Patent ID: 7518430
Filing Date: 2009-04-14
Classification: H02M,Y02B

Abstract:
1. An over-voltage protection apparatus for generating a regulated DC output voltage at an output node which is arranged to be coupled to a device powered thereby comprising: a DC-DC converter which is operative to generate a regulated output voltage derived from a supply voltage, said DC-DC converter having a pulse width modulation (PWM) generator which generates a PWM switching signal that switchably controls operation of a switching circuit containing first and second electronic power switching devices coupled between a power supply terminal to which said power supply voltage is coupled and a reference voltage terminal to which a reference voltage is coupled, said first and second electronic power switching devices having a common node there between coupled through an inductance to said output node; and a by-pass circuit, having an input connected to said common node and an output connected to a control input of said second electronic power switching device, and being operative, in response to detecting a voltage at said common node indicative of an effective short circuit through said first switching device between said power supply terminal and said common node, to turn on said second electronic power switching device, so as to provide a by-pass current flow path from said common node to said reference voltage terminal, and thereby prevent an over-voltage from being applied to said output node and said powered device.