Abstract: A current driver is coupled to an inductor; a digital control for regulation of the current driver turns the current driver on or off coupled to the current driver; a comparator output coupled to the input of the digital control for regulation of the driver with inputs to compare a voltage of the inductor to a target voltage, a digital control for selection of one of a set of peaks and valleys of allowable current levels of the current driver, the digital control for selection of one of a set of peaks and valleys coupled to the output of the comparator and an input of the current driver, the digital control for the peak/valley current to monitor the duration of each high and low output state of the comparator output to determine the selection of one of the set of peak and valley of allowable current levels for the current driver.

Abstract: A current driver is coupled to an inductor; a digital control for regulation of the current driver turns the current driver on or off coupled to the current driver; a comparator output coupled to the input of the digital control for regulation of the driver with inputs to compare a voltage of the inductor to a target voltage, a digital control for selection of one of a set of peaks and valleys of allowable current levels of the current driver, the digital control for selection of one of a set of peaks and valleys coupled to the output of the comparator and an input of the current driver, the digital control for the peak/valley current to monitor the duration of each high and low output state of the comparator output to determine the selection of one of the set of peak and valley of allowable current levels for the current driver.

Abstract: A disk drive system including retract logic for control of the voice coil motor in a retract operation, in which the voice coil motor positions the read/write head actuator arm in a safe place in a loss-of-power event, is disclosed. The retract logic includes circuitry for controlling the application of power to the voice coil motor from an external capacitor in a pulse-width modulated manner. Current from the capacitor is coupled to the voice coil motor in a drive phase of the pulse-width modulation cycle, and is recirculated through the voice coil motor in a complementary phase of the pulse-width modulation cycle. The recirculation is accomplished by a recirculation transistor that is smaller than the pull-down transistor used in the drive phase.

Abstract: A disk drive system including retract logic for control of the voice coil motor in a retract operation, in which the voice coil motor positions the read/write head actuator arm in a safe place in a loss-of-power event, is disclosed. The retract logic includes circuitry for controlling the application of power to the voice coil motor from an external capacitor in a pulse-width modulated manner. Current from the capacitor is coupled to the voice coil motor in a drive phase of the pulse-width modulation cycle, and is recirculated through the voice coil motor in a complementary phase of the pulse-width modulation cycle. The recirculation is accomplished by a recirculation transistor that is smaller than the pull-down transistor used in the drive phase.