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CHAPTER 11
A/D CONVERTER
User’s Manual U12790EJ2V0UD
11.5 A/D Converter Cautions
(1) Current consumption in standby mode
The A/D converter is stopped in the standby mode. At this time, the current consumption can be reduced by
resetting bit 7 (ADCS3) of A/D converter mode register 3 (ADM3) to 0.
Figure 11-10 shows the circuit configuration of the series resistor string.
Figure 11-10. Circuit Configuration of Series Resistor String
(2) Input range of ANI0 to ANI7
The input voltages of ANI0 to ANI7 should be within the specification range. In particular, if a voltage of AVDD
or above or AVSS or below is input (even if within the absolute maximum rating range), the conversion value
for that channel will be undefined. The conversion values of the other channels may also be affected.
(3) Conflicting operations
<1> Conflict between writing A/D conversion result register 3 (ADCR3) on completion of conversion and
reading ADCR3 by an instruction
Reading ADCR3 takes precedence. After ADCR3 has been read, a new conversion result is written
to ADCR3.
<2> Conflict between writing ADCR3 on completion of conversion and writing A/D converter mode register
3 (ADM3) or writing analog input channel specification register 3 (ADS3)
Writing ADM3 or ADS3 takes precedence. ADCR3 is not written. Nor is the A/D conversion end interrupt
request signal (INTAD) generated.
AVDD
AVSS
P-ch
Series resistor string
ADCS3