Patent ID: 8281167

Claim:
An electronic control apparatus for vehicles, comprising a main microcomputer which is activated when a given activation condition is met; a sub-microcomputer to which power supply voltage is supplied based on a power control signal controlling power supply to the sub-microcomputer, the power control signal being outputted by the main microcomputer; a first power supply unit that supplies, via a first supply line, power supply voltage to the main microcomputer to activate the main microcomputer; and a second power supply unit that supplies, via a second supply line different from the first supply line, power supply voltage to the sub-microcomputer to activate the sub-microcomputer, when the second power supply unit receives the power control signal from the main microcomputer, wherein the main microcomputer includes determining means for determining whether or not the sub-microcomputer should be made to operate and switching means for performing a switchover between output and non-output of the power control signal to the second power supply unit based on results of the determining means whereby the power supply to the sub-microcomputer is controlled; the first power supply unit includes means for receiving a further power control signal controlling power supply to the main microcomputer and means for switching an operation mode of an operating power supply voltage to the main microcomputer from a low-power output mode enabling a small amount of power to be outputted to a high-power output mode enabling a high amount of power to be outputted higher than the small amount of power; and the main microcomputer includes means for operating in a waiting mode with power consumed less than in a normal operation mode of the main microcomputer, depending on the operating power supply voltage from the first power supply unit operating in the low-power output mode, until the determining means determines that an activation condition has been met, and means for outputting the further power control signal to the first power supply unit when it is determined that the activation condition has been met in the waiting mode, allowing the first power supply unit to transit from the waiting mode the normal operation mode.