
18 V  
VR3  
BZX79-C22  
22 V  
73.2 k7  
R3  
R5  
3
2
2.0 M7 5.1 M7  
C11  
D1  
100 nF  
DL4937  
50 V  
R11  
D4 BAV19WS  
L1  
2 M7  
12 mH  
R16  
R18  
47 7  
R4  
R6  
680 7  
2.0 M7 6.8 M7  
R12  
5.1 k7  
C7  
100 nF  
25 V  
C2  
120 MF  
400 V  
D5  
U3B  
BAV19WS  
PC357A  
R1  
R2  
2.2 M7 2.2 M7  
U3A  
PC357A  
C4  
100 nF  
400 V  
D3  
BAV19WS  
U2A  
C1  
LTY817C  
F1  
4 A  
330 nF  
275 VAC  
U2B  
LTY817C  
R13  
5.1 7  
TOPSwitch-HX  
U1  
D
S
V
TOP260EN  
L
E
N
R14  
100 7  
D6  
1N4148  
CONTROL  
R19  
C
68.1 k7  
C18  
100 nF  
R15  
X
F
6.8 7  
C16  
90 - 265  
VAC  
R21  
1 k7  
1 MF  
C8  
100 nF  
50 V  
R7  
15 k7  
1%  
C9  
47 MF  
16 V  
50 V  
C3  
470 pF  
250 VAC  
C17  
33 MF  
35 V  
U4  
LM431  
2%  
R20  
10 k7  
L2  
Ferrite Bead  
PI-4998-021408  
Figure 44. 65 W, 19 V Power Supply Using TOP260EN.  
24  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
Key Application Considerations  
TOPSwitch-HX vs. TOPSwitch-GX  
features eliminate the need for additional discrete components.  
Other features increase the robustness of design, allowing cost  
savings in the transformer and other power components.  
Table 4 compares the features and performance differences  
between TOPSwitch-HX and TOPSwitch-GX. Many of the new  
TOPSwitch-HX vs. TOPSwitch-GX  
Function  
TOPSwitch-GX  
TOPSwitch-HX  
TOPSwitch-HX Advantages  
EcoSmart  
Linear frequency reduction to Multi-mode operation with  
Improved efficiency over load (e.g. at 25% load  
point)  
Improved standby efficiency  
Improved no-load consumption  
30 kHz (@ 132 kHz) for  
duty cycles < 10%  
linear frequency reduction to  
30 kHz (@ 132 kHz) and  
multi-cycle modulation  
(virtually no audible noise)  
Output Overvoltage  
Protection (OVP)  
Not available  
User programmable primary  
or secondary hysteretic or  
latching OVP  
Protects power supply output during open loop fault  
Maximum design flexibility  
Line Feed-Forward with Duty Linear reduction  
Cycle Reduction  
Dual slope reduction with  
lower, more accurate onset  
point  
Improved line ripple rejection  
Smaller DC bus capacitor  
Switching Frequency DIP-8  
Package  
132 kHz  
66 kHz  
Increased output power for given MOSFET size due  
to higher efficiency  
Lowest MOSFET On  
Resistance in DIP-8 Package  
3.0 Ω (TOP246P)  
1.8 Ω (TOP258P)  
Increased output power in designs without external  
heatsink  
I2f Trimming  
Not available  
5.6%  
-10% / +20%  
2%  
Increased output power for given core size  
Reduced over-load power  
Auto-restart Duty Cycle  
Reduced delivered average output power during  
open loop faults  
Frequency Jitter  
4 kHz @ 132 kHz  
2 kHz @ 66 kHz  
5 kHz @ 132 kHz  
2.5 kHz @ 66 kHz  
Reduced EMI filter cost  
Increased design margin  
Thermal Shutdown  
130 °C to 150 °C  
30%-100% of ILIMIT  
135 °C to 150 °C  
External Current Limit  
30%-100% of ILIMIT, additional  
trim at 0.7 × ILIMIT  
Reduced tolerances when current limit is set  
externally  
Line UV Detection Threshold 50 μA (2 MΩ sense  
25 μA (4 MΩ sense  
impedance)  
Reduced dissipation for lower no-load consumption  
impedance)  
Soft-Start  
10 ms duty cycle and current 17 ms sweep through multi-  
Reduced peak current and voltage component  
stress at startup  
Smooth output voltage rise  
limit ramp  
mode characteristic  
Table 4.  
