FAN400C

FAN400C — Low-Power, Green-Mode, PWM Flyback Power Controller without Secondary Feedback (CC) www.DataSheet4U.com September 2008 FAN400C — Low-Power, Green-Mode, PWM Flyback Power Controller without Secondary Feedback (CC) Features ƒ Linearly Decreasing PWM Frequency ƒ Green Mode Under Light-Load and Zero-Load Conditions Circuitry Description This highly integrated PWM controller provides several features to enhance the performance of low-power flyback converters. To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load and zero-load conditions. This green mode enables the power supply to meet international power conservation requirements. Another advantage of the FAN400C is that the typical startup current is only 8μA, while the typical operating current can be as low as 3.6mA. A large startup resistance can be used to achieve higher power conversion efficiency. FAN400C integrates a frequency-hopping function internally to reduce EMI emissions with minimum line filters. Built-in synchronized slope compensation maintains the stability of peak current-mode control. Proprietary internal compensation ensures constant output power limiting over a universal range of AC input voltages, from 90VAC to 264VAC. The FAN400C provides many protection functions. Pulse-by-pulse current limiting ensures constant output current, even if a short circuit occurs. The internal protection...