SG6901A

SG6901A — CCM PFC / Flyback PWM Combination Controller February 2009 SG6901A CCM PFC/Flyback PWM Combination Controller Features ƒ Interleaved PFC/PWM Switching ƒ Low Startup and Operating Current ƒ Innovative Switching Charge Multiplier Divider ƒ Multi-vector Control for Improved PFC Output Transient Response ƒ Average-Current-Mode Control for PFC ƒ Programmable Two-Level PFC Output Voltage Protections ƒ PFC and PWM Feedback Open-Loop Protection ƒ Cycle-by-Cycle Current Limiting for PFC/PWM ƒ Slope Compensation for PWM ƒ H/L Line Over-Power Compensation for PWM ƒ Brownout Protection ƒ Over-Temperature Protection (OTP) Applications ƒ Switching Power Supplies with Active PFC and Standby Power ƒ High-Power Adaptors Description The highly integrated SG6901A is designed for power supplies with boost PFC and flyback PWM. It requires very few external components to achieve versatile protections. It is available in a 20-pin SOP package. A proprietary interleave-switching feature synchronizes the PFC and PWM stages and reduces switching noise. For PFC stage, the proprietary multi-vector control scheme provides a fast transient response in a lowbandwidth PFC loop, in which the overshoot and undershoot of the PFC voltage are clamped. If the feedback loop is broken, the SG6901A shuts off PFC to prevent extra-high voltage on output. For the flyback PWM, the synchronized slope compensation ensures the stability of the current loop under continuous-conduction-mode operation. Built-in l...