Patent ID: 7183734

Claim:
An integrated circuit particularly configured for control of a two-phase brushless DC motor having a rotor with permanent magnet poles and a stator with two sets of stator coils coupled to a drive circuit, end with the drive circuit in switching relation to the sets of stator coils to alternately energize the respective sets, of stator coils, the two sets of stator coils connected in common to a motor supply voltage and connected through separate switches of the drive circuit to ground, the integrated circuit comprising: EMF circuitry coupled to receive and sample an electromotive force (EMF) signal corresponding to an EMF voltage generated in response to rotor motion upon whichever set of stator coils as not energized at any given sampling time, the EMF circuitry having a voltage divider resistance network connected across the two sets of stator coils to provide a measure of EMF voltage relative to the motor supply voltage of whichever set of stator coils is not energized, with the energized set of stator coils serving as a ground reference through a conducting switch of the drive circuit; and commutation control circuitry responsive to the sampled EMF signal to provide switching control signals to the drive circuit, such that commutation times are determined by the EMF voltage on the non-energized stator coils.