Figure 22.7 Example Of Analog Input Protection Circuit; Figure 22.8 Analog Input Pin Equivalent Circuit - Renesas H8S/2158 User Manual

If a filter capacitor is connected, the input currents at the analog input pins (AN2 to AN7) are
averaged, and so an error may arise. Also, when A/D conversion is performed 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
the analog input pin voltage. Careful consideration is therefore required when deciding the circuit
constants.
* 1 * 1
Notes: Values are reference values.
1.
2.

Figure 22.7 Example of Analog Input Protection Circuit

100 Ω
* 2
R
in
0.1 µF
10 µF 0.01 µF
R : Input impedance
in
10 kΩ
AN7 to AN2
Note: Values are reference values.

Figure 22.8 Analog Input Pin Equivalent Circuit

Section 22 A/D Converter
AVCC
AVref
AN2 to AN7
AVSS
To A/D converter
20 pF
Rev. 3.00 Jan 25, 2006 page 713 of 872
), an error will arise in
in
REJ09B0286-0300