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.