Patent ID: 6788557
Filing Date: 2004-09-07
Classification: H02M

Abstract:
A DC-DC converter having first and second input terminals to which an input DC voltage is coupled and two output terminals where the output DC power is provided, comprising:a transformer comprising a primary winding, a secondary winding, and an auxiliary winding, each winding having a first and second end; said secondary winding coupled to said output terminals; a first switch connected in series with said primary winding across said first and second input terminals; said first switch alternately being switched on and off as a function of a control signal; a capacitor connected in series with a first diode and a second switch between said first and second input terminals; and a charging circuit for charging said capacitor to a predetermined value by said auxiliary winding; wherein said second switch is switched on when said input DC voltage is at or below a predetermined threshold such that said capacitor provides hold-up time for said converter.