Abstract: A disk drive system that functions at various different power supply voltage levels includes a reset generator for resetting the disk drive in response to a predetermined reset condition dependent upon a drop in the power supply voltage. An adapter circuit coupled to the reset generator produces the reset condition by applying a multiplier to the supply potential of the system to establish a predetermined voltage at a reset node. The adapter circuit includes a switch for selecting the multiplier based upon the particular mode of operation desired. The mode of operation is selected based upon an expected operating range of the power supply potential. A logic device is coupled to the adapter circuit to determine the particular mode of operation and for monitoring the current operating supply potential. The logic device is coupled to the switch to change the multiplier in accordance with the particular mode of operation selected, as the supply potential varies through an expected operating range.

Abstract: A disk drive system that functions at various different power supply voltage levels includes a reset generator for resetting the disk drive in response to a predetermined reset condition dependent upon a drop in the power supply voltage. An adapter circuit coupled to the reset generator produces the reset condition by applying a multiplier to the supply potential of the system to establish a predetermined voltage at a reset node. The adapter circuit includes a switching means for selecting the multiplier based upon the particular mode of operation desired. The mode of operation is selected based upon an expected operating range of the power supply potential. A logic device is coupled to the adapter circuit to determine the particular mode of operation and for monitoring the current operating supply potential.

Abstract: A control system employing a sample and early-off hold function implements the hold function in such a way as to effectively create a filter function. Instead of holding a constant value for the duration of a sample period, the control system turns the held sample value on and off multiple times during the sampling period. The notch filter is tunable by adjustment of the number, time and duration of the held sample intervals.

Abstract: An apparatus and method for torque disturbance precompensation in a disk drive spindle motor includes an amplifier for providing current to the spindle motor in response to an input signal. A velocity detector determines the velocity of the motor, which is then compared to a predetermined velocity to generate an error signal. Compensator elements of the control loop develop an actuating signal from the error signal. The actuating signal is then summed with a torque correction value provided by a look-up table. The torque correction value precompensates the motor by causing the amplifier to provide an additional incremented current to the motor. The additional current corrects the torque disturbance resulting from the movement of the heads across the disk.

Abstract: In the disk drive system of the present invention, the peak power drain on the power supply is maintained within acceptable levels while improving the seek performance of the actuator. This is achieved by timely decreasing the current to the spindle motor during at least a portion of the accelerate and decelerate portions of the seek, to provide the additional current necessary to accelerate faster and therefore improve the seek time performance. The current taken away from the spindle motor during those times is returned to the spindle motor during the coast portion of the seek in order that spindle velocity within tolerances is maintained by the end of the seek when a read/write operation occurs. Thus, the seek performance is improved and the peak power as seen at the power supply is maintained constant or reduced.