Patent Number: 6,169,944

Title: Microcomputer-built-in, on-vehicle electric unit

Abstract: An on-vehicle electric unit has a microcomputer formed of a RAM which stores information indicating an operating condition of the on-vehicle electric unit and momentary-power-supply-interruption check information, a ROM which stores an operation program of the microcomputer, an initial value for the information indicating the operating condition, and the momentary-power-supply-interruption check information, and a CPU which controls the on-vehicle electric unit according to the information indicating the operating condition and the operation program, and a reset circuit which resets the microcomputer if a voltage of the on-vehicle power supply is reduced. The microcomputer checks whether the momentary-power-supply-interruption check information stored in the RAM remains when it is reset. When the momentary-power-supply-interruption check information is detected, the microcomputer determines that a momentary interruption of the on-vehicle power supply has occurred and restarts controlling the on-vehicle electric unit. If the momentary-power-supply-interruption check information is not detected, the microcomputer determines that not a momentary interruption of the on-vehicle power supply but a voltage drop lasting for a time period exceeding that of a momentary interruption has occurred, initializes the RAM, and then restarts controlling the on-vehicle electric unit.

Inventors: Hayasaka; Satoshi (Miyagi-ken, JP)

Assignee: Alps Electric Co., Ltd.

International Classification: G06F 11/14 (20060101); G06F 019/00 ()

Expiration Date: 01/02/2018