| 摘要 |
PROBLEM TO BE SOLVED: To detect a component defect and to secure operation margin as a device, while a defect of a bus can be detected in a short time.SOLUTION: When a voltage monitoring part 1 compares input voltage with threshold voltage, and if the input voltage is out of the range of the threshold voltage, the voltage monitoring part 1 outputs an error signal. A switching circuit 5 switches the voltage to be input in the voltage monitoring part 1 between monitoring voltage from power supply circuits 2-1, 2-2,..., 2-n and output voltage of bus devices 21-1, 21-2, ..., 21-n. When monitoring the bus, the switching circuit 5 is switched to an output voltage side of the device of the bus and threshold setting registers 11-1, 11-2, ..., 11-n are set to the voltage equivalent to a logical level of the bus in the normal range. When power supply is monitored, the threshold setting registers 11-1, 11-2, ..., 11-n are set to the voltage of the power supply circuit in the normal range, while a switching part is switched to a monitoring voltage side of the power supply circuit. |