Comparison Between TOPSwitch-GX and TOPSwitch-HX.  
25  
www.powerint.com  
Rev. F 01/09  
TOP252-262  
TOPSwitch-HX Design Considerations  
heat sinking, air circulation, etc.). The higher DCMAX of  
TOPSwitch-HX, along with an appropriate transformer turns  
ratio, can allow the use of a 80 V Schottky diode for higher  
efficiency on output voltages as high as 15 V (see Figure 41).  
Power Table  
The data sheet power table (Table 1) represents the maximum  
practical continuous output power based on the following  
conditions:  
Bias Winding Capacitor  
1. 12 V output.  
Due to the low frequency operation at no-load, a 10 μF bias  
winding capacitor is recommended.  
2. Schottky or high efficiency output diode.  
3. 135 V reflected voltage (VOR) and efficiency estimates.  
4. A 100 VDC minimum for 85-265 VAC and 250 VDC mini-  
mum for 230 VAC.  
5. Sufficient heat sinking to keep device temperature ≤100 °C.  
6. Power levels shown in the power table for the M/P package  
device assume 6.45 cm2 of 610 g/m2 copper heat sink area  
in an enclosed adapter, or 19.4 cm2 in an open frame.  
Soft-Start  
Generally, a power supply experiences maximum stress at  
start-up before the feedback loop achieves regulation. For a  
period of 17 ms, the on-chip soft-start linearly increases the  
drain peak current and switching frequency from their low  
starting values to their respective maximum values. This  
causes the output voltage to rise in an orderly manner, allowing  
time for the feedback loop to take control of the duty cycle.  
This reduces the stress on the TOPSwitch-HX MOSFET, clamp  
circuit and output diode(s), and helps prevent transformer  
saturation during start-up. Also, soft-start limits the amount of  
output voltage overshoot and, in many applications, eliminates  
the need for a soft-finish capacitor.  
The provided peak power depends on the current limit for the  
respective device.  
TOPSwitch-HX Selection  
Selecting the optimum TOPSwitch-HX depends upon required  
maximum output power, efficiency, heat sinking constraints,  
system requirements and cost goals. With the option to  
externally reduce current limit, an Y, E/L or M package  
TOPSwitch-HX may be used for lower power applications  
where higher efficiency is needed or minimal heat sinking is  
available.  
EMI  
The frequency jitter feature modulates the switching frequency  
over a narrow band as a means to reduce conducted EMI peaks  
associated with the harmonics of the fundamental switching  
frequency. This is particularly beneficial for average detection  
mode. As can be seen in Figure 45, the benefits of jitter increase  
with the order of the switching harmonic due to an increase in  
frequency deviation. Devices in the P, G or M package and  
TOP259-261YN operate at a nominal switching frequency of  
66 kHz. The FREQUENCY pin of devices in the TOP254-258 Y  
and E packages offer a switching frequency option of 132 kHz or  
66 kHz. In applications that require heavy snubber on the drain  
node for reducing high frequency radiated noise (for example,  
video noise sensitive applications such as VCRs, DVDs, monitors,  
TVs, etc.), operating at 66 kHz will reduce snubber loss, resulting  
in better efficiency. Also, in applications where transformer size is  
not a concern, use of the 66 kHz option will provide lower EMI  
and higher efficiency. Note that the second harmonic of 66 kHz  
is still below 150 kHz, above which the conducted EMI  
specifications get much tighter. For 10 W or below, it is possible  
to use a simple inductor in place of a more costly AC input  
common mode choke to meet worldwide conducted EMI limits.  
Input Capacitor  
The input capacitor must be chosen to provide the minimum  
DC voltage required for the TOPSwitch-HX converter to  
maintain regulation at the lowest specified input voltage and  
maximum output power. Since TOPSwitch-HX has a high  
DCMAX limit and an optimized dual slope line feed forward for  
ripple rejection, it is possible to use a smaller input capacitor.  
For TOPSwitch-HX, a capacitance of 2 μF per watt is possible  
for universal input with an appropriately designed transformer.  
