Patent ID: 7728540
Filing Date: 2010-06-01
Classification: H02P

Abstract:
1. A motor driving circuit that receives an error signal having a digital value corresponding to a deviation between a current rotation speed of a motor, which is a subject to be driven, and its target value, so as to drive the motor, comprising: a digital filter that eliminates a high-frequency component of the error signal; a driving unit that controls an electric current flowing through the motor in accordance with the digital value of the error signal from which the high-frequency component is eliminated by the digital filter; and an upper-limit value setting unit that sets an upper limit value to the digital value of the error signal input to the digital filter, and wherein the upper-limit value setting unit is configured to change the upper limit value according to a setting signal from the outside and wherein the error signal comprises m bits, where m is a natural number; and the upper-limit value setting unit invalidates the high-order n bits, where n is a natural number satisfying n<m, of the digital value of the error signal.