| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time required for outputting detection results by a pressure sensor. SOLUTION: The pressure sensor circuit comprises the pressure sensor 1 for generating detection signals of an analog quantity corresponding to a physical quantity to be detected and an integrating type A/D conversion circuit 11 for A/D converting the detection signals. The A/D conversion circuit 11 is constituted of resistors R1 and R2, switches SW1 and SW2, operational amplifiers OP1 and OP2, a capacitor C1, a clock 111 and a control logic 112. The control logic 112 controls the whole of the A/D conversion circuit 11, turning on the switch SW1 and turning off the switch SW2 from a starting time point of an input integration time to a time point after a predetermined time passes, and turning off the switch S1 and turning on the switch SW2 from the time point when the predetermined time passes to a time point when the comparison result that an output level of the operation amplifier OP1 crosses an AGND level can be obtained at the operational amplifier OP2. Moreover, the control logic controls to output a predetermined pulse train as an output of this pressure sensor circuit.
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