M16C/62 Group DATASHEET

A-D ConverterMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER(a) Sample and holdSample and hold is selected by setting bit 0 of the A-D control register 2 (address 03D416) to “1”. Whensample and hold is selected, the rate of conversion of each pin increases. As a result, a 28 fAD cycle isachieved with 8-bit resolution and 33 fAD with 10-bit resolution. Sample and hold can be selected in allmodes. However, in all modes, be sure to specify before starting A-D conversion whether sample andhold is to be used.(b) Extended analog input pinsIn one-shot mode and repeat mode, the input via the extended analog input pins ANEX0 and ANEX1 canalso be converted from analog to digital.When bit 6 of the A-D control register 1 (address 03D716) is “1” and bit 7 is “0”, input via ANEX0 isconverted from analog to digital. The result of conversion is stored in A-D register 0.When bit 6 of the A-D control register 1 (address 03D716) is “0” and bit 7 is “1”, input via ANEX1 isconverted from analog to digital. The result of conversion is stored in A-D register 1.(c) External operation amp connection modeIn this mode, multiple external analog inputs via the extended analog input pins, ANEX0 and ANEX1, canbe amplified together by just one operation amp and used as the input for A-D conversion.When bit 6 of the A-D control register 1 (address 03D716) is “1” and bit 7 is “1”, input via AN0 to AN7 isoutput from ANEX0. The input from ANEX1 is converted from analog to digital and the result stored in thecorresponding A-D register. The speed of A-D conversion depends on the response of the external operationamp. Do not connect the ANEX0 and ANEX1 pins directly. Figure 1.20.9 is an example of how toconnect the pins in external operation amp mode.Resistor ladderSuccessive conversion registerAnaloginputAN0AN1AN2AN3AN4AN5AN6AN7ANEX0ANEX1External op-ampComparatorFigure 1.20.9. Example of external op-amp connection mode161