| 摘要 |
PURPOSE:To discharge completely an integration capacitor at resetting by limiting a charge quantity to the integration capacitor to a prescribed value or below through the operation of a switching element after the end of A/D conversion. CONSTITUTION:Even when the A/D conversion of both dual integration system A/D conversion circuits AD1, AD2 is finished and a reset signal Q3 is outputted, the positive charging to an integration capacitor C2 is continued based on a constant current ir by a constant current circuit CI2. When the charging voltage of the integration capacitor C2 is equal to a forward voltage VF of a diode D2, the further charging to the integration capacitor C2 is stopped and an output VINT2 of an integration circuit INT2 is kept to the same voltage as the forward voltage VF of the diode D2 and The charing electric charge in the integration capacitor C2 is decreased considerably.
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