| 摘要 |
PROBLEM TO BE SOLVED: To provide an A/D converter which offers a wider input dynamic range combined with an enhanced minimum resolution without requiring complicated external control, and in addition allows measurement to be performed in less time, illuminance sensor using the same, illumination device and electronic device. SOLUTION: The A/D converter according to the present invention has a capacitor C1 storing an electric charge commensurate with an input current, and discharge circuits 12 and 13 that discharge the electric charge stored in the capacitor C1. While the capacitor C1 is charged for a predetermined charge period, every time a predetermined amount of electric charge is stored in the capacitor C1, the electric charge stored there is discharged by the discharge circuit 12. After the charge period, the electric charge is discharged by the discharge circuit 13. Thus, based on the number of discharges performed by the discharge circuit 12 and the discharge duration of the discharge circuit 13, a digital value (DOUT) of the voltage commensurate with the amount of electric charge with which the capacitor C1 has been charged is outputted. COPYRIGHT: (C)2008,JPO&INPIT |
