| 摘要 |
<p>PURPOSE:To improve productivity and detection accuracy by providing an operation circuit for obtaining an air fluid temperature voltage and an output circuit for making proper the range where A/D conversion is possible. CONSTITUTION:A power transistor 61 is controlled so that an output voltage V4 of an operational amplifier 90 of a control circuit 1 reaches a level so that voltages V1 and V2 are equal an a sensor 580 is used for measuring temperature. A first output circuit 2 is provided with a voltage amplification operation and efficiently uses a range where A/D conversion can be made by an A/D converter, thus. reducing the bit error on A/D conversion. An operation circuit 3 amplifies voltages V1 and V3 from Wheatstone bridge circuit and a circuit 1 as V3/V1. When the resistance of resistors 93 and 94 are set to R1 and R2, respectively, the output V6 of the circuit 3 is obtained by V6 (R2/R1)X(V3/V1). A second output circuit 4 also has a voltage amplification operation and efficiently uses the A/D conversion range of the A/D converter for the range where A/D conversion can be made, thus reducing the bit error on A/D conversion.</p> |
