The present invention is directed to circuit that provides a bias voltage to a switching power supply. Devices such as computers, lamp ballasts, battery chargers, and displays use a switching power supply. Various types of switching power supplies are available, but each needs a bias voltage to power the control circuit. The bias voltage, typically 12 volts at 10-100 ma, is derived from an input power source, which may be a main at 120 or 220-240 volts, 50-60 hertz.
The presently available bias circuits can be improved by reducing their size, cost and power consumption.