Patent ID: 8422253
Filing Date: 2013-04-16
Classification: H02M

Abstract:
1. A synchronous timing pulse generation circuit, applicable to a switching power supply, wherein the switching power supply has a primary side and a secondary side, the switching power supply enables a power to be selectively input or not input to the primary side through a pulse-width-modulation signal, the synchronous timing pulse generation circuit is used to generate a starting pulse of the pulse-width-modulation signal, the synchronous timing pulse generation circuit comprising: a time delay unit, for outputting a control signal after delaying the starting pulse for a predetermined time; a timing pulse regulation unit, for enabling a constant current source to selectively charge the timing pulse regulation unit according to the control signal, and accordingly outputting a timing pulse signal; and a synchronization control unit, for outputting the starting pulse according to a discharging time signal of the secondary side and the timing pulse signal, wherein the timing pulse signal has a rising edge, the discharging time signal has a falling edge, a triggering time of the starting pulse is synchronized to one occurring later of the rising edge of the timing pulse signal and the falling edge of the discharging time signal in the same period, and the starting pulse is used to determine a pulse starting time of the pulse-width-modulation signal.