NEC 78014Y Series, User Manual

Page: 261 / 547

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CHAPTER 14 A/D CONVERTER
261
(6) Interrupt request flag (ADIF)
The interrupt request flag (ADIF) is not cleared even if the A/D converter mode register (ADM) is changed.
Caution is therefore required since, if a change of analog input pin is performed during A/D conversion, the A/
D conversion result and ADIF for the pre-change analog input may be set just before the ADM rewrite, and when
ADIF is read immediately after the ADM rewrite, ADIF may be set despite the fact that the A/D conversion for
the post-change analog input has not ended. (Refer to Figure 14-10.)
When the A/D conversion is stopped, the ADIF must be cleared before restarting.
Figure 14-10. A/D Conversion End Interrupt Request Generation Timing
(7) AV
DD
pin
The AV
DD
pin is the analog circuit power supply pin, and supplies power to the input circuits of ANI0/P10
to ANI7/P17.
Therefore, be sure to apply the voltage at the same level as V
DD
as shown in Figure 14-11, even in an application
where the power supply is switched to the back-up power supply.
Figure 14-11. AV
DD
Pin Connection
A/D conversion
ADCR
INTAD
Rewriting ADM
(ANln conversion starts)
Rewriting ADM
(ANlm conversion starts)
ADIF is set, but conversion
of ANlm is not completed
ANIn ANIn ANIm ANIm
ANIn ANIn ANIm ANIm
AV
REF
V
DD
AV
DD
V
SS
AV
SS
Back up
Capacitor
Main Power Supply