Microchip Technology DV164136 Data Sheet
PIC18F8722 FAMILY
DS39646C-page 274
© 2008 Microchip Technology Inc.
The analog reference voltage is software selectable to
either the device’s positive and negative supply voltage
(V
either the device’s positive and negative supply voltage
(V
DD
and V
SS
), or the voltage level on the RA3/AN3/
V
REF
+ and RA2/AN2/V
REF
- pins.
The A/D converter has a unique feature of being able
to operate while the device is in Sleep mode. To oper-
ate in Sleep, the A/D conversion clock must be derived
from the A/D’s internal RC oscillator.
to operate while the device is in Sleep mode. To oper-
ate in Sleep, the A/D conversion clock must be derived
from the A/D’s internal RC oscillator.
The output of the sample and hold is the input into the
converter, which generates the result via successive
approximation.
converter, which generates the result via successive
approximation.
A device Reset forces all registers to their Reset state.
This forces the A/D module to be turned off and any
conversion in progress is aborted.
This forces the A/D module to be turned off and any
conversion in progress is aborted.
Each port pin associated with the A/D converter can be
configured as an analog input, or as a digital I/O. The
ADRESH and ADRESL registers contain the result of
the A/D conversion. When the A/D conversion is com-
plete, the result is loaded into the ADRESH:ADRESL
register pair, the GO/DONE bit (ADCON0 register) is
cleared and A/D Interrupt Flag bit, ADIF (PIR1<6>), is
set. The block diagram of the A/D module is shown in
Figure 21-1.
configured as an analog input, or as a digital I/O. The
ADRESH and ADRESL registers contain the result of
the A/D conversion. When the A/D conversion is com-
plete, the result is loaded into the ADRESH:ADRESL
register pair, the GO/DONE bit (ADCON0 register) is
cleared and A/D Interrupt Flag bit, ADIF (PIR1<6>), is
set. The block diagram of the A/D module is shown in
Figure 21-1.
FIGURE 21-1:
A/D BLOCK DIAGRAM
(Input Voltage)
V
AIN
V
REF
+
Reference
Voltage
AV
DD
VCFG<1:0>
CHS<3:0>
AN7
AN6
AN5
AN4
AN3
AN2
AN1
AN0
0111
0110
0101
0100
0011
0010
0001
0000
10-Bit
A/D
V
REF
-
AV
SS
Converter
AN12
(1)
AN11
AN10
AN9
AN8
1100
1011
1010
1001
1000
Note 1:
Channels AN12 through AN15 are not available on 64-pin devices.
2:
I/O pins have diode protection to V
DD
and V
SS
.
0
X
1
X
X
1
X
0
AN15
(1)
AN14
(1)
AN13
(1)
1111
1110
1101