A/D Converter Usage Notes; Setting Analog Input Voltage; Handling Of Analog Input Pins - Hitachi SH7032 Hardware Manual

14.7

A/D Converter Usage Notes

When using the A/D converter, note the points listed in section 14.7.1 below.
14.7.1

Setting Analog Input Voltage

• Analog Input Voltage Range: During A/D conversion, the voltages input to the analog input
pins ANn should be in the range AV
• Relationships of AV
related as follows: AV
AV = V and AV
CC CC
• AV
Input Range: The analog reference voltage input at the AV
ref
≤ AV
AV . If the converter is not used, set AV
ref CC
• When the converter is neither in use nor in standby mode, connect AV
power voltage (V
14.7.2

Handling of Analog Input Pins

To prevent damage from voltage surges at the analog input pins (AN0–AN7), connect an input
protection circuit like the one shown in figure 14.8. The circuit shown also includes an RC filter to
prevent errors due to noise. This circuit is shown as an example: The circuit constants should be
selected according to actual application conditions. Table 14.5 list the analog input pin
specifications and figure 14.9 shows an equivalent circuit diagram of the analog input ports.
*
Note: *
10 µF
Figure 14.8 Example of Analog Input Protection Circuit
SS
and AV to V
CC SS
= V ± 10% and AV
CC CC
= V .
SS SS
).
CC
100 Ω
*
0.1 µF
0.01 µF
≤ ANn ≤ AV
.
ref
and V : AV , AV
CC SS CC
= V . If the A/D converter is not used, set
SS SS
= V
ref CC
AV
CC
AV
ref
SuperH microcomputer
AN0–AN7
AV
SS
, V and V should be
SS CC SS
pin should be in the range
ref
.
and AV
CC
to the
ref
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