Patent ID: 7352144

Claim:
A motor driving device comprising a plurality of series circuits formed by connecting two MOSFETs in series between positive and negative terminals of a direct-current power source, with connection point of the two MOSFETs connected to a driving coil of the motor, wherein the MOSFET is composed of an FET main body, and a parasitic element group, wherein the parasitic element group is composed of: a transistor connected in parallel to the FET main body; a zener diode connected between collector and base of the transistor; a capacitor connected in parallel to the zener diode; and a resistor connected between base and emitter of the transistor, and wherein defining a current flowing in the FET main body when the MOSFET is turned on as a first current, and a current flowing in the parasitic element group upon transition of the MOSFET from on to off state as a second current, the MOSFET has a current tolerance in a sum of maximum value of the first current and maximum value of the second current.