Patent ID: 6809560
Filing Date: 2004-10-26
Classification: G01R,H02M,Y02B

Abstract:
A circuit for sensing a voltage across a power switch, said power switch having a first current handling terminal, a second current handling terminal and a control terminal receiving a first control signal, said first control signal turning said power switch on and off to generate a switching voltage at said first current handling terminal, said circuit comprising:a transmission gate having an input terminal coupled to said first current handling of said power switch, an output terminal, and a control terminal, said control terminal coupled to receive a signal corresponding to said first control signal such that said transmission gate is turned on whenever said power switch is turned on, said output terminal providing a sampled voltage indicative of the voltage across said power switch when said power switch is turned on; a low pass filter having an input terminal coupled to said output terminal of said transmission gate and an output terminal providing a filtered voltage; and a comparator having a first and second input terminals coupled to receive said filtered voltage and a reference voltage, said comparator providing an output signal having a first value when said filtered voltage is less than said reference voltage and a second value when said filtered voltage is greater than said reference voltage.