KA3843AC Datasheet, PDF (1/6 Pages) Fairchild Semiconductor – SMPS Controller

KA3843AC
SMPS Controller
Features
• Low start current 0.2mA (typ)
• Operating range up to 500kHz
• Cycle by cycle current limiting
• Under voltage lock out with hysteresis
• Short shutdown delay time: typ.100ns
• High current totem-pole output
• Output swing limiting: 22V
www.fairchildsemi.com
Description
The KA3843AC are fixed PWM controller for Off-Line and
DC to DC converter applications. The internal circuits
include UVLO, low start up current circuit, temperature
compensated reference, high gain error amplifier, current
sensing comparator, and high current totem-pole output for
driving a POWER MOSFET. Also KA3843AC provide low
start up current below 0.3mA and short shutdown delay
time typ. 100ns. The KA3843AC is 8.4V(on) and 7.6V(off).
The KA3843AC can operate within 100% duty cycle.
8-DIP
1
8-SOP
1
Internal Block Diagram
VREF 8
Internal
Bias
5V
VREF
SET/
RESET
Good LOGIC
UVLO
VFB 2
COMP 1
1/2VREF
Error Amp
+
-
1/3
1V
C.S _PWM
Comp. _LATCH
R
S
C.S 3
T
RT/CT 4
OSCILLATOR
©2005 Fairchild Semiconductor Corporation
7 VCC
29V
5 GND
7
PWR
VC
22V 6 OUTPUT
5
PWR
GND
Rev. 1.0.1