A synchronous rectification device comprises a synchronous rectification tube, a drive 
control circuit, a Vcc 
capacitor and a charging circuit for charging a grid 
electrode of the synchronous rectification tube. The Vcc 
capacitor is charged through the charging circuit by means of reverse 
voltage applied to the synchronous rectification device, and when the 
voltage of the Vcc 
capacitor is detectedto rise to the upper 
limit value Vcc_H of the Vcc capacitor, charging of the Vcc capacitor is stopped; and when the Vcc 
voltage is detected to be reduced to a 
lower limit value Vcc L, starting to charge the Vcc capacitor is carried out, so that a switching tube of the charging circuit works in an intermittent and complete conduction state. By controlling the upper limit and the 
lower limit of theVcc voltage, the charging circuit is promoted to work intermittently, and the 
power consumption of the power supply circuit is greatly reduced; in a standby state, when the working frequency is lower, the 
current consumption of the Vcc end is extremely low, the working intermittent time of the charging circuit is longer, the 
power consumption is further reduced, and the heating and standby powerconsumption is reduced.