Zero-crossing detection circuit and commutation device using the zero-crossing detection circuit

Abstract

A zero-crossing detection circuit and a commutation device using the zero-crossing detection circuit are provided. The zero-crossing detection circuit is adapted into a three-phase brushless DC (direct current) motor with first to third coils. One terminal of each of the first to third coils is electrically coupled together with each other. The detection circuit comprises a first selection circuit, a second selection circuit and a comparator. The first selection circuit and the second selection circuit are both electrically coupled to another terminals of the first to third coils, to obtain first to third terminal voltages, and output one of the first to third terminal voltages according to a selection signal. The comparator is configured for comparing an output of the first selection circuit and an output of the second selection circuit, to output a comparing result.