Patent ID: 8653782

Claim:
A motor driving device for driving a motor, comprising: a driving switching element that is connected in series with the motor between a power source and a ground, and is operated by a pulse width modulation signal to drive the motor; a return current path forming unit that is connected in parallel with the motor and provides a current path to allow a return current when the driving switching element is turned off; a series circuit that includes a current flow restriction element and a switch connected in series with the current flow restriction element, the series circuit being connected in parallel with the return current path forming unit; a control circuit that provides the pulse width modulation signal to a control terminal of the driving switching element; and a disconnection determination unit that prohibits the control circuit from outputting the pulse width modulation signal and closes the switch of the series circuit when it is determined that a voltage without having fluctuation according to the pulse width modulation signal is applied to the motor as a result of comparing a voltage detected at a common connecting point between the motor and the driving switching element with a first threshold, and determines a disconnection of the motor on condition that the voltage detected in a state where output of the pulse width modulation signal is prohibited and the switch of the series circuit is closed indicates a change across a second threshold.