The S3843 is fixed Current PWM controller for Off-line and DC-DC converter applications. The internal 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. Protection circuitly includes built in under voltage lockout and current limiting. S3843 have UVLO threshold of 8.4V(on) and 7.6V(off). S3843 can operate within 100% duty cycle.