Power circuit of a vehicular electronic control unit

摘要

A power circuit of a vehicular electronic control unit is provided with a constant voltage power circuit, an awakening timer circuit, and first and second power supply circuits each of which is supplied with power from a vehicle battery. The constant voltage power circuit is supplied with power from the vehicle battery via the first and second power supply circuits. The awakening timer circuit generates an awakening trigger signal upon a lapse of a prescribed time from a stop of power supply to the microprocessor. The first power supply circuit has an output contact as a first opening/closing element and a coil for closing the output contact. The second power supply circuit has a second opening/closing element that is provided between the vehicle battery and the constant voltage power circuit and is closed at least in response to the awakening trigger signal.