PIC18F6390 Datasheet, PDF (236/412 Pages) Microchip Technology – 64/80-Pin Flash Microcontrollers with LCD Driver and nanoWatt Technology

PIC18F6390/6490/8390/8490
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+/SEG17 and RA2/AN2/VREF-/SEG16
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 18-1:
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 the A/D Interrupt Flag bit, ADIF, is set. The
block diagram of the A/D module is shown in
Figure 18-1.
CHS3:CHS0
10-bit
Converter
A/D
VAIN
(Input Voltage)
Reference
Voltage
VCFG1:VCFG0
VREF+
VREF-
AVDD
X0
X1
1X
0X
1011
1010
1001
1000
0111
0110
0101
0100
0011
0010
0001
0000
AN11
AN10
AN9
AN8
AN7
AN6
AN5
AN4
AN3
AN2
AN1
AN0
AVSS
Note 1: I/O pins have diode protection to VDD and VSS.
DS39629B-page 234
Preliminary
 2004 Microchip Technology Inc.