SG6902 is a controller designed for power supplies that consist of boost PFC and flyback PWM. It requires few external components to achieve green-mode operation and versatile protections and compensations. The proprietary interleave switching synchronizes the PFC and PWM stages and reduces switching noise. At light loads, PFC stage is turned off to save power and the PWM switching frequency increases.
The document details the use of the SG6902 integrated circuit to control a CCM PFC and Flyback/PWM power supply. It highlights features such as interleaved switching, green-mode operation at light loads, multi-vector control for improved transient response, and various protection mechanisms including over-temperature and cycle-by-cycle current limiting.
The guide includes specific design equations and component selection procedures for the PFC inductor, boost capacitor, and resistors required to set switching frequency and brownout thresholds. It also explains the power-on sequence between the PWM and PFC stages.
| Start Threshold Voltage | 16V |
|---|---|
| Minimum Operating Voltage | 10V |
| Package Types | 20-Pin SOP and SSOP |
The recommended range for the switching frequency is 33kHz to 100kHz.
The PFC stage is disabled when the feedback voltage of the FBPWM pin falls below a threshold between 1.95V and 2.45V.
At light loads, the PFC stage is turned off to save power and the PWM switching frequency is decreased.