PIC18F47J53 Datasheet, PDF (377/586 Pages) Microchip Technology – 28/44-Pin, High-Performance USB Microcontrollers with nanoWatt XLP Technology

PIC18F47J53 FAMILY
FIGURE 22-3:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)
TCY - TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11
b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
Conversion starts
Holding capacitor is disconnected from analog input (typically 100 ns)
Set GO/DONE bit
Next Q4: ADRESH/ADRESL are loaded, GO/DONE bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
FIGURE 22-4:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)
TACQT Cycles
TAD Cycles
123
Automatic
Acquisition
Time
412345678
b9 b8 b7 b6 b5 b4 b3
Conversion starts
(Holding capacitor is disconnected)
9 10 11
b2 b1 b0
Set GO/DONE bit
(Holding capacitor continues
acquiring input)
Next Q4: ADRESH:ADRESL are loaded, GO/DONE bit is cleared,
ADIF bit is set, holding capacitor is reconnected to analog input.
22.7 A/D Converter Calibration
The A/D Converter in the PIC18F47J53 family of
devices includes a self-calibration feature, which com-
pensates for any offset generated within the module.
The calibration process is automated and is initiated by
setting the ADCAL bit (ADCON1<6>). The next time
the GO/DONE bit is set, the module will perform an off-
set calibration and store the result internally. Thus,
subsequent offsets will be compensated.
Example 22-1 provides an example of a calibration
routine.
The calibration process assumes that the device is in a
relatively steady-state operating condition. If A/D
calibration is used, it should be performed after each
device Reset or if there are other major changes in
operating conditions.
 2010 Microchip Technology Inc.
Preliminary
DS39964B-page 377