HD6412373R RENESAS [Renesas Technology Corp], HD6412373R Datasheet - Page 887

• Manufacturer Part Number: HD6412373R
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

17.7.3
Adding capacitance results in coupling with GND, and therefore noise in GND may adversely
affect absolute precision. Be sure to make the connection to an electrically stable GND such as
AVss.
Care is also required to insure that filter circuits do not communicate with digital signals on the
mounting board, so acting as antennas.
17.7.4
If conditions shown below are not met, the reliability of the device may be adversely affected.
• Analog input voltage range
• Relation between AVcc, AVss and Vcc, Vss
• Vref setting range
17.7.5
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), analog
reference power supply (Vref), 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.
17.7.6
A protection circuit connected to prevent damage due to an abnormal voltage such as an excessive
surge at the analog input pins (AN0 to AN15) should be connected between AVcc and AVss as
shown in figure 17.7. Also, the bypass capacitors connected to AVcc and the filter capacitor
connected to AN0 to AN15 must be connected to AVss.
The voltage applied to analog input pin ANn during A/D conversion should be in the range
AVss ≤ AVn ≤ Vref.
As the relationship between AVcc, AVss and Vcc, Vss, set AVcc ≥ Vcc and AVss = Vss. If
the A/D converter is not used, the AVcc and AVss pins must not be left open.
The reference voltage at the Vref pin should be set in the range Vref ≤ AVcc.
Influences on Absolute Precision
Setting Range of Analog Power Supply and Other Pins
Notes on Board Design
Notes on Noise Countermeasures
Rev.7.00 Mar. 18, 2009 page 819 of 1136
Section 17 A/D Converter
REJ09B0109-0700