AN4129 Overview
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 pleted as shown in Fig. The soft start function starts when the Vcc voltage reaches the start threshold voltage(typically 12V) and...