Switching power supply and power transistor drive circuit for switching power supply

Abstract

The present invention discloses a switching power supply and a power transistor driving circuit for the switching power supply, comprising: a logic control module for generating a turn-on control signal and a turn-off control signal based on a received switching control signal; a driving module for generating a gate driving signal for a power transistor based on the turn-on control signal and the turn-off control signal, wherein the gate driving signal has a first slope and a second slope that are time-dependent during a conduction process of the power transistor, and the first slope is greater than the second slope; a voltage detection module for detecting a switch node voltage when the power transistor is turned on to obtain a voltage detection signal; a variable slope control module for comparing the voltage detection signal with a reference voltage, and adjusting a time length of the first slope of the gate drive signal in a next switching cycle based on a comparison result, so as to reduce a resonant voltage during the conduction process of the power transistor without increasing a conduction loss of the power transistor, while balancing high-efficiency driving and circuit reliability.

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