The A8902CLBA is a three-phase brushless dc motor controller/ driver for use in 5 V or 12 V hard-disk drives. The three half-bridge outputs are low on-resistance n-channel DMOS devices capable of driving up to 1.25 A. The A8902CLBA provides complete, reliable, self-contained back-EMF sensing motor startup and running algorithms. A programmable digital frequency-locked loop speed control circuit together with the linear current control circuitry provides precise motor speed regulation.