POWER SUPPLY DRIVE CIRCUIT, CHIP AND METHOD

Disclosed is a power supply drive circuit, chip and method. In each switching-on cycle, the charging demand is considered. If the current switching-on cycle requires charging, after the drive tube is completely switched on in the current switching-on cycle, the sampling switch tube is switched off and the charging switch tube is switched on for using a small current which flows through the drive tube in the early stage of the switching-on cycle for charging. In the later stage of the current switching-on cycle, the sampling switch tube is switched on and the charging switch tube is switched off, such that the current outputted by the drive tube flows through the current sampling switch tube according to the normal path. In this way, the power supply voltage never changes with the output power, the cumbersome design and debugging of the power supply circuit are avoid.