System for increasing the definition in converting a digital datum in a PWM signal for driving a full-bridge output stage

摘要

The definition of conversion of a digital value in a PWM signal using an N-bit up/down counter is improved by increasing the dimension of the input data to N+2 bits. This is done using the two Lsb's of the N+2 input data for selecting one among three intermediate levels between two consecutive values of an N-bit dynamic, according to a predefined table of combinations. The converter may still use an N-bit comparator. The system is particularly useful in driving a multi-phase brushless DC motor with each phase-winding singularly driven through a full-bridge output stage.