A single-stage off-line LED driver IC with hysteretic power factor correction control

An off-line light-emitting diode (LED) driver circuit that adopts a modified boost converter architecture with hysteric current control for power factor correction (PFC) is described. It removes a bulky electrolytic capacitor, improving the lifetime and enabling direct regulation of the LED current. To reduce the size and manufacturing cost of the LED modules, the driver circuit is designed as a custom integrated circuit (IC) fabricated in a 1.0 μm 650V trench-isolated BCDMOS process with only a few external components. The initial prototype, however, showed LED´s reverse recovery current and inductor´s self-resonance problem due to the high-frequency, hard switching operation of the control circuit. A revised prototype with additional off-chip components demonstrated the feasibility of the proposed circuit and the performance of 96.3% peak power factor and 84.5% efficiency, when delivering 18W to a 360V LED string from a 220V AC supply.