PIC18F2510 MICROCHIP [Microchip Technology], PIC18F2510 Datasheet - Page 221

• Manufacturer Part Number: PIC18F2510
• Description: 28/40/44-PIN FLASH MICROCONTROLLERS WITH 10-BIT A/D AND NANO WATT TECHNOLOGY
• Manufacturer: MICROCHIP [Microchip Technology]

18.6
Figure 18-4 shows the operation of the A/D converter
after the GO bit has been set and the ACQT2:ACQT0
bits are cleared. A conversion is started after the follow-
ing instruction to allow entry into Sleep mode before the
conversion begins.
Figure 18-5 shows the operation of the A/D converter
after the GO bit has been set and the ACQT2:ACQT0
bits are set to ‘010’ and selecting a 4 T
time before the conversion starts.
Clearing the GO/DONE bit during a conversion will
abort the current conversion. The A/D Result register
pair will NOT be updated with the partially completed
A/D
ADRESH:ADRESL registers will continue to contain
the value of the last completed conversion (or the last
value written to the ADRESH:ADRESL registers).
FIGURE 18-4:
FIGURE 18-5:
 2004 Microchip Technology Inc.
(Holding capacitor continues
acquiring input)
Set GO bit
1
conversion
T
Set GO bit
CY
A/D Conversions
T
Holding capacitor is disconnected from analog input (typically 100 ns)
ACQT
Acquisition
Automatic
- T
2
Time
AD
Conversion starts
Cycles
T
AD
3
1 T
sample.
A/D CONVERSION T
A/D CONVERSION T
AD
b9
4
2 T
Conversion starts
(Holding capacitor is disconnected)
AD
1
b8
This
3 T
b9
AD
2
b7
AD
means
4 T
acquisition
On the following cycle:
ADRESH:ADRESL is loaded, GO bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
AD
b8
3
AD
AD
b6
5 T
On the following cycle:
ADRESH:ADRESL is loaded, GO bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
CYCLES (ACQT<2:0> = 000, T
CYCLES (ACQT<2:0> = 010, T
Preliminary
the
AD
4
b7
b5
6 T
T
AD
b4
5
b6
AD
7 T
After the A/D conversion is completed or aborted, a
2 T
started. After this wait, acquisition on the selected
channel is automatically started.
18.7
The discharge phase is used to initialize the value of
the capacitor array. The array is discharged before
every sample. This feature helps to optimize the unity-
gain amplifier, as the circuit always needs to charge the
capacitor array, rather than charge/discharge based on
previous measure values.
Cycles
Note:
AD
b5
b3
AD
6
8
wait is required before the next acquisition can be
PIC18F2X1X/4X1X
T
Discharge
b4
AD
b2
7
The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
9 T
AD
b3
8
b1
10
T
AD
ACQ
b0
b2
9
ACQ
11
= 0)
T
= 4 T
AD
10
b1
Discharge
1
AD
DS39636A-page 219
b0
11
)
T
Discharge
AD
1