Patent ID: 6320370
Filing Date: 2001-11-20
Classification: G01R

Abstract:
A circuit for measuring current flowing through a load driven by a pulse width modulation (PWM) circuit in response to PWM control signals, the circuit for measuring comprising:a transformer having primary and secondary windings, the primary winding being connected to the load;flux cancellation circuitry coupled to the secondary winding and adapted to apply a cancellation current to the secondary winding, the flux cancellation circuitry providing an output which is indicative of a level of current through the load;a load current output indicative of the level of current through the load;an inverter coupled to the flux cancellation circuitry output and providing an inverted flux cancellation circuitry output;a first switch selectively coupling the flux cancellation circuitry output to the load current output in response to a first signal generated as a function of the PWM control signals; anda second switch selectively coupling the inverted flux cancellation circuitry output to the load current output in response to a second signal generated as a function of the PWM control signals.