SH7080 Datasheet, PDF (1031/1644 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 19 A/D Converter (ADC)
Sensor output
impedance of
up to 3 kΩ or
up to 1 kΩ
Sensor input
Low-pass
filter
C to 0.1 µF
This LSI
C_in =
20 pF
A/D converter
equivalent circuit
10 kΩ
20 pF
Figure 19.7 Example of Analog Input Circuit
19.7.4 Range of Analog Power Supply and Other Pin Settings
If the conditions below are not met, the reliability of the device may be adversely affected.
• Analog input voltage range
The voltage applied to analog input pin ANn during A/D conversion should be in the range
AVss ≤ VAN ≤ AV_ref.
• Relationship between AVcc, AVss and Vcc, Vss
Set AVss = Vss for the relationship between AVcc, AVss and Vcc, Vss. If the A/D converter
is not used, the AVcc and AVss pins must not be left open.
• AV_ref input voltage range
The voltage applied to the AV_ref pin should be in the range AV_ref ≤ AVcc.
If the A/D converter is not used, set AV_ref = AVcc.
19.7.5 Notes on Board Design
In board design, digital circuitry and analog circuitry should be as mutually isolated as possible,
and layout in which digital circuit signal lines and analog circuit signal lines cross or are in close
proximity should be avoided as far as possible. Failure to do so may result in incorrect operation
of the analog circuitry due to inductance, adversely affecting A/D conversion values. Also, digital
circuitry must be isolated from the analog input signals (AN0 to AN15), and analog power supply
(AVcc) by the analog ground (AVss). Also, the analog ground (AVss) should be connected at one
point to a stable ground (Vss) on the board.
Rev. 3.00 May 17, 2007 Page 973 of 1582
REJ09B0181-0300