The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 29, 2012
Filed:
Jan. 22, 2010
Tatsuro Shimizu, Kyoto, JP;
Tatsuro Shimizu, Kyoto, JP;
Rohm Co., Ltd., , JP;
Abstract
A motor drive circuit includes an H-bridge circuit, voltage difference detection circuit, calibration circuit, back electromotive voltage detection circuit, control circuit, and calibration value acquisition circuit. The H-bridge circuit is connected to a DC motor. The voltage difference detection circuit outputs terminal voltage according to voltage difference occurring between both terminals of the DC motor. The calibration circuit outputs calibration voltage according to the resistance component. The back electromotive voltage detection circuit outputs voltage according to the difference between the terminal voltage and the calibration voltage, as detection voltage indicating back electromotive voltage. The control circuit drives the H-bridge circuit by pulse width modulation. The calibration circuit calibrates voltage drop occurring at the ON resistance of the low-side transistor using a calibration value that corresponds to the ratio between the resistance component and the ON resistance of the low-side transistor, and outputs calibration voltage which corresponds to the resistance component.