WATCHDOG CIRCUIT OF ELECTRONIC CONTROL UNIT FOR VEHICLE

摘要

PURPOSE: A watchdog circuit of an electronic control unit for a vehicle is provided to output an alarm signal and scan pulse for a watchdog timer at the same output port, thereby reducing the number of the output ports of the control unit. CONSTITUTION: In an electronic control unit having a watchdog timer(30) and a light-emitting unit(50) for alarming the abnormal condition of a vehicle, a watchdog circuit is composed of a control unit(10) for outputting scan pulses and alarm signals at the same output port, a filter(20) for allowing the alarm signals to pass through the filter, and a switching element(40) connected to an output end of the filter and driving the light emitting unit(50). The filter(20) is connected to the output port with the watchdog timer(30).