Primary Clamp and Output Reflected Voltage VOR  
A primary clamp is necessary to limit the peak TOPSwitch-HX  
drain to source voltage. A Zener clamp requires few parts and  
takes up little board space. For good efficiency, the clamp  
Zener should be selected to be at least 1.5 times the output  
reflected voltage VOR, as this keeps the leakage spike  
conduction time short. When using a Zener clamp in a  
universal input application, a VOR of less than 135 V is  
recommended to allow for the absolute tolerances and  
temperature variations of the Zener. This will ensure efficient  
operation of the clamp circuit and will also keep the maximum  
drain voltage below the rated breakdown voltage of the  
TOPSwitch-HX MOSFET. A high VOR is required to take full  
advantage of the wider DCMAX of TOPSwitch-HX. An RCD  
clamp provides tighter clamp voltage tolerance than a Zener  
clamp and allows a VOR as high as 150 V. RCD clamp  
dissipation can be minimized by reducing the external current  
limit as a function of input line voltage (see Figures 23 and 36).  
The RCD clamp is more cost effective than the Zener clamp but  
requires more careful design (see Quick Design Checklist).  
Transformer Design  
It is recommended that the transformer be designed for  
maximum operating flux density of 3000 Gauss and a peak flux  
density of 4200 Gauss at maximum current limit. The turns  
ratio should be chosen for a reflected voltage (VOR) no greater  
than 135 V when using a Zener clamp or 150 V (max) when  
using an RCD clamp with current limit reduction with line  
voltage (overload protection). For designs where operating  
current is significantly lower than the default current limit, it is  
recommended to use an externally set current limit close to the  
operating peak current to reduce peak flux density and peak  
power (see Figures 22 and 35). In most applications, the tighter  
current limit tolerance, higher switching frequency and soft-start  
features of TOPSwitch-HX contribute to a smaller transformer  
when compared to TOPSwitch-GX.  
Output Diode  
The output diode is selected for peak inverse voltage, output  
current, and thermal conditions in the application (including  
26  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
80  
70  
60  
50  
40  
30  
Primary Side Connections  
Use a single point (Kelvin) connection at the negative terminal of  
the input filter capacitor for the TOPSwitch-HX SOURCE pin  
and bias winding return. This improves surge capabilities by  
returning surge currents from the bias winding directly to the  
input filter capacitor. The CONTROL pin bypass capacitor  
should be located as close as possible to the SOURCE and  
CONTROL pins, and its SOURCE connection trace should not  
be shared by the main MOSFET switching currents. All  
SOURCE pin referenced components connected to the MULTI-  
FUNCTION (M-pin), VOLTAGE MONITOR (V-pin) or EXTERNAL  
CURRENT LIMIT (X-pin) pins should also be located closely  
between their respective pin and SOURCE. Once again, the  
SOURCE connection trace of these components should not be  
shared by the main MOSFET switching currents. It is very  
critical that SOURCE pin switching currents are returned to the  
input capacitor negative terminal through a separate trace that  
is not shared by the components connected to CONTROL,  
MULTI-FUNCTION, VOLTAGE MONITOR or EXTERNAL  
CURRENT LIMIT pins. This is because the SOURCE pin is also  
the controller ground reference pin. Any traces to the M, V or X  
pins should be kept as short as possible and away from the  
DRAIN trace to prevent noise coupling. VOLTAGE MONITOR  
resistors (R1 and R2 in Figures 46, 47, 48, R3 and R4 in  
Figure 49, and R14 in Figure 50) should be located close to the  
M or V pin to minimize the trace length on the M or V pin side.  
Resistors connected to the M, V or X pin should be connected  
as close to the bulk cap positive terminal as possible while  
routing these connections away from the power switching  
circuitry. In addition to the 47 μF CONTROL pin capacitor, a  
high frequency bypass capacitor in parallel may be used for  
better noise immunity. The feedback optocoupler output  
should also be located close to the CONTROL and SOURCE  
pins of TOPSwitch-HX.  
20  
-10  
0
EN55022B (QP)  
EN55022B (AV)  
-10  
-20  
0.15  
1
10  
30  
Frequency (MHz)  
Figure 45a. Fixed Frequency Operation Without Jitter.  
80  
70  
60  
TOPSwitch-HX (with jitter)  
50  
40  
30  
20  
-10  
0
EN55022B (QP)  
EN55022B (AV)  
-10  
-20  
0.15  
1
10  
30  
Y-Capacitor  
Frequency (MHz)  
The Y-capacitor should be connected close to the secondary  
output return pin(s) and the positive primary DC input pin of the  
transformer.  
