A/D AND D/A CONVERSION CIRCUIT

PROBLEM TO BE SOLVED: To accelerate A/D conversion without depending on the performance of an MPU by comparing a raw digital signal with an A/D conversion value in a data table and outputting an address where their contents coincide as a digital value. SOLUTION: An A/D converting part 1 converts an analog signal S2 into a raw digital value S3. An MPU 4 calculates a data table with the value S3 converted by the part 1 at that time by inputting a test command S1 accompanying a switch operation, etc., from a user to the MPU 4 and stores the data table in a memory 3. Then, a comparator circuit 2 compares the value S3 with the data table stored in the memory 3 when normal A/D conversion (other than test command) is performed and outputs a digital value S4. Then, the MPU 4 does not have to execute scaling processing of A/D conversion any more, and the acceleration of the scaling processing of the A/D conversion can be realized without depending on the performance of the MPU 4.