Patent ID: 9054705
Filing Date: 2015-06-09
Classification: H02M,H03K

Abstract:
1. A source driving circuit configured for a switching power circuit, the source driving circuit comprising: a) a source transistor coupled between a source of a main power transistor and ground, wherein said source transistor is controllable by a pulse-width modulation (PWM) control signal; b) said main power transistor being configured to be on when said source transistor is on and a gate-source voltage of said main power transistor exceeds a conduction threshold voltage; c) a source diode having an anode coupled to said main power transistor source, and a cathode coupled to a delay circuit and to a power supply capacitor, wherein said power supply capacitor is not connected to a gate of said main power transistor; and d) said delay circuit being coupled to said power supply capacitor and said main power transistor gate, and being configured to turn off said main power transistor after a delay time from said source transistor being turned off has elapsed, wherein said power supply capacitor is charged during said delay time such that a voltage across said power supply capacitor is at least a level of a reference voltage.