| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a physical quantity sensor capable of reliably detecting failures caused by a poor contact and the like at a connection part between the physical quantity sensor and a controller. SOLUTION: The physical quantity sensor comprises a physical quantity detecting circuit 21 electrically connected to the controller through a power line P, an output line O and a ground line G to output a sensor signal corresponding to a physical quantity. A power monitoring circuit 22 is provided for monitoring whether a supply voltageΔV between the power line P and the ground line G satisfies a reference voltage value or not, which outputs a sensor signal to the controller when the supply voltageΔV is higher than the reference voltage value and outputs a failure occurrence signal to the controller instead of the sensor signal when the supply voltageΔV is lower than the reference voltage value. The power monitoring circuit 22 comprises a constant voltage circuit 22c for outputting the reference voltage value, which is configured such that the reference voltage value becomes a constant voltage based upon an electric potential of the ground line G.</p> |
