| 摘要 |
PROBLEM TO BE SOLVED: To provide an analog-digital conversion circuit in which the minimum resolution smaller than the conventional one can be set as the minimum resolution without spoiling measurement accuracy, and also to provide an illuminance sensor, a proximity sensor, a cellular phone, and a digital camera. SOLUTION: The analog-digital conversion circuit is provided with: a charging circuit 2 which has capacity C1 for accumulating charges according to input current; a discharging circuit 6 which discharges the charges accumulated by the capacity C1; a comparator circuit 3 which compares output voltage of the charging circuit 2 with reference voltage Vref to be output by a voltage source V1; a switch SW1 which opens and closes between output of the voltage source V1 and output of the charging circuit 2; a switch control circuit 7 which outputs a switch control signal for controlling opening and closing of the switch SW1 to the switch SW1; a control circuit 4 which outputs a digital value according to discharge frequencies from a comparison signal comp to be output from the comparator circuit 3; and a PWM control circuit 5 which makes pulse width modulation control of a discharged charge amount of the discharging circuit 6. COPYRIGHT: (C)2011,JPO&INPIT
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