Patent ID: 8089231

Claim:
A PWM control circuit for generating a PWM signal for use in controlling a control target device, comprising: a multiplier configured to multiply a signal value of a changing signal whose level is changing over time, and a control value which is set arbitrarily in a predetermined range, to thereby obtain a multiplication value, the changing signal being a sinusoidal wave signal outputted from a sensor installed in the control target device; a PWM signal generation circuit for generating a PWM signal having a pulse width corresponding to the multiplication value by executing PWM on the multiplication value; and a digital decoder for digitizing the sinusoidal wave signal outputted from the sensor installed in the control target device to thereby generate the changing signal value and to generate a positive/negative sign signal indicating either an upper half or a lower half of the sinusoidal wave signal, wherein the digital decoder is selectively operable in either of: (i) a first operation mode in which the digital decoder generates the changing signal value to indicate a change of the sinusoidal wave signal that changes in analog fashion; and (ii) a second operation mode in which the digital decoder generates the changing signal value to have a constant value irrespective of the change of the sinusoidal wave signal that changes in analog fashion.