| 摘要 |
PURPOSE:To obtain highly accurate digital conversion value by determining error of an A/D converter at relevant temperature and compensating it basing on the digital conversion value and theoretical digital conversion value of analog reference voltage. CONSTITUTION:The reference voltage V for compensation obtained by dividing the reference voltage V by resistors R1, R2 is inputted to the terminal (a) of a selector and sensor output voltage Vb obtained by dividing the voltage V by resistance of a resistor R3 and a temperature sensor in inputted to the terminal (b) of the selector 3. A switchover control signal SL from an arithmetic unit 5 is made to 1 and voltage Va is inputted to an A/D convertor 4, and the digital value D2 at any temperature (t) is stored in a storage section 50. Next, the signal SL is made to 0, and voltage Vb is inputted to the convertor 4 and its digital value D3 is stored in the storage section 50. Then, difference S between theoretical digital conversion value D1 and D2 is determined by the unit 5. A highly accurate digital conversion value for which temperature error of the convertor 4 at temperature (t) is being compensated is obtained by operating D3+ S. |
