PIC18F2220 Datasheet, PDF (216/388 Pages) Microchip Technology – 28/40/44-Pin High-Performance, Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC18F2220/2320/4220/4320
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 19-1:
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 19-1.
10-bit
Converter
A/D
Reference
Voltage
CHS3:CHS0
1100
1011
1010
1001
1000
0111
0110
0101
VAIN
(Input Voltage)
0100
0011
0010
VCFG1:VCFG0
VREFH
VREFL
AVDD
X0
X1
1X
0X
0001
0000
AVSS
Note 1: Channels AN5 through AN7 are not available on PIC18F2X20 devices.
2: I/O pins have diode protection to VDD and VSS.
AN12⁽²⁾
AN11
AN10
AN9
AN8
AN7⁽¹⁾
AN6⁽¹⁾
AN5⁽¹⁾
AN4
AN3/VREF+
AN2/VREF-
AN1
AN0
DS39599C-page 214
 2003 Microchip Technology Inc.