Patent ID: 6421260
Filing Date: 2002-07-16
Classification: H02M

Abstract:
A power supply circuit, configured to control operation of a load, comprising:(a) a converter configured to convert a DC signal to an AC signal, the converter comprising a pair of switches serially connected between a bus conductor at a DC bus voltage and a reference conductor, a voltage between a reference terminal and a control terminal of each switch determining the conduction state of the associated switch, the respective reference terminals of the switches being connected together at a common node through which the AC signal current flows, and the respective control terminals of the switches being connected together at a control node; (b) a drive circuit connected to the converter to control operation of the converter, the drive circuit comprising a driving inductor having a voltage induced therein that is proportional to an instantaneous rate of change of the AC signal current, the driving inductor providing a driving energy for operation of the drive circuit, and the drive circuit controlling the conduction states of the switches; and (c) a shutdown circuit connected to the drive circuit and configured to directly receive a digital signal to at least one of selectively turn off or allow normal operation of the converter, the shutdown circuit comprising a diode and a switch, wherein a low impedance conduction path is provided between the control node and the common node to the reference conductor thereby resulting in the control terminals of the switches being at approximately the same potential as the reference terminals, and the load is turned off and minimal current is drawn from the DC signal when the converter is turned off.