UPD78F0411GA-GAM-AX Datasheet, PDF (311/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 12 10-BIT SUCCESSIVE APPROXIMATION TYPE A/D CONVERTER (μPD78F041x only)
12.6 Cautions for 10-Bit Successive Approximation Type A/D Converter
(1) Operating current in STOP mode
The A/D converter stops operating in the STOP mode. At this time, the operating current can be reduced by
clearing bit 7 (ADCS) and bit 0 (ADCE) of the A/D converter mode register (ADM) to 0.
To restart from the standby status, clear bit 0 (ADIF) of interrupt request flag register 1L (IF1L) to 0 and start
operation.
(2) Input range of ANI0 to ANI5
Observe the rated range of the ANI0 to ANI5 input voltage. If a voltage of AVREF or higher and AVSS 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, ADCRH) write and ADCR or ADCRH read by
instruction upon the end of conversion
ADCR or ADCRH read has priority. After the read operation, the new conversion result is written to ADCR
or ADCRH.
<2> Conflict between ADCR or ADCRH write and A/D converter mode register (ADM) write, analog input
channel specification register (ADS), or A/D port configuration register 0 (ADPC0) write upon the end of
conversion
ADM, ADS, or ADPC0 write has priority. ADCR or ADCRH write is not performed, nor is the conversion
end interrupt signal (INTAD) generated.
(4) Noise countermeasures
To maintain the 10-bit resolution, attention must be paid to noise input to the AVREF pin and pins ANI0 to ANI5.
<1> Connect a capacitor with a low equivalent resistance and a good frequency response to the power supply.
<2> The higher the output impedance of the analog input source, the greater the influence. To reduce the
noise, connecting external C as shown in Figure 12-20 is recommended.
<3> Do not switch these pins with other pins during conversion.
<4> The accuracy is improved if the HALT mode is set immediately after the start of conversion.
User’s Manual U18698EJ1V0UD
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