ANALOG MULTPLEX FOR DETECTING MAGNITUDE AND SENSE OF CURRENT FLOWING THROUGH H-BRIDGE STAGE BY USING SINGLE DETECTION RESISTOR

摘要

PURPOSE: To accurately detect the magnitude and sense of current by providing a multiplexer with a single detecting resistor connected between the common virtual ground node of a drive bridge circuit and the real ground node. CONSTITUTION: An H-bridge stage for driving induction load L is composed of four switches SW1-SW4 driven by drive signals IN1 and inversion signals, and it switches the load functionally as the function of a duty cycle. The control of the load L is performed by detecting the magnitude and the sense (direction) of the current flowing through the load L. Moreover, an analog multiplex MPX made of two switches SWA and SWB adds this output signal to the next converter C. Then, the output amplitude of this MPX is proportionate to the quantity of a current flowing through the load L, and this polarity is decided by the polarity of the voltage Vref added to the other output of that comparator C.