Semiconductor integrated circuit and operating method for the same

摘要

The present invention realizes a calibration operation for detecting a motor speed, without employing digital correcting by an external CPU. The calibration operation calculates a comparison reference value corresponding to aback EMF detection signal of a back EMF detector circuit when a zero current flows through a motor and when an arm is fixed. Accordingly, the back EMF detection signal of the back EMF detector circuit is set as the first value and the second value responding to the non-zero current flowing through the motor, and the semiconductor integrated circuit calculates the comparison reference value from the first value and the second value. The difference between the comparison reference value and the comparison input value as the back EMF detection signal of the back EMF detector circuit is reduced by adjusting the gain of an internal amplifier of the back EMF detector circuit by an adjustment unit.

主权项

1. A semiconductor integrated circuit to be mounted in a motor drive controller for driving a motor to move a magnetic head of a hard disk drive unit, the semiconductor integrated circuit being operable to make flow a non-zero current which is substantially not a zero current through the motor, in a calibration operation for a loading operation which moves the magnetic head from a ramp mechanism to a surface of a disk medium or an unloading operation which moves the magnetic head from the surface of the disk medium to the ramp mechanism,
wherein the non-zero current presses an arm mounting the magnetic head against an outer circumference stopper at the time of the calibration operation for the loading operation or presses the arm mounting the magnetic head against an inner circumference stopper at the time of the calibration operation for the unloading operation, so as to bring the arm into a fixed state, wherein the semiconductor integrated circuit comprises: a motor driver circuit operable to drive the motor; a back EMF (electromotive force) detector circuit operable to detect a back electromotive force generated in the motor; and an adjustment unit operable to adjust the gain of an internal amplifier of the back EMF detector circuit, wherein, at the time of the calibration operation, a back EMF (electromotive force) detection signal is generated from the back EMF detector circuit, in response to the motor driver circuit making the non-zero current flow through the motor, wherein the semiconductor integrated circuit generates a comparison reference value corresponding to the back EMF detection signal generated from the back EMF detector circuit, in the fixed state of the arm and the state where a zero current substantially with a zero current value flows through the motor by the calibration operation, wherein, at the time of the calibration operation, the semiconductor integrated circuit sets the back EMF detection signal generated from the back EMF detector circuit as a first value and a second value, in response to the non-zero current flowing through the motor, wherein, at the time of the calibration operation, the semiconductor integrated circuit calculates the comparison reference value from the back EMF detection signal as the first value and the back EMF detection signal as the second value, wherein the adjustment unit of the semiconductor integrated circuit adjusts the gain of the internal amplifier of the back EMF detector circuit by the calibration operation, and the back EMF detector circuit to which the adjusted gain is reflected generates the back EMF detection signal as a comparison input value, and wherein the adjustment unit of the semiconductor integrated circuit adjusts the gain of the internal amplifier of the back EMF detector circuit so as to reduce the difference of the comparison input value and the comparison reference value by the calibration operation.