Section 22 A/D Converter
Rev. 3.00 Jan 25, 2006 page 712 of 872
REJ09B0286-0300
22.8.3
Setting Range of Analog Power Supply and Other Pins
If conditions shown below are not met, the reliability of this LSI may be adversely affected.
•
Analog input voltage range
The voltage applied to analog input pin ANn during A/D conversion should be in the range
AV
SS
≤
ANn
≤
AV
ref
(n = 2 to 7).
•
Digital input voltage range
The voltage applied to digital input pin CINn should be in the range AV
SS
≤
CINn
≤
AV
ref
and
V
SS
≤
CINn
≤
V
CC
(n = 0 to 7).
•
Relation between AV
CC
, AV
SS
and V
CC
, V
SS
For 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 AVCC and AVSS pins must on no account be left open.
•
AVref pin reference voltage specification range
The reference voltage of the AVref pin should be in the range AV
ref
≤
AV
CC
.
•
It is not recommended to use the D/A converter or A/D converter simultaneously with the USB
because the bus driver/receiver power supply pin DrVCC/DrVSS is shared with the analog
power supply pin AVCC/AVSS.
22.8.4
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 (AN2 to AN7), analog reference voltage
(AV
ref
), and analog power supply (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.
22.8.5
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 (AN2 to AN7) and analog reference voltage (AV
ref
) should be
connected between AVCC and AVSS as shown in figure 22.7. Also, the bypass capacitors
connected to AVCC and AVref, and the filter capacitors connected to AN7 to AN2 must be
connected to AVSS.
Содержание H8S/2158
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Страница 70: ...Section 1 Overview Rev 3 00 Jan 25 2006 page 16 of 872 REJ09B0286 0300...
Страница 118: ...Section 3 MCU Operating Modes Rev 3 00 Jan 25 2006 page 64 of 872 REJ09B0286 0300...
Страница 126: ...Section 4 Exception Handling Rev 3 00 Jan 25 2006 page 72 of 872 REJ09B0286 0300...
Страница 198: ...Section 6 Bus Controller Rev 3 00 Jan 25 2006 page 144 of 872 REJ09B0286 0300...
Страница 326: ...Section 10 8 Bit PWM Timer PWM Rev 3 00 Jan 25 2006 page 272 of 872 REJ09B0286 0300...
Страница 440: ...Section 15 Watchdog Timer WDT Rev 3 00 Jan 25 2006 page 386 of 872 REJ09B0286 0300...
Страница 606: ...Section 17 I 2 C Bus Interface IIC Rev 3 00 Jan 25 2006 page 552 of 872 REJ09B0286 0300...
Страница 742: ...Section 19 Multimedia Card Interface MCIF Rev 3 00 Jan 25 2006 page 688 of 872 REJ09B0286 0300...
Страница 744: ...Section 20 Encryption Operation Circuit DES and GF Rev 3 00 Jan 25 2006 page 690 of 872 REJ09B0286 0300...
Страница 750: ...Section 21 D A Converter Rev 3 00 Jan 25 2006 page 696 of 872 REJ09B0286 0300...
Страница 768: ...Section 22 A D Converter Rev 3 00 Jan 25 2006 page 714 of 872 REJ09B0286 0300...
Страница 770: ...Section 23 RAM Rev 3 00 Jan 25 2006 page 716 of 872 REJ09B0286 0300...
Страница 824: ...Section 26 Clock Pulse Generator Rev 3 00 Jan 25 2006 page 770 of 872 REJ09B0286 0300...
Страница 844: ...Section 27 Power Down Modes Rev 3 00 Jan 25 2006 page 790 of 872 REJ09B0286 0300...
Страница 878: ...Section 28 List of Registers Rev 3 00 Jan 25 2006 page 824 of 872 REJ09B0286 0300...
Страница 926: ...Index Rev 3 00 Jan 25 2006 page 872 of 872 REJ09B0286 0300...