PCM18XT0 Microchip Technology, PCM18XT0 Datasheet - Page 255

• Manufacturer Part Number: PCM18XT0
• Description: MODULE PROC PIC18F4685
• Manufacturer: Microchip Technology

Specifications of PCM18XT0

• Accessory Type: Processor Module
• Product: Microcontroller Modules
• Core Processor: PIC18F4685
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: ICE2000
• For Use With: ICE2000 - EMULATOR MPLAB-ICE 2000 POD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Not applicable / Not applicable

19.2
The ADCON2 register allows the user to select an
acquisition time that occurs each time the GO/DONE
bit is set.
When the GO/DONE bit is set, sampling is stopped and
a conversion begins. The user is responsible for ensur-
ing the required acquisition time has passed between
selecting the desired input channel and setting the
GO/DONE bit. This occurs when the ACQT2:ACQT0
bits (ADCON2<5:3>) remain in their Reset state (‘000’)
and is compatible with devices that do not offer
programmable acquisition times.
If desired, the ACQT bits can be set to select a
programmable acquisition time for the A/D module.
When the GO/DONE bit is set, the A/D module
continues to sample the input for the selected
acquisition
conversion. Since the acquisition time is programmed,
there may be no need to wait for an acquisition time
between selecting a channel and setting the GO/DONE
bit.
In either case, when the conversion is completed, the
GO/DONE bit is cleared, the ADIF flag is set and the
A/D begins sampling the currently selected channel
again. If an acquisition time is programmed, there is
nothing to indicate if the acquisition time has ended or
if the conversion has begun.
TABLE 19-1:
© 2009 Microchip Technology Inc.
Note 1:
2:
3:
4:
Operation
16 T
32 T
64 T
Selecting and Configuring
Automatic Acquisition Time
2 T
4 T
8 T
RC
The RC source has a typical T
The RC source has a typical T
For device frequencies above 1 MHz, the device must be in Sleep for the entire conversion or the A/D
accuracy may be out of specification.
Low-power (PIC18LFXXXX) devices only.
OSC
OSC
OSC
OSC
OSC
OSC
AD Clock Source (T
time,
(3)
T
AD
then
vs. DEVICE OPERATING FREQUENCIES
automatically
ADCS2:ADCS0
AD
000
100
001
101
010
110
x11
)
AD
AD
begins
time of 1.2 μs.
time of 2.5 μs.
PIC18F2682/2685/4682/4685
PIC18F2682/2685/4682/4685 PIC18LF2682/2685/4682/4685
a
22.86 MHz
11.43 MHz
2.86 MHz
5.71 MHz
40.0 MHz
40.0 MHz
1.00 MHz
19.3
The A/D conversion time per bit is defined as T
A/D conversion requires 11 T
The source of the A/D conversion clock is software
selectable. There are seven possible options for T
• 2 T
• 4 T
• 8 T
• 16 T
• 32 T
• 64 T
• Internal RC Oscillator
For correct A/D conversions, the A/D conversion clock
(T
minimum T
for more information).
Table 19-1 shows the resultant T
the device operating frequencies and the A/D clock
source selected.
AD
) must be as short as possible, but greater than the
OSC
OSC
OSC
Maximum Device Frequency
OSC
OSC
OSC
(1)
Selecting the A/D Conversion
Clock
AD
(approximately 2 μs, see parameter 130
AD
1.00 MHz
11.43 MHz
22.86 MHz
22.86 MHz
2.86 MHz
5.72 MHz
per 10-bit conversion.
1.43 kHz
AD
DS39761C-page 255
times derived from
(2)
AD
. The
AD
(4)
: