Abstract: A method for controlling the current applied to a voice coil motor (VCM) prevents overheating of a coil in the VCM. The method includes the steps of defining an acceleration interval for measuring the distance traveled by a head moved by the VCM. The method also defines a distance traveled during the acceleration interval which can be used as a reference for indicating that the coil is being overheated. The VCM is driven for the acceleration interval and the distance traveled during the interval is measured and compared to the reference distance. If the difference exceeds a threshold, then the current being applied to the coil is controlled to maintain the coil temperature within a limit. If, however, the difference does not exceed the threshold, the current being applied to the coil is controlled to meet a performance requirement.

Abstract: Disclosed is a method in a disk drive that allows the functionality of a single high-resolution DAC to be replicated with a pair of lower-resolution DACs that are operated in a unique manner that provides monotonic behavior and reduces both differential and integral non-linearity. The two lower-resolution DACs take up substantially less space that one higher-resolution DAC when implemented in a semiconductor die. The method combines coarse values from one DAC with fine values from the other DAC to form a combined analog output signal within operational segments that collectively span a range of N-bit demands. The method operates such the operational segments overlap one another by 50 percent, with an endpoint of each operational segment ending near a center of an overlapped operational segment.