www.fairchildsemi.com
KA3842B/KA3843B/KA3844B/
KA3845B
SMPS Controller
Features
•
•
•
•
Low Start up Current
Maximum Duty Clamp
UVLO With Hysteresis
Operating Frequency up to 500KHz
Description
The KA3842B/KA3843B/KA3844B/KA3845B are fixed
frequency current-mode PWM controller. They are
specially designed for Off - Line and DC-to-DC converter
applications with minimum external components. These
integrated circuits feature a trimmed oscillator for precise
duty cycle control, a temperature compensated reference,
high gain error amplifier, current sensing comparator and a
high current totempole output for driving a power MOSFET.
The KA3842B and KA3844B have UVLO thresholds of
16V (on) and 10V (off). The KA3843B and KA3845B are
8.5V (on) and 7.9V (off). The KA3842B and KA3843B can
operate within 100% duty cycle. The KA3844B and
KA3845B can operate with 50% duty cycle.
8-DIP
1
14-SOP
1
Internal Block Diagram
Rev. 1.0.2
©2002 Fairchild Semiconductor Corporation
FAIRCHILD [ FAIRCHILD SEMICONDUCTOR ]
