h8s-2649 Renesas Electronics Corporation., h8s-2649 Datasheet - Page 527

• Manufacturer Part Number: h8s-2649
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

15.7.4
If the conditions below are not met, the reliability of the device may be adversely affected.
• Analog input voltage range
• Relationship between AVcc, AVss and Vcc, Vss
• Setting range of the Vref pin
15.7.5
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 digital ground (Vss) on the board.
The voltage applied to analog input pin ANn during A/D conversion should be in the range
AVss ≤ VNn ≤ AVcc.
Set AVss = Vss as 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.
The reference voltage set by the Vref pin should be in the range Vref ≤ AVcc.
Range of Analog Power Supply and Other Pin Settings
Notes on Board Design
Sensor input
Sensor output
impedance
to 5 kΩ
Low-pass
filter
C to 0.1 µF
Figure 15.6 Example of Analog Input Circuit
This LSI
C
15 pF
in
=
A/D converter
equivalent circuit
Rev. 2.00 Dec. 05, 2005 Page 489 of 724
10 kΩ
Section 15 A/D Converter
20 pF
REJ09B0200-0200