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If a filter capacitor is connected as shown in figure 13-7, the input currents at the analog input pins
(AN
to AN
) are averaged, and so an error may arise. Also, when A/D conversion is performed
0
7
frequently, as in scan mode, if the current charged and discharged by the capacitance of the
sample-and-hold circuit in the A/D converter exceeds the current input via the input impedance
(R
), an error will arise in the analog input pin voltage.Therefore careful consideration is required
in
when deciding the circuit constants.
1
*
Notes:
Values are reference values.
1.
10 µF
2. R
: Input impedance
in
Figure 13-7 Example of Analog Input Protection Circuit
428
100 Ω
2
R
*
in
0.1 µF
0.01 µF
AV
CC
AN
to AN
0
7
AV
SS
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