Title:
CIRCUIT FOR DRIVING STEPPER MOTOR, METHOD FOR DRIVING SAID STEPPER MOTOR, AND ELECTRONIC DEVICE IN WHICH SAID CIRCUIT IS USED
Document Type and Number:
WIPO Patent Application WO/2021/112125
Kind Code:
A1
Abstract:
A drive circuit 200 drives a stepper motor 102 in a two-phase excitation method in synchronization with an input clock CLK. A constant current chopper circuit 250 generates a pulse modulation signal SPWM so that a detected value for a coil current IOUT1 approaches a current setting value IREF. A detection window generation circuit 260 generates a detection window in which the start point is a time at which the coil current IOUT1 becomes smaller than a prescribed threshold value IZC. When the detection window is in an open state, a logic circuit 270 puts a full bridge circuit 202 in a high-impedance state, and when the detection window is in a closed state, the logic circuit 270 controls the full bridge circuit 202 in response to a pulse modulation signal SPWM. When the detection window is in an open state, a back electromotive force detection circuit 230 detects a back electromotive force VBEMF1 of a coil L1. A current value setting circuit 210 performs feedback control of the current setting value IREF on the basis of the back electromotive force VBEMF1.
Inventors:
HASHIMOTO HIROKI (JP)
TSUCHIHASHI MASANORI (JP)
OKADA MITSUO (JP)
TSUCHIHASHI MASANORI (JP)
OKADA MITSUO (JP)
Application Number:
PCT/JP2020/044858
Publication Date:
June 10, 2021
Filing Date:
December 02, 2020
Export Citation:
Assignee:
ROHM CO LTD (JP)
International Classes:
H02P8/16
Foreign References:
| JP2009065806A | 2009-03-26 | |||
| JP6258004B2 | 2018-01-10 | |||
| JP2007267553A | 2007-10-11 |
Attorney, Agent or Firm:
MORISHITA Sakaki (JP)
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