NEC 78K0/KD1 Series User Manual page 236

(2) Power-fail detection function (when PFEN = 1)
By setting bit 7 (ADCS) of the A/D converter mode register (ADM) to 1 and bit 7 (PFEN) of the power-fail
comparison mode register (PFM) to 1, the A/D conversion operation of the voltage applied to the analog input pin
specified by the analog input channel specification register (ADS) is started.
When the A/D conversion has been completed, the result of the A/D conversion is stored in the A/D conversion
result register (ADCR), the values are compared with power-fail comparison threshold register (PFT), and an
interrupt request signal (INTAD) is generated under the condition specified by bit 6 (PFCM) of PFM.
<1> When PFEN = 0
INTAD is generated at the end of each A/D conversion.
<2> When PFEN = 1 and PFCM = 0
The ADCR and PFT values are compared when A/D conversion ends and INTAD is only generated when
ADCR ≥ PFT.
<3> When PFEN = 1 and PFCM = 1
The ADCR and PFT values are compared when A/D conversion ends and INTAD is only generated when
ADCR < PFT.
Figure 12-12. Power-Fail Detection (When PFEN = 1 and PFCM = 0)
A/D conversion
ADCR
PFT
INTAD
(PFEN = 1)
First conversion
Note If the conversion result is not read before the end of the next conversion after INTAD is output, the result is
replaced by the next conversion result.
Remark n = 0 to 7
236
CHAPTER 12 A/D CONVERTER
ANIn ANIn
80H
80H
Note
Condition match
Preliminary User's Manual U16315EJ1V0UD
ANIn ANIn
7FH 80H