PIC18F2480_09 Datasheet, PDF (256/490 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology

PIC18F2480/2580/4480/4580
The analog reference voltage is software-selectable to
either the device’s positive and negative supply voltage
(AVDD and AVSS), or the voltage level on the
RA3/AN3/VREF+ and RA2/AN2/VREF-/CVREF 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.
The output of the sample and hold is the input into the
converter, which generates the result via successive
approximation.
FIGURE 20-1:
A/D BLOCK DIAGRAM
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.
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
registers, the GO/DONE bit (ADCON0 register) is
cleared and A/D Interrupt Flag bit, ADIF, is set. The
block diagram of the A/D module is shown in
Figure 20-1.
10-Bit
A/D
Converter
Reference
Voltage
CHS<3:0>
1010
1001
1000
0111
0110
0101
VAIN
(Input Voltage)
0100
0011
0010
VREF+
VREF-
VCFG<1:0>
AVDD⁽²⁾
X0
X1
1X
0X
AVSS⁽²⁾
0001
0000
AN10
AN9
AN8
AN7⁽¹⁾
AN6⁽¹⁾
AN5⁽¹⁾
AN4
AN3
AN2
AN1
AN0
Note 1: Channels, AN5 through AN7, are not available on PIC18F2X80 devices.
2: I/O pins have diode protection to VDD and VSS.
DS39637D-page 256
© 2009 Microchip Technology Inc.