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CHAPTER 13 10-BIT A/D CONVERTER ( µ PD780354, 780354Y SUBSERIES)
13.6 A/D Converter Cautions
(1) Power consumption in standby mode
The A/D converter stops operating in the standby mode. At this time, the power consumption can be reduced
by setting bit 7 (ADCS0) of A/D converter mode register 0 (ADM0) to 0.
Figure 13-15 shows the circuit configuration of the series resistor string.
Figure 13-15. Example of Series Resistor String Circuit Configuration
(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 higher
than or equal to AV
or lower than or equal to AV
DD
the conversion value of that channel will be undefined and the conversion values of other channels may also
be affected.
(3) Conflicting operations
<1> Conflict between A/D conversion result register 0 (ADCR0) write and ADCR0 read by instruction upon the
end of conversion
ADCR0 read is given priority. After the read operation, the new conversion result is written to ADCR0.
<2> Conflict between ADCR0 write and external trigger signal input upon the end of conversion
The external trigger signal is not accepted during A/D conversion. Therefore, the external trigger signal
is not accepted during ADCR0 write.
<3> Conflict between ADCR0 write and A/D converter mode register 0 (ADM0) write or analog input channel
specification register 0 (ADS0) write upon the end of conversion
ADM0 or ADS0 write is given priority. ADCR0 write is not performed, nor is the conversion end interrupt
request signal (INTAD0) generated.
AV
DD
P-ch
Series resistor string
AV
SS
is input (even if within the absolute maximum rating range),
SS
User's Manual U15798EJ2V0UD
ADCS0
259
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