Patent ID: 8593100

Claim:
A motor drive circuit configured to drive a motor coil based on duty ratio of a PWM signal, comprising: a first pulse signal generating circuit configured to generate a first pulse signal for each time period, the time period being equal to 1/n of a time period during which the PWM signal is at one logic level, wherein n is a natural number greater than zero; a counter configured to change a count value based on the first pulse signal; a drive signal output circuit configured to output a drive signal of one logic level when the count value is not a predetermined value, and output the drive signal of the other logic level when the count value reaches the predetermined value; a drive circuit configured to perform PWM driving for the motor coil based on the duty ratio of the drive signal; and a setting circuit configured to set, in the counter, such a count value as to decrease a current passing through the motor coil, for each period of the PWM signal, in a time period during which the current passing through the motor coil is decreased, and set, in the counter, such a count value as to increase the current passing through the motor coil, for each period of the PWM signal, in a time period during which the current passing through the motor coil is increased, out of a time period during which the current passing through the motor coil is changed in direction.