Patent ID: 6534967
Filing Date: 2003-03-18
Classification: G01R

Abstract:
A current sensor for measuring load current flowing through a load driven by a dual totem power stage, the dual totem power stage having four power devices, at least two of which are controlled by pulse width modulation (PWM) control signals to change current paths of the load current, the current sensor comprising:a transformer including a secondary winding having a number N of turns, the transformer also including a primary winding comprising four separate primary winding sections each coupled in series with a different one of the four power devices of the dual totem power stage, and wherein different ones of the four primary winding sections have different numbers of turns such that different turns ratios result between the primary winding and the secondary winding for different current paths and thus generating a modulated signal on the secondary winding; and measurement circuitry coupled to the secondary of the transformer, the measurement circuitry demodulating the modulated signal on the secondary winding to provide a load current output indicative of a level of current through the load.