Notes On A/D Converter - NEC mPD178054 Series User Manual

10.5 Notes on A/D Converter

(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
stopping the conversion operation (by resetting bit 7 (ADCS3) of A/D converter mode register 3 (ADM3) to
0).
Figure 10-10 shows how to reduce the current consumption in the standby mode.
Figure 10-10. Example of Reducing Current Consumption in Standby Mode
(2) Input range of ANI0 to ANI5
The input voltages of ANI0 to ANI5 should be within the specified range. In particular, if a voltage above V
or below GND 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 conversion completion
interrupt request signal (INTAD3) generated.
CHAPTER 10 A/D CONVERTER
V
DD
P-ch
Series resistor string
GND
User's Manual U15104EJ2V0UD
ADCS3
DD
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