Flyback switching power supply circuit and backlight driving device using the same

摘要

A flyback switching power supply circuit and a backlight driving device applying same. The flyback switching power supply circuit comprises: a transformer (200), comprising a primary winding, a secondary winding, and an auxiliary winding arranged at one side of the primary winding; an output rectifier (D2), connected to an output terminal of the flyback switching power supply circuit from the secondary winding of the transformer; a switch transistor (Q1), used for controlling the voltage on the primary winding; a controller (100), used for providing a pulse width modulated signal to drive a gate electrode of the switch transistor; a clamp delay circuit (300), used for clamping the gate electrode potential as a low potential, so that the switch transistor is turned on at the trough of the drain potential vibration damping of the switch transistor. Arranging a clamp delay circuit within the present switching power supply circuit and adding an auxiliary winding within the transformer enables the switch transistor to be turned on at the trough of the drain potential vibration damping of the switch transistor, thereby reducing switching losses of the switch transistor.