SD4938 is a current mode PWM controller with 150V MOSFET used for SMPS.

    SD4938 integrates high-voltage start-up circuit. It enters burst mode at light load to reduce the system standby power dissipation; the frequency reduction function optimizes the conversion efficiency at light load; the soft startup function reduces the stress of device to avoid transformer saturation.

    SD4938 features various protections, including VDD undervoltage protection, VDD overvoltage protection, lead edge blanking, over current protection, over temperature protection, etc. Meanwhile, if any protection occurs, the circuit will continue to restart automatically until the system recovers.