A full-wave motor drive IC based on the back-EMF sensing principle

A bipolar IC has been designed which allows full-wave driving of brushless three-phase DC motors. The three push-pull power stages operate in a switching mode. The commutation moments are directly derived from the zero-crossings of the back-EMF (electromotive force) in the floating motor windings. A start-up system will generate communications when no zero-crossing can be detected. A highly accurate tach-signal is defined by the EMF zero-crossings. This IC offers the possibility of accurate full-wave motor-driving without extra sensors in the motor.<>