NEC mPD780344 Series User Manual page 225

CHAPTER 12 8-BIT A/D CONVERTER ( µ PD780344, 780344Y SUBSERIES)
(6) ANI0 to ANI7 pins
These are eight analog input pins used to input analog signals to undergo A/D conversion to the A/D converter.
ANI0 to ANI7 are alternate-function pins that can also be used for digital inputs.
Cautions 1. Use the ANI0 to ANI7 input voltages within the specification range. If a voltage higher than
or equal to AV
maximum rating range), the conversion value of that channel will be undefined and the
conversion values of other channels may also be affected.
2. Analog input (ANI0 to ANI7) pins are alternate function pins that can also be used as input
port (P10 to P17) pins. When A/D conversion is performed by selecting any one of ANI0
to ANI7, do not access port 1 during conversion, as this may cause a lower conversion
resolution.
3. When a digital pulse is applied to a pin adjacent to the pin being A/D converted, A/D
conversion values may not be obtained as expected due to coupling noise. Thus, do not
apply any pulse to a pin adjacent to the pin being A/D converted.
(7) AV pin
DD
This pin inputs the A/D converter analog power supply.
Use this pin at the same potential as the V
Signals input to ANI0 to ANI7 are converted into digital signals according to the voltage applied between AV
and AV .
SS
Caution A series resistor string of several 10 kΩ is connected between the AV
Therefore, when the output impedance of the reference voltage is too high, it seems as if the
AV pin and the series resistor string are connected in series. This may cause a greater
DD
reference voltage error.
(8) AV pin
SS
This is the ground potential pin of the A/D converter. Always keep it at the same potential as the V
pin even when not using the A/D converter.
or lower than or equal to AV
DD
or V pin even when the A/D converter is not used.
DD0 DD1
User's Manual U15798EJ2V0UD
is applied (even if within the absolute
SS
pin and AV
DD
DD
pin.
SS
or V
SS0 SS1
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