US 12,244,252 B2
Motor driver circuit for linear motor, positioning device using the same, and hard disk device
Hisashi Sugie, Kyoto (JP)
Assigned to ROHM CO., LTD., Kyoto (JP)
Filed by ROHM CO., LTD., Kyoto (JP)
Filed on Nov. 15, 2022, as Appl. No. 17/987,192.
Claims priority of application No. 2021-189194 (JP), filed on Nov. 22, 2021.
Prior Publication US 2023/0163708 A1, May 25, 2023
Int. Cl. H02P 25/06 (2016.01); G11B 5/55 (2006.01); H02P 23/14 (2006.01)
CPC H02P 23/14 (2013.01) [G11B 5/5521 (2013.01); H02P 25/06 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A motor driver circuit comprising:
a current detection circuit configured to generate a current detection signal according to a drive current of a motor as an object to be driven;
a first amplifier configured to amplify the current detection signal;
a second amplifier configured to multiply a voltage across the motor by a gain smaller than 1 and output the multiplied voltage;
a third amplifier configured to generate a back electromotive force detection signal according to a difference between an output of the first amplifier and an output of the second amplifier; and
a calibration circuit configured to adjust a gain of the first amplifier such that the output of the first amplifier and the output of the second amplifier have a same voltage in a calibration mode where the motor does not move.