Isolated gate driver adapted for PWM-based switching power supply

摘要

An isolated gate driver including a driving control circuit, an isolated transformer, an anti-circuit and a secondary processing circuit is provided. The driving control circuit is configured to generate a driving PWM signal for driving a power switch tube. The isolated transformer has a primary winding and a secondary winding. The anti-circuit is connected between the driving control circuit and the primary winding of the isolated transformer, and is configured to suppress a variation of an induced voltage in the secondary winding of the isolated transformer when a duty cycle of the driving PWM signal is sharply decreased. The secondary processing circuit is connected in parallel with the secondary winding of the isolated transformer, and is configured to perform a voltage clamping action on a gate-source voltage of the power switch tube when the duty cycle of the driving PWM signal is sharply decreased.

主权项

1. An isolated gate driver, comprising:
a driving control circuit, configured to generate a driving pulse-width-modulation (PWM) signal for driving a power switch tube; an isolated transformer, having a primary winding and a secondary winding; an anti-circuit, connected between the driving control circuit and the primary winding of the isolated transformer, the anti-circuit comprising a first diode and a capacitor which is clamped to a forward bias voltage of the first diode, and configured to suppress a variation of an induced voltage in the secondary winding of the isolated transformer when a duty cycle of the driving PWM signal is sharply decreased, wherein the first diode and the capacitor are connected in parallel; and a secondary processing circuit, connected in parallel with the secondary winding of the isolated transformer, configured to perform a voltage clamping action on a gate-source voltage of the power switch tube when the duty cycle of the driving PWM signal is sharply decreased.