h8s-2649 Renesas Electronics Corporation., h8s-2649 Datasheet - Page 528

• Manufacturer Part Number: h8s-2649
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

Section 15 A/D Converter
15.7.6
A protection circuit should be connected in order to prevent damage due to abnormal voltage, such
as an excessive surge at the analog input pins (AN0 to AN15), between AVcc and AVss, as shown
in figure 15.7. Also, the bypass capacitors connected to AVcc and the filter capacitor connected to
AN0 to AN15 must be connected to AVss.
If a filter capacitor is connected, the input currents at the analog input pins (AN0 to AN15) 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 circuit
constants.
Rev. 2.00 Dec. 05, 2005 Page 490 of 724
REJ09B0200-0200
Notes on Noise Countermeasures
Notes: Values are reference values.
*
1
Figure 15.7 Example of Analog Input Protection Circuit
1.
2. R
10 µF
in
: Input impedance
R
in
*
2
0.01 µF
0.1 µF
100 Ω
AVCC
AN0 to AN15
AVSS
in
), an error will arise in