Power supply voltage monitoring circuit, sensor circuit for vehicle, and power steering apparatus

A sensor circuit for a vehicle, comprising:

• a sensor configured to sense a state of operation of the vehicle;
• a first microcomputer including a first microprocessor and a first interface, wherein the first microcomputer is connected to a ground, and configured to control the sensor;
• a second microcomputer including a second microprocessor and a second interface, wherein the second microcomputer is connected to the ground, and configured to control the sensor;
• a first power supply configured to supply electric power to the first microcomputer;
• a second power supply configured to supply electric power to the second microcomputer;
• a first reference voltage generation circuit connected between the first power supply and the first microcomputer, and configured to supply a first reference voltage to the first microcomputer in response to a condition that voltage of the first power supply is higher than the first reference voltage;
• and
• a first monitoring circuit connected between the second power supply and the first microcomputer, and configured to supply a first monitoring voltage to the first microcomputer, wherein the first microcomputer is configured to monitor voltage of the second power supply based on the supplied first monitoring voltage;
• wherein the first microcomputer includes a first voltage abnormality determination part configured to perform a first operation based on the supplied first reference voltage and the supplied first monitoring voltage, wherein the first operation includes detecting abnormality in the voltage of the first power supply and the voltage of the second power supply, and determining which one of the voltage of the first power supply and the voltage of the second power supply is abnormal.

A power steering apparatus comprising:

• a steering mechanism configured to steer a steered wheel in accordance with steering operation of a steering wheel;
• an electric motor configured to apply a steering force to the steering mechanism;
• a sensor configured to sense a state of steering of the steering mechanism;
• a motor control circuit configured to control drive of the electric motor based on the sensed state of steering of the steering mechanism;
• a first microcomputer including a first microprocessor and a first interface, wherein the first microcomputer is connected to a ground, and configured to control the sensor;
• a second microcomputer including a second microprocessor and a second interface, wherein the second microcomputer is connected to the ground, and configured to control the sensor;
• a first power supply configured to supply electric power to the first microcomputer;
• a second power supply configured to supply electric power to the second microcomputer;
• a first reference voltage generation circuit connected between the first power supply and the first microcomputer, and configured to supply a first reference voltage to the first microcomputer in response to a condition that voltage of the first power supply is higher than the first reference voltage;
• and
• a first monitoring circuit connected between the second power supply and the first microcomputer, and configured to supply a first monitoring voltage to the first microcomputer, wherein the first microcomputer is configured to monitor voltage of the second power supply based on the supplied first monitoring voltage;
• wherein the first microcomputer includes a first voltage abnormality determination part configured to perform a first operation based on the supplied first reference voltage and the supplied first monitoring voltage, wherein the first operation includes detecting abnormality in the voltage of the first power supply and the voltage of the second power supply, and determining which one of the voltage of the first power supply and the voltage of the second power supply is abnormal.