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CHAPTER 13 A/D CONVERTER
User’s Manual U12697EJ3V0UM
13.6 Cautions
(1) Current consumption in standby mode
The A/D converter operation is stopped during the standby mode. At this time, the current consumption can be
reduced by setting bit 7 (ADCS) of the A/D converter mode register (ADM) to 0 or by stopping the reference voltage
circuit (bit of ADM (ADCE) = 0).
The method to reduce the current consumption in the standby mode is shown in Figure 13-14.
Figure 13-14. Method to Reduce Current Consumption in Standby Mode
Series resistor string
Reference voltage circuit
ADCS
ADCE
P-ch
AV
DD
AV
SS
(2) ANI0 to ANI7 input range
Use ANI0 to ANI7 input voltages within the rated voltage range. Inputting a voltage equal to or greater than AV
DD
,
or equal to or smaller than AV
SS
(even if within the absolute maximum rated range) will cause the channel’s
conversion values to become undefined, or may affect the conversion values of other channels.
(3) Contention operation
<1>
Contention with ADCR read due to contention between A/D conversion result register (ADCR) write
and instruction at conversion end
The read operation to ADCR is prioritized. After the read operation, a new conversion result is written to
ADCR.
<2>
Contention between ADCR write and external trigger signal input at conversion end
External trigger signals cannot be received during A/D conversion. Therefore, external trigger signals during
ADCR write operation are not received.
<3>
Contention between ADCR write and A/D converter mode register (ADM) write, or between A/D
converter input selection register (ADIS) write at conversion end
The write operation to ADM or ADIS is prioritized. Write to ADCR is not performed. Moreover, no interrupt
signal (INTAD) is issued at conversion end.
