Disk drive system which uses a common dac for digital positioning

Abstract

Provided is a disk drive with a disk and an actuator assembly on which a communication device is mounted for communication with the disk. Position information read from the disk is processed through a channel that generates an analog position error signal that is then converted to a digital position error signal by a first signal converter. Based on the digital position error signal, a controller determines whether realignment of the communication device with the disk is required. The operation of the first signal converter is only periodically required. When realignment is required, then a digital position control signal is generated by the controller and is then converted to an analog position control signal by a second signal converter, which shares circuitry with the first signal converter. Normally, the second signal converter is operating to realign the communication device. Therefore, the shared circuitry is normally operating as part of the second signal converter. Operation of the shared circuitry between the first signal converter and the second signal converter is switched by a switch controlled by the controller. Based on the analog position control signal, a servo system causes the actuator assembly to reposition the communication device for fine adjustment to maintain proper alignment with the disk.