SH7280 Datasheet, PDF (1037/1726 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine family

Section 20 A/D Converter (ADC)
20.7 Usage Notes
20.7.1 Analog Input Voltage Range
The voltage applied to analog input pin (ANn) during A/D conversion should be in the range
AVss ≤ ANn (n = 0 to 11) ≤ AVref.
20.7.2 Relationship between AVcc, AVss and Vcc, Vss
When using the A/D converter, set AVcc = 5.0 V ± 0.5 V and AVss = Vss. When the A/D
converter is not used, set Vcc ≤ AVcc ≤ 5.0V ± 0.5 V, AVss = Vss, and do not leave the AVcc pin
open.
20.7.3 Range of AVREF Pin Settings
Set AVREF = 4.5 V to AVcc when using the A/D converter, or set AVREF = AVcc when not
using the A/D converter. Set AVREFVSS = AVSS, and do not leave the AVREFVSS pin open. If
these conditions are not met, the reliability of the LSI may be adversely affected.
20.7.4 Notes on Board Design
In board design, digital circuitry and analog circuitry should be as mutually isolated as possible,
and the layout in which the digital circuit signal lines and analog circuit signal lines cross or are in
close proximity to each other should be avoided as much as possible. Failure to do so may result in
the incorrect operation of the analog circuitry due to inductance, adversely affecting the A/D
conversion values.
In addition, digital circuitry must be isolated from the analog input signals (AN0 to AN11), analog
reference power supply (AVREF), the analog power supply (AVcc), and the analog ground
(AVss). AVss should be connected at one point to a stable digital ground (Vss) on the board.
Rev. 1.00 Jun. 26, 2008 Page 1007 of 1692
REJ09B0393-0100