Transition-mode PFC controller for compact power stages
The STMicroelectronics L6564D is a transition-mode (also called critical-conduction-mode) Power Factor Correction controller designed for boost pre-regulators in AC-DC power supplies. It operates in Discontinuous (Transition) mode, which simplifies the control loop and reduces the boost inductor size compared to continuous-conduction designs. The part integrates the control logic, a high-voltage startup circuit, and a totem-pole gate driver on a single die. The supply voltage range of 10.3 V to 22.5 V covers the typical bias rail from an auxiliary winding or a downstream regulator. The 90 µA startup current allows the controller to charge its Vcc capacitor quickly from a high-voltage startup resistor without excessive standby loss. The operating temperature range of -25°C to 125°C covers industrial environments. The surface-mount package is suited for automated assembly lines.
The part is ROHS3 compliant.
Design-in notes for the boost PFC stage
The L6564D is designed for boost PFC topologies. Transition-mode operation eliminates reverse-recovery losses in the boost diode. The 90 µA startup current allows a high-value startup resistor (typically several hundred kΩ) from the rectified DC bus, minimizing continuous power dissipation in the resistor after the auxiliary winding takes over. The 10.3 V to 22.5 V supply range gives headroom for the Vcc rail to ride through line dips without triggering undervoltage lockout.