CHAPTER 10 A/D CONVERTER
Preliminary User’s Manual U16846EJ1V0UD
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(8) Conversion
time
This expresses the time since sampling has been started until digital output is obtained.
The sampling time is included in the conversion time in the characteristics table.
(9) Sampling
time
This is the time the analog switch is turned on for the analog voltage to be sampled by the sample & hold circuit.
Sampling
time
Conversion time
10.6 Cautions for A/D Converter
(1) Operating current in standby mode
The A/D converter stops operating in the standby mode. At this time, the operating current can be reduced by
clearing bit 7 (ADCS) of the A/D converter mode register (ADM) to 0 (see Figure 10-2).
(2) Input range of ANI0 to ANI3
Observe the rated range of the ANI0 to ANI3 input voltage. If a voltage of AV
REF
or higher and AV
SS
or lower
(even in the range of absolute maximum ratings) is input to an analog input channel, the converted value of that
channel becomes undefined. In addition, the converted values of the other channels may also be affected.
(3) Conflicting
operations
<1> Conflict between A/D conversion result register (ADCR) write and ADCR read by instruction upon the end
of conversion
ADCR read has priority. After the read operation, the new conversion result is written to ADCR.
<2> Conflict between ADCR write and A/D converter mode register (ADM) write or analog input channel
specification register (ADS) write upon the end of conversion
ADM or ADS write has priority. ADCR write is not performed, nor is the conversion end interrupt signal
(INTAD) generated.