TNY253/254/255
PI–2253-062398
V
EN
时钟
DC
最大
V
IN
0V
IDRAIN
V
漏
0V
0
VDRAIN
.2
.4
.6
.8
1
时间(ms)
图7的TinySwitch上电时序图。
PI-2261-061198
PI–2251-062398
图6的TinySwitch工作在轻载。
V
IN
旁路引脚电容
The BYPASS pin uses a small 0.1 µF ceramic capacitor for
去耦的TinySwitch的内部电源。
12 V
0V
应用实例
电视待机
的TinySwitch是低成本,高效率的理想解决方案
在消费电子产品中使用的备用电源
such as TVs. Figure 9 shows a 7.5 V, 1.3 W flyback circuit that
uses TNY253 for implementing a TV standby supply. The circuit
从直流高电压已经可从操作
main power supply. This input voltage can range from 120 to
375 VDC depending on the input AC voltage range that the TV
is rated for. Capacitor C1 filters the high-voltage DC supply,
而且是唯一的必要,如果有一个长的迹线长度从
源的直流电源到电视待机电路的输入端。
高压DC总线被施加到串联组合
of the primary winding of T1 and the integrated high-voltage
MOSFET inside the TNY253. The low operating frequency of
the TNY253 (44 kHz), allows a low cost snubber circuit C2 and
R1 to be used in place of a primary clamp circuit. In addition
以限制漏极关断电压尖峰控制在安全值,
RC缓冲还通过降低辐射降低视频噪音
在dv / dt的漏极电压波形,这对视频的关键
应用,例如电视和录像机。在固定频率PWM
和RCC电路,使用一个缓冲的将导致不期望
能固定的交流开关损耗,是独立的负载。该
上的TinySwitch ON / OFF控制消除了这个问题
通过缩放的有效开关频率,因此,
VDRAIN
12 V
0V
0
100
200
300
400
500
时间(ms)
图8的TinySwitch掉电时序图。
线性开关损耗与负载。的这样的效率
供应保持相对稳定下来的瓦的一小部分
输出负载。
The secondary winding is rectified and filtered by D1 and C4 to
create the 7.5 V output. L1 and C5 provide additional filtering.
该输出电压由光耦合器之和来确定
U2 LED forward drop (~ 1 V) and Zener diode VR1 voltage.
The resistor R2, maintains a bias current through the Zener to
提高电压容差。
10 W待机
The TNY255 is ideal for standby applications that require up
to 10 W of power from 230 VAC or 100/115 VAC with doubler
circuit. The TNY255 operates at 130 kHz as opposed to 44 kHz
for TNY253/254. The higher frequency operation allows the
REV ê
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