Abstract: In a load-drive controller, a first comparing unit compares a load current supplied from an H bridge circuit and a desired setting current; a PWM control unit generates a control signal to control the load current; a gate driver drives and controls output transistors of the H bridge circuit based on the control signal, and a load current monitoring unit determines which is larger a level shift equivalent value of the setting current or a peak hold equivalent value of the load current, and the PWM control unit controls increase or decrease of the load current based on a comparison result of the first comparing unit and on a determination result of the load current monitoring unit, so that the load current quickly reaches the setting current of a micro step drive during decrease of the setting current.

Abstract: In a load-drive controller, a first comparing unit compares a load current supplied from an H bridge circuit and a desired setting current; a PWM control unit generates a control signal to control the load current; a gate driver drives and controls output transistors of the H bridge circuit based on the control signal, and a load current monitoring unit determines which is larger a level shift equivalent value of the setting current or a peak hold equivalent value of the load current, and the PWM control unit controls increase or decrease of the load current based on a comparison result of the first comparing unit and on a determination result of the load current monitoring unit, so that the load current quickly reaches the setting current of a micro step drive during decrease of the setting current.

Abstract: In a magnetic disk drive, overshoot caused in reversing the flowing direction of a recording current flowing through a magnetic head is intensified. The magnetic disk drive includes first and second differential pulse generation units for respectively generating first and second differential pulse signals by differentiating first and second recording signals; and first and second transistors that are provided in parallel to a resistor disposed between ground and an H bridge circuit for driving the magnetic head and are respectively turned on in accordance with the first and second differential pulse signals. When the flowing direction of the recording current is reversed in response to the first and second recording signals, one of the first and second differential pulse signals is generated, and hence, one of the first and second transistors is temporarily turned on. As a result, the overshoot of the recording current is intensified.