Patent ID: 6927711

Claim:
A sensor apparatus comprising: a constant-voltage circuit for stabilizing a power supply voltage applied directly thereto through a power supply terminal to produce a constant voltage; an oscillation circuit for outputting an oscillation frequency on the basis of the applied voltage; a switch circuit for setting a first switching condition for applying said constant voltage from said constant-voltage circuit to said oscillation circuit and a second switching condition for applying said power supply voltage from said power supply terminal directly to said oscillation circuit; and an A/D conversion circuit made to operate in a state where said constant voltage from said constant-voltage circuit is used as a drive voltage therefor, and made to carry out sampling processing on analog data on the basis of said oscillation frequency inputted from said oscillation circuit to produce and output digital data, wherein said switch circuit is placed into said first switching condition when at least said A/D conversion circuit produces and outputs said digital data.