AN4129 - Fairchild Semiconductor

AN4129 Green Current Mode PWM Controller FAN7601

1. Start-up Circuit And Reference The FAN7601 contains a start-up switch to reduce power loss in the external start-up circuit of conventional PWM converters. The internal start-up circuit charges the Vcc capacitor with a 1mA current source if the line is connected until the soft start is completed as shown in Fig. 2. The soft start function starts when the .

Features

of the FAN7601. This device is a BCDMOS programmable frequency current mode PWM controller which is designed for off-line adapter applications and auxiliary power supplies. To reduce power loss at light and no load, the FAN7601 operates in burst mode and it includes a start-up switch to reduce the losses in the start-up circuit. Because of the internal start-up switch and burst mode operation, it is possible to supply an output power of 0.5W with under 1W input power when the input line voltage is 265V. On no load condition, input power is under 0.3W. The FAN7601 offers a latch protection pin .