The LM621 is a bipolar IC designed for commutation of brushless DC motors The part is compatible with both three- and four-phase motors It can directly drive the power switching devices used to drive the motor The LM621 provides an adjustable dead-time circuit to eliminate ``shootthrough'' current spiking in the power switching circuitry Operation is from a 5V supply but output swings of up to 40V are accommodated The part is packaged in an 18-pin dual-in-line package