Driver Circuit Overcurrent Protection via PWM Signal Counting

The patent accumulates overcurrent detection signals over multiple PWM periods before triggering protection. By preliminarily counting the number of overcurrent detections (using a counter) and comparing against a threshold, the system determines whether overcurrent is genuine or transient noise before taking protective action. This preliminary assessment mechanism resolves the contradiction by distinguishing true overcurrent from noise-induced false positives without introducing a mask time that would allow harmful current to continue flowing.

The patent continuously accumulates overcurrent detection signals across multiple PWM periods rather than relying on single-period detection. The counter continuously increments when overcurrent is detected and only resets when the accumulated count reaches a predetermined threshold or when a reset condition is met. This continuous accumulation approach ensures reliable detection even when PWM duty ratio is small, as it integrates detection opportunities across multiple cycles, thereby maintaining both protection reliability and detection precision.

The patent employs periodic sampling of overcurrent conditions synchronized with PWM cycles, accumulating detection signals over multiple periods. Rather than using a continuous mask time interval that delays response, the system periodically evaluates accumulated detection counts at defined intervals (when the counter reaches a threshold or after a set number of PWM periods). This periodic evaluation mechanism maintains detection accuracy by filtering transient noise while minimizing response time delay, as protection is triggered as soon as the accumulation threshold is met rather than waiting for an arbitrary mask period to elapse.