The control circuit adopts high performance current mode controller UC3843 as the control chip. UC3843 is a high-performance fixed-frequency current-mode controller designed for off-line and dc-dc converter applications, providing designers with cost-effective solutions that require minimal external components. The internal IC has a fine-tuned oscillator, a reference for accurate duty cycle control, temperature compensation, and a high-gain error amplifier. Current sampling comparator and high current totem pole output are ideal devices for driving MOSFET. Its protection features include input and reference undervoltage locking hysteresis, periodic current limitation, programmable output dead zone time, and a latch for monopulse metering.