PIC18F6390 Datasheet, PDF (240/412 Pages) Microchip Technology – 64/80-Pin Flash Microcontrollers with LCD Driver and nanoWatt Technology

PIC18F6390/6490/8390/8490
18.4 Operation in Power Managed
Modes
The selection of the automatic acquisition time and A/D
conversion clock is determined in part by the clock
source and frequency while in a power managed mode.
If the A/D is expected to operate while the device is in
a power managed mode, the ACQT2:ACQT0 and
ADCS2:ADCS0 bits in ADCON2 should be updated in
accordance with the power managed mode clock that
will be used. After the power managed mode is
entered, an A/D acquisition or conversion may be
started. Once an acquisition or conversion is started,
the device should continue to be clocked by the same
power managed mode clock source until the conver-
sion has been completed. If desired, the device may be
placed into the corresponding Power Managed Idle
mode during the conversion.
If the power managed mode clock frequency is less
than 1 MHz, the A/D RC clock source should be
selected.
Operation in the Sleep mode requires the A/D FRC
clock to be selected. If bits ACQT2:ACQT0 are set to
‘000’ and a conversion is started, the conversion will be
delayed one instruction cycle to allow execution of the
SLEEP instruction and entry to Sleep mode. The IDLEN
and SCS bits in the OSCCON register must have
already been cleared prior to starting the conversion.
18.5 Configuring Analog Port Pins
The ADCON1, TRISA and TRISF registers all
configure the A/D port pins. The port pins needed as
analog inputs must have their corresponding TRIS bits
set (input). If the TRIS bit is cleared (output), the digital
output level (VOH or VOL) will be converted.
The A/D operation is independent of the state of the
CHS3:CHS0 bits and the TRIS bits.
Note 1: When reading the Port register, all pins
configured as analog input channels will
read as cleared (a low level). Pins config-
ured as digital inputs will convert an
analog input. Analog levels on a digitally
configured input will be accurately
converted.
2: Analog levels on any pin defined as a
digital input may cause the digital input
buffer to consume current out of the
device’s specification limits.
DS39629B-page 238
Preliminary
 2004 Microchip Technology Inc.