Motor Driving Device

A motor driving device, which drives a three-phase motor having coils with a U phase, a V phase and a W phase by a two-phase modulation, comprising:

• a control signal generator, identifying a position of a rotor based on a position detection signal of the rotor of the three-phase motor, and outputting a digital control signal according to the position;
• a DA converter, including a resistance ladder having a series circuit of a plurality of resistors, wherein the resistance ladder is used to, based on the control signal, generate analog first and second command phase voltages that represent phase voltages to be supplied to the coils of two of the U, V and W phases;
• a periodic voltage generator, generating an analog periodic voltage with a voltage value that fluctuates periodically;
• a first comparator, generating a first PWM signal by comparing the analog first command phase voltage and the analog periodic voltage;
• a second comparator, generating a second PWM signal by comparing the analog second command phase voltage and the analog periodic voltage;
• and
• a logic circuit, implementing the two-phase modulation by assigning the first and second PWM signals to any two of the U, V and W phases based on the position detection signal.