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The CS52843 provides all the nec-
essary features to implement off-
line fixed frequency current-mode
control with a minimum number
of external components.
The CS52843 incorporates a new
precision temperature-controlled
oscillator to minimize variations in
frequency. An undervoltage lock-
out ensures that V
REF
is stabilized
before the output stage is enabled.
In the CS52843 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.
1
Features
V
CC
Gnd
COMP
OSC
Sense
V
REF
ENABLE
IBias
NOR
S
R
PWM
CCurrent
R
2 R
1V
AmError
-
+
2.50V
Set/
V
CC
Undervoltage Lock-out
34V
8.4V/7.6V
R
R
V
FB
V
CC
Pwr
V
OUT
Pwr Gnd
Oscillator
R5.0 Volt
I
Optimized for Off-line
Control
Internally Temperature
Compensated Oscillator
V
Stabilized before
Output Stage is Enabled
Very Low Start-up Current
300 μA (typ)
Pulse-by-pulse Current
Limiting
Improved Undervoltage
Lockout
Double Pulse Suppression
2% 5 Volt Reference
High Current Totem Pole
Output
I
I
I
I
I
I
I
I
Package Options
8L SO Narrow
C
Current Mode PWM Control Circuit
CS52843
Description
Block Diagram
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
1
7
8
2
3
4
5
6
COMP
V
FB
Sense
OSC
V
REF
V
CC
V
OUT
Gnd
A
Company
10
7
14
13
12
8
1
2
3
4
5
6
11
9
COMP
NC
V
FB
NC
Sense
NC
OSC
V
REF
NC
V
CC
V
CC
Pwr
V
OUT
Pwr Gnd
Gnd
14L SO Narrow
Rev. 12/23/97
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