CHAPTER 10 8-BIT A/D CONVERTER (µPD789426 AND 789446 SUBSERIES)
Figure 10-11. A/D Conversion End Interrupt Request Generation Timing
Rewriting to ADM0
(to begin conversion
for ANIn)
Rewriting to ADM0
(to begin conversion
for ANIm)
ADIF0 has been set, but conversion
for ANIm has not been completed.
A/D conversion
ANIm
ANIn
ANIn
ANIm
ANIn
ANIm
ANIn
ANIm
ADCR0
INTAD0
Remarks 1. n = 0 to 5
2. m = 0 to 5
(9) AVDD pin
The AVDD pin is used to supply power to the analog circuit. It is also used to supply power to the ANI0 to
ANI5 input circuit.
If your application is designed to be changed to backup power, the AVDD pin must be supplied with the
same voltage level as the VDD pin, as shown in Figure 10-12.
Figure 10-12. AVDD Pin Handling
V
DD
AVDD
Backup
Main power
source
capacitor
V
SS
AVSS
(10) AVDD pin input impedance
A series resistor string of several ten of kΩ is connected between the AVDD and AVSS pins. Consequently, if
the output impedance of the reference voltage supply is high, the reference voltage supply will form a
parallel connection with the series resistor string, creating a large reference voltage differential.
User’s Manual U15075EJ1V0UM00
195
NEC [ NEC ]
