NEC mPD789101, User Manual

Page: 158 / 265

CHAPTER 12 10-BIT A/D CONVERTER (
µ
PD789114, 789134 SUBSERIES)
User’s Manual U13045EJ2V0UM00
158
12.5 Cautions Related to 10-Bit A/D Converter
(1) Current consumption in the standby mode
When the A/D converter enters the standby mode, it stops its operation. Stopping conversion (bit 7 (ADCS0)
of A/D converter mode register 0 (ADM0) = 0) can reduce the current consumption.
Figure 12-7 shows how to reduce the current consumption in the standby mode.
Figure 12-7. How to Reduce Current Consumption in Standby Mode
(2) Input range for the ANI0 to ANI3 pins
Be sure to keep the input voltage at ANI0 to ANI3 within its rating. If a voltage not lower than AV
DD
or not
higher than AV
SS
(even within the absolute maximum rating) is input a conversion channel, the conversion
output of the channel becomes undefined. It may affect the conversion output of the other channels.
(3) Conflict
<1> Conflict between writing to A/D conversion result register 0 (ADCR0) at the end of conversion and reading
from ADCR0
Reading from ADCR0 takes precedence. After reading, the new conversion result is written to ADCR0.
<2> Conflict between writing to ADCR0 at the end of conversion and writing to A/D converter mode register
0 (ADM0) or A/D input selection register 0 (ADS0)
Writing to ADM0 or ADS0 takes precedence. A request to write to ADCR0 is ignored. No conversion
end interrupt request signal (INTAD0) is generated.
AV
DD
AV
SS
P-ch
Series resistor string
ADCS0