Patent ID: 7675199

Claim:
A disconnection detecting circuit for detecting disconnection of a load connected to a pair of a first output terminal and a second output terminal of a load drive circuit for supplying an AC signal to the load, comprising: a capacitor; a diode connected in a chargeable direction between (i) the second output terminal, to which one end of the load is connected, and (ii) the capacitor; an initialization circuit for initializing charges in the capacitor; a determination circuit for outputting a disconnection detection signal when a voltage across terminals of the capacitor is lower than a predetermined determination reference voltage; and a control circuit, for executing disconnection detection, and for, when executing the disconnection detection, (i) electrically setting the second output terminal to a high-impedance state in the load drive circuit, (ii) operating the initialization circuit to initialize charges in the capacitor, making the load drive circuit operate, and (iii) driving the first output terminal, to which an opposite end of the load is connected, with an AC signal.