| 摘要 |
PROBLEM TO BE SOLVED: To provide an A/D converter capable of selecting a voltage pre-charged to a sampling capacitor, according to the type of input voltage by each input terminal. SOLUTION: A microcomputer includes an input terminal selection circuit 13 for selecting one among a plurality of analog input terminals 12; preset registers 15, whose number is equal to the number of the input terminals 12; a preset value object storage register 16 for storing a plurality of preset value objects; and a preset value selection circuit 17 for selecting one of the preset value objects and storing the selected object to the preset register 15. A pre-charge voltage is obtained, by applying D/A conversion to the preset value stored in the preset register 15, corresponding to the input terminal selected by the input terminal selection circuit 13. One preset value object is selected according to the kind of the input voltage at each input terminal and the precharge voltage is precharged to the sampling capacitor C for a precharge period in a sampling period of A/D conversion. COPYRIGHT: (C)2005,JPO&NCIPI
|
