DV164136 Microchip Technology, DV164136 Datasheet - Page 279

• Manufacturer Part Number: DV164136
• Description: DEVELOPMENT KIT FOR PIC18
• Manufacturer: Microchip Technology
• Series: PIC®r
• Type: MCUr

Specifications of DV164136

• Contents: Board, Cables, CDs, PICkit™ 3 Programmer, Power Supply
• Processor To Be Evaluated: PIC18F8722, PIC18F87J11
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3.3 V, 5 V
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18F8xxx
• Kit Contents: PIC18 Exp Brd PICkit 3 Cable CD PSU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PIC18F8722, PIC18F87J11
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

21.2
The ADCON2 register allows the user to select an
acquisition time that occurs each time the GO/DONE
bit is set. It also gives users the option to use an
automatically determined acquisition time.
Acquisition time may be set with the ACQT<2:0> bits
(ADCON2<5:3>) which provides a range of 2 to 20 T
When the GO/DONE bit is set, the A/D module
continues to sample the input for the selected acquisi-
tion time, then automatically begins a 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.
Manual
ACQT<2:0> = 000. When the GO/DONE bit is set,
sampling is stopped and a conversion begins. The user
is responsible for ensuring the required acquisition time
has passed between selecting the desired input
channel and setting the GO/DONE bit. This option is
also the default Reset state of the ACQT<2:0> bits and
is compatible with devices that do not offer
programmable acquisition times.
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 21-1:
© 2008 Microchip Technology Inc.
Note 1:
Operation
16 T
32 T
64 T
2 T
4 T
8 T
2:
3:
4:
RC
Selecting and Configuring
Acquisition Time
OSC
OSC
OSC
OSC
OSC
OSC
(3)
AD Clock Source (T
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.
acquisition
T
AD
vs. DEVICE OPERATING FREQUENCIES
ADCS<2:0>
is
000
100
001
101
010
110
x11
AD
selected
)
AD
AD
time of 1.2 μs.
time of 2.5 μs.
when
AD
.
PIC18FXXXX
1.00 MHz
22.86 MHz
11.43 MHz
2.86 MHz
5.71 MHz
40.0 MHz
40.0 MHz
21.3
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
more information).
Table 21-1 shows the resultant T
the device operating frequencies and the A/D clock
source selected.
PIC18F8722 FAMILY
AD
Maximum Device Frequency
) must be as short as possible, but greater than the
OSC
OSC
OSC
(1)
OSC
OSC
OSC
Selecting the A/D Conversion
Clock
AD
(see parameter 130, Table 28-27 for
PIC18LFXXXX
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
DS39646C-page 277
times derived from
(2)
(4)
AD
. The
AD
: