RL78/G10 CHAPTER 10 A/D CONVERTER
R01UH0384EJ0311 Rev. 3.11 263
Dec 22, 2016
Figure 10-23. Analog Input Pin Connection
V
DD
ANI0 to ANI6
Note
Reference
voltage
input
C = 10 pF to 0.1 µF
If there is a possibility that noise equal to or higher than
V
DD
or equal to or lower than V
SS
may enter, clamp with
a diode with a small V
F
value (0.3 V or lower).
Note For 10-pin products, ANI0 to ANI3.
10.9.5 Analog input (ANIn) pins
<1> The analog input pins (ANI0 to ANI6
Note 1
) are also used as input port pins (P01 to P07
Note 2
).
When A/D conversion is performed with any of the ANI0 to ANI6 pins selected, do not change output value to
alternate port P01 to P07
Note 2
while conversion is in progress; otherwise the conversion resolution may be
degraded.
<2> If a pin adjacent to a pin that is being A/D converted is used as a digital I/O port pin, the A/D conversion result
might differ from the expected value due to a coupling noise. Be sure to prevent such a pulse from being input
or output.
Notes 1. For 10-pin products, ANI0 to ANI3.
2. P05 to P07 are provided only in the 16-pin products.
10.9.6 Input impedance of analog input (ANIn) pins
This A/D converter charges a sampling capacitor for sampling during sampling time.
Therefore, only a leakage current flows when sampling is not in progress, and a current that charges the capacitor
flows during sampling. Consequently, the input impedance fluctuates depending on whether sampling is in progress, and
on the other states.
To make sure that sampling is effective, however, it is recommended to keep the output impedance of the analog input
source to within 1 kΩ, and to connect a capacitor of about 0.1 μF to the ANI0 to ANI6
Note
pins (see Figure 10-23).
Note For 10-pin products, ANI0 to ANI3.
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