PIC18F2221-E/SO Microchip Technology, PIC18F2221-E/SO Datasheet - Page 239

• Manufacturer Part Number: PIC18F2221-E/SO
• Description: 4KB, Flash, 512bytes-RAM, 25I/O, 8-bit Family,nanoWatt 28 SOIC .300in TUBE
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2221-E/SO

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 25
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

20.2
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
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 20-1:
© 2009 Microchip Technology Inc.
Note 1:
AD
. When the GO/DONE bit is set, the A/D module
2:
3:
4:
Selecting and Configuring
Acquisition Time
Operation
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.
16 T
32 T
64 T
acquisition
2 T
4 T
8 T
RC
OSC
OSC
OSC
OSC
OSC
OSC
(3)
AD Clock Source (T
T
AD
PIC18F2221/2321/4221/4321 FAMILY
vs. DEVICE OPERATING FREQUENCIES
is
selected
AD
ADCS<2:0>
)
AD
AD
000
100
001
101
010
110
x11
time of 1.2
time of 2.5
when
μ
μ
s.
s.
20.3
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
information).
Table 20-1 shows the resultant T
the device operating frequencies and the A/D clock
source selected.
PIC18F2X21/4X21
AD
22.86 MHz
) must be as short as possible, but greater than the
11.43 MHz
1.00 MHz
2.86 MHz
5.71 MHz
40.0 MHz
40.0 MHz
OSC
OSC
OSC
OSC
OSC
OSC
Selecting the A/D Conversion
Clock
Maximum Device Frequency
T
AD
(1)
(see
parameter
PIC18LF2X21/4X21
AD
per 10-bit conversion.
AD
1.00 MHz
11.43 MHz
22.86 MHz
22.86 MHz
2.86 MHz
5.72 MHz
1.43 kHz
DS39689F-page 239
times derived from
130
(2)
for
AD
(4)
. The
more
AD
: