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CS52845ED14 参数 Datasheet PDF下载

CS52845ED14图片预览
型号: CS52845ED14
PDF下载: 下载PDF文件 查看货源
内容描述: 电流模式PWM控制电路与50 %最大占空比 [Current Mode PWM Control Circuit with 50% Max Duty Cycle]
分类和应用:
文件页数/大小: 6 页 / 145 K
品牌: CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
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CS52845
CS52845
Current Mode PWM Control Circuit
with 50% Max Duty Cycle
Description
The CS52845 provides all the nec-
essary features to implement off-
line fixed frequency current-mode
control with a minimum number
of external components.
The CS52845 incorporates a new
precision temperature-controlled
oscillator to minimize variations in
frequency. An internal toggle flip-
flop, which blanks the output
every other clock cycle, limits the
duty-cycle range to less than 50%.
An undervoltage lockout ensures
that V
REF
is stabilized before the
output stage is enabled. In the
CS52845 turn on is at 8.4V and
turn off at 7.6V.
Other features include low start-up
current, pulse-by-pulse current lim-
iting, and a high-current totem pole
output for driving capacitive loads,
such as gate of a power MOSFET.
The output is low in the off state,
consistent with N-channel devices.
Features
s
Optimized for Off-line
Control
s
Temperature
Compensated Oscillator
s
50% Maximum Duty-cycle
Clamp
s
V
REF
Stabilized before
Output Stage is Enabled
s
Low Start-up Current
s
Pulse-by-pulse Current
Limiting
s
Improved Undervoltage
Lockout
s
Double Pulse Suppression
s
1% Trimmed Bandgap
Reference
s
High Current Totem Pole
Output
Absolute Maximum Ratings
Supply Voltage (I
CC
<30mA) ..........................................................Self Limiting
Supply Voltage (Low Impedance Source)...................................................30V
Output Current ...............................................................................................±1A
Output Energy (Capacitive Load) .................................................................5µJ
Analog Inputs (V
FB
, V
SENSE
)...........................................................-0.3V to 5.5V
Error Amp Output Sink Current...............................................................10mA
Lead Temperature Soldering
Reflow (SMD styles only) ...........60 sec. max above 183°C, 230°C peak
Block Diagram
Package Options
8L SO Narrow
COMP
1
2
3
4
8
7
6
5
V
REF
V
CC
V
OUT
Gnd
V
CC
V
CC
Undervoltage Lock-out
V
CC
Pwr
V
FB
Sense
34V
Gnd
8.4V/7.6V
V
FB
Error
Amplifier
-
+
2.50V
R
R
Set/
Reset
5.0 Volt
Reference
Internal
Bias
V
REF
OSC
14L SO Narrow
COMP
1
NC
2
V
FB
3
NC
4
Sense
5
Pwr Gnd
14
13
12
11
10
9
8
COMP
V
REF
Undervoltage
Lockout
V
REF
NC
V
CC
V
CC
Pwr
V
OUT
Gnd
Pwr Gnd
OSC
Oscillator
Toggle
Flip-Flop
S
R
NOR
V
OUT
2R
R
Sense
1V
NC
6
OSC
7
PWM
Current
Sensing Latch
Comparator
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
Rev. 3/4/99
1
A
®
Company