SH7032 Datasheet, PDF (453/687 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

Section 14 A/D Converter
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_SS ≤ ANn ≤ AV_ref.
• Relationships of AV_CC and AV_SS to V_CC and V_SS: AV_CC, AV_SS, V_CC and V_SS should be
related as follows: AV_CC = V_CC ± 10% and AV_SS = V_SS. If the A/D converter is not used, set
AV_CC = V_CC and AV_SS = V_SS.
• AV_ref Input Range: The analog reference voltage input at the AV_ref pin should be in the range
AV_ref ≤ AV_CC. If the converter is not used, set AV_ref = V_CC.
• When the converter is neither in use nor in standby mode, connect AV_CC and AV_ref to the
power voltage (V_CC).
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.
**
100 Ω
0.1 µF
AV_CC
AV_ref
SuperH microcomputer
AN0–AN7
AV_SS
Note: *
10 µF
0.01 µF
Figure 14.8 Example of Analog Input Protection Circuit
Rev. 7.00 Jan 31, 2006 page 427 of 658
REJ09B0272-0700