HD64F3039F18 Datasheet, PDF (454/710 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8 Family / H8/300H Series

Section 13 A/D Converter
13.5 Interrupts
The A/D converter generates an interrupt (ADI) at the end of A/D conversion. The ADI interrupt
request can be enabled or disabled by the ADIE bit in ADCSR.
13.6 Usage Notes
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
The voltage applied to analog input pins AN₀ to AN₇ during A/D conversion should be in the
range AV_SS ≤ ANn ≤ AV_CC.
(2) Relation between AV_CC, AV_SS and V_CC, V_SS
As the relationship between AV_CC, AV_SS and V_CC, V_SS, set AV_SS = V_SS. If the A/D converter is
not used, the AV_CC and AV_SS pins must on no account be left open.
If conditions (1) and (2) 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 AN₇), and analog
power supply and reference voltage (AV_CC) by the analog ground (AV_SS). Also, the analog ground
(AV_SS) should be connected at one point to a stable digital ground (V_SS) on 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 AN₇) and analog power supply (AV_CC) should be connected
between AV_CC and AV_SS as shown in figure 13.7.
Also, the bypass capacitors connected to AV_CC and the filter capacitor connected to AN₀ to AN₇
must be connected to AV_SS.
Rev.3.00 Mar. 26, 2007 Page 430 of 682
REJ09B0353-0300