HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 1012

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 27
27.7.7
Connect a protective circuit between AVcc and AVss, as shown in figure 27.9, to prevent damage
of analog input pins (AN0 to AN3) due to abnormal voltage such as excessive serge. Connect a
bypass capacitor that is connected to AVcc and a capacitor for a filter that is connected to AN0 to
AN3 to AVss.
When a capacitor for a filter is connected, input currents of AN0 to AN3 are averaged, may
causing errors. If A/D conversion is frequently performed in scan mode, voltages of analog input
pins cause errors when a current that is charged/discharged for capacitance of a sample & hold
circuit in the A/D converter is higher than a current that is input through input impedance (Rin).
Therefore, determine a circuit constant carefully.
Table 27.5 Analog Input Pin Ratings
Rev. 3.00
REJ09B0033-0300
Item
Analog input capacitance
Allowable signal-source impedance
Notes on Countermeasures to Noise
Jan. 18, 2008
A/D Converter
Notes: *1 Values are for reference.
Figure 27.9
*
1
*2 R
Page 950 of 1458
10 µF
in
is input impedance.
R
in
*
2
Example of Analog Input Protection Circuit
0.01 µF
0.1 µF
100 Ω
Min


AV
AN0 to AN3
AV
CC
SS
(A/D)
(A/D)
Max
20
5
This LSI
Unit
pF
kΩ