h8s-2646 Renesas Electronics Corporation., h8s-2646 Datasheet - Page 643

• Manufacturer Part Number: h8s-2646
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

16.6
The following points should be noted when using the A/D converter.
Setting Range of Analog Power Supply and Other Pins:
(1) Analog input voltage range
(2) Relation between AV
(3) V
If conditions (1), (2), and (3) above are not met, the reliability of the device may be adversely
affected.
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 AN11), analog
reference power supply (V
Also, the analog ground (AV
the board.
Notes on Noise Countermeasures: A protection circuit connected to prevent damage due to an
abnormal voltage such as an excessive surge at the analog input pins (AN0 to AN11) and analog
reference power supply (V
figure 16.7.
Also, the bypass capacitors connected to AV
to AN11 must be connected to AV
If a filter capacitor is connected as shown in figure 16.7, the input currents at the analog input pins
(AN0 to AN11) are averaged, and so an error may arise. Also, when A/D conversion is performed
frequently, as in scan mode, if the current charged and discharged by the capacitance of the
The voltage applied to analog input pin ANn during A/D conversion should be in the range
AV
As the relationship between AV
AV
The analog reference voltage input at the V
ref
SS
CC
input range
≤ ANn ≤ V
= V
Usage Notes
CC
, and do not leave the AV
ref
.
CC
ref
ref
, AV
), and analog power supply (AV
) should be connected between AV
SS
) should be connected at one point to a stable digital ground (V
SS
and V
SS
SS
.
and V
CC
CC
, V
and AV
SS
SS
CC
, set AV
ref
and V
pin set in the range V
SS
pins open or no account.
ref
SS
and the filter capacitor connected to AN0
= V
Rev. 5.00 Sep 22, 2005 page 617 of 1136
SS
CC
. If the A/D converter is not used, set
) by the analog ground (AV
CC
and AV
ref
Section 16 A/D Converter
≤ AV
SS
as shown in
CC
.
REJ09B0257-0500
SS
).
SS
) on