The SM5911 is a high precision non-isolated buck driver with active PFC, specially designed for universal input offline constant current LED lighting power supplies in under 250mA output current. The driver with on-chip PFC circuit achieves high power factor and low THD. Operating in critical conduction mode, the power MOSFET switching loss is reduced and the inductor is fully utilized. The SM5911 integrates a 500V power MOSFET with few external components, the LED output current can be precisely controlled. The inductor current is sensed during the whole switching cycle.
So it achieves high precision output current control, and excellent line regulation and load regulation. The SM5911 offers rich protection functions to improve the system reliability, including LED open circuit protection, LED short circuit protection, VCC under voltage protection, CS resistor open circuit protection and cycle by cycle current limit. All the protection functions are auto-recovery. The system reliability is further improved by the thermal regulation function. The output current is reduced when the driver is over temperature.