Relay driving apparatus and method having relay contact turn-on holding function

摘要

A relay driving apparatus has a control circuit, which supplies a first voltage to a relay coil in response to a relay driving signal to turn on a relay contact, and thereafter a second voltage lower than the first voltage to the relay coil to keep an ON state of the relay contact. The apparatus also has a detection circuit, which is connected in a coil current supply path and detects a state change of the relay contact to an OFF state from the ON state based on a current change in the coil current. The control circuit supplies the first voltage again to the relay coil in response to the state change detected by the detection circuit to restore the ON state.