The DH321 integrated block can be replaced by the FSDL321 model. DH321 is the latest single chip low-power off-line switching power supply integrated circuit developed by Fairchild. The power supply voltage output control mode is current type pulse width adjustment (pwm), which is called \"green chip\". The integrated circuit is an 8-pin dual-in-line (8DIP) package, and ① the pin is the ground terminal;
② foot is the power end;
③ Foot is the feedback input end;
④ the foot is the limit current adjustment end of the switching tube;
⑤ Pin is the starting voltage access end directly 300 volts, 6, 7, 8 and the transformer line main coil is connected to 300 volts.