Figure 45b. TOPSwitch-HX Full Range EMI Scan (132 kHz With Jitter) With  
Identical Circuitry and Conditions.  
Heat Sinking  
Standby Consumption  
The tab of the Y package (TO-220C) and E package (eSIP-7C)  
and L package (eSIP-7F) are internally electrically tied to the  
SOURCE pin. To avoid circulating currents, a heat sink  
attached to the tab should not be electrically tied to any primary  
ground/source nodes on the PC board. When using a  
P (DIP-8), G (SMD-8) or M (DIP-10) package, a copper area  
underneath the package connected to the SOURCE pins will  
act as an effective heat sink. On double sided boards, topside  
and bottom side areas connected with vias can be used to  
increase the effective heat sinking area. In addition, sufficient  
copper area should be provided at the anode and cathode  
leads of the output diode(s) for heat sinking. In Figures 46 to 50  
a narrow trace is shown between the output rectifier and output  
filter capacitor. This trace acts as a thermal relief between the  
rectifier and filter capacitor to prevent excessive heating of the  
capacitor.  
Frequency reduction can significantly reduce power loss at light  
or no load, especially when a Zener clamp is used. For very  
low secondary power consumption, use a TL431 regulator for  
feedback control. A typical TOPSwitch-HX circuit automatically  
enters MCM mode at no load and the low frequency mode at  
light load, which results in extremely low losses under no-load  
or standby conditions.  
High Power Designs  
The TOPSwitch-HX family contains parts that can deliver up to  
333 W. High power designs need special considerations.  
Guidance for high power designs can be found in the Design  
Guide for TOPSwitch-HX (AN-43).  
TOPSwitch-HX Layout Considerations  
The TOPSwitch-HX has multiple pins and may operate at  
high power levels. The following guidelines should be  
carefully followed.  
27  
www.powerint.com  
Rev. F 01/09  
TOP252-262  
Isolation Barrier  
Y1-  
Capacitor  
C6  
Optional PCB slot for external  
heatsink in contact with  
SOURCE pins  
C2  
R4  
T1  
Input Filter  
Capacitor  
C10  
D3  
R9  
R3  
Output  
Rectifier  
D1  
J1  
Output Filter  
Capacitor  
Transformer  
+
C7  
S
S
S
S
D
HV  
U1  
-
C
C1  
L1  
M
JP1  
C4  
C3  
R8  
C5  
C8  
R1  
R2  
J2  
D2  
R11  
R10  
U3  
C9  
R12  
JP2  
U2  
Maximize hatched copper  
areas (  
) for optimum  
VR2  
heat sinking  
DC  
Out  
-
+
PI-4753-070307  
Figure 46. Layout Considerations for TOPSwitch-HX Using P-Package.  
Isolation Barrier  
C2  
Optional PCB slot for external  
heatsink in contact with  
Y1-  
Capacitor  
C6  
R6  
T1  
SOURCE pins  
R5  
Input Filter  
Capacitor  
Output  
Rectifier  
R12  
J1  
D1  
Output Filter  
Capacitor  
+
D3  
Transformer  
HV  
-
C7  
D
S
S
U1  
S
C
X
V
L1  
C1  
S
S
JP1  
C4  
R8  
R7  
C3  
C9  
C5  
R13  
R14  
D2  
C8  
J2  
U3  
R15  
R1  
R3  
R2  
R4  
R9  
JP2  
U2  
VR2  
R16  
R17  
Maximize hatched copper  
areas (  
) for optimum  
heat sinking  
-
+
DC  
Out  
PI-4752-070307  
Figure 47. Layout Considerations for TOPSwitch-HX Using M-Package.  
28  
Rev. F 01/09  
www.powerint.com  
TOP252-262  
Isolation Barrier  
C2  
Y1-  
Capacitor  
C6  
R4  
T1  
Input Filter  
Capacitor  
R3  
R12  
C10  
Output  
Rectifier  
D1  
J1  
Output Filter  
Capacitor  
HS1  
D3  
+
Transformer  
HV  
-
D
V
U1  
C7  
S
X
F
L1  
C
C1  
JP1  
C4  
R10  
R7  
R2  
R13  
C5  
C9  
R1  
U3  
D2  
C8  
JP2  
U2  
J2  
R3  
R4  
R15  
R17