PIC18F6585 Datasheet, PDF (254/496 Pages) Microchip Technology – 64/68/80-Pin High-Performance, 64-Kbyte Enhanced Flash Microcontrollers with ECAN Module

PIC18F6585/8585/6680/8680
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- 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.
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.
FIGURE 19-1:
A/D BLOCK DIAGRAM
10-bit
Converter
A/D
Reference
Voltage
VAIN
(Input Voltage)
VCFG1:VCFG0
VREF+
VREF-
VDD
CHS3:CHS0
1111
1110
1101
1100
1011
1010
1001
1000
0111
0110
0101
0100
0011
0010
0001
0000
AN15⁽¹⁾
AN14⁽¹⁾
AN13⁽¹⁾
AN12⁽¹⁾
AN11
AN10
AN9
AN8
AN7
AN6
AN5
AN4
AN3
AN2
AN1
AN0
VSS
Note 1: Channels AN15 through AN12 are not available on the PIC18F6X8X.
2: I/O pins have diode protection to VDD and VSS.
DS30491C-page 252
 2004 Microchip Technology Inc.