Power supply control system and method of controlling power supply

#The present application is based on and claims priority to Japanese Patent Application No. 2007-249463 filed on Sep. 26, 2007, the contents of which are incorporated in their entirety herein by reference.

#1. Field of the Invention

#The present invention relates to a power supply control system and a method controlling a power supply.

#Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of preferred embodiments when taken together with the accompanying drawings. In the drawings:

#FIG. 1A is a block diagram illustrating a power supply control system according to an exemplary embodiment of the invention and FIG. 1B is a diagram illustrating an ignition switch;

#FIG. 2 is a block diagram illustrating an electronic control unit according to the exemplary embodiment;

#A power supply control system 200 according to an exemplary embodiment of the invention will be described with reference to FIG. 1A and FIG. 1B. The power supply control system 200 includes three electronic control units (ECUs) 1A, 1B, and 1C. Each of the ECUs 1A-1C controls an electronic device independently of the others of the ECUs 1A-1C. The ECUs 1A-1C are coupled with a monitoring device 1E through a communicating line 30. The monitoring device 1E is configured to monitor a power-receiving state of each of the ECUs 1A-1C. An operating voltage is supplied to the ECUs 1A-1C through a power source line 100. On the power source line 100, a power source switch 110 is provided. The power source switch 110 is configured to stop the supply of the operating voltage to all of the ECUs 1A-1C at a time. The ECUs 1A-1C are provided for controlling the electronic devices provided in a vehicle, for example. The power source line 100 receives a power source voltage (i.e., the operating voltage) from a battery B in the vehicle.

#Each of the ECUs 1A-1C and the monitoring device 1E includes a microcomputer. The communicating line 30 may be made of a serial communication bus such as a controller area network communication (CAN communication) and a local interconnect network communication (LIN communication), for example. At least a part of the communication line 30 may be made of a radio communication bus. The power source switch 110 may be configured as a relay switch including a single pole single throw switch (SPST switch) 111 and a solenoid 112, for example. The SPST switch 111 is a mechanical contact type and the solenoid 112 drives the SPST switch 111. The power source switch 110 may also be configured as a semiconductor switch using a transistor or a thyristor.

#The ECUs 1A-1C coupled with the power source line 100 are divided into a plurality of power source systems. A selector switch is provided for selecting a power-receiving state of each of the ECUs 1A-1C that receives the operating voltage from the power source line 100. For example, the selector switch is provided by an ignition switch 50. As shown in FIG. 1B, the ignition switch 50 is set at an IG-OFF position, an ACC-ON position or an IG-ON position. When the ignition switch 50 is set at the IG-OFF position, an engine and accessories including a car audio system, a car navigation device, and power windows are deenergized. When the ignition switch 50 is set at the ACC-ON position, the accessories are energized and the engine is deenergized. When the ignition switch 50 is set at the IG-ON position, the engine and the accessories are energized. The selected position of the ignition switch 50 is monitored by an ignition monitoring part 1G coupled with the communicating line 30, Each of the monitoring device 1E and the ECUs 1A-1C receives a signal in accordance with the monitored result from the ignition monitoring part 1G through the communicating line 30.