參數(shù)資料
型號(hào)： PIC18F4553
廠商： Microchip Technology Inc.
英文描述： 28/40/44-Pin High-Performance, Enhanced Flash, USB Microcontrollers with 12-Bit A/D and nanoWatt Technology
中文描述： 28/40/44-Pin高性能，增強(qiáng)型閃存，USB微控制器與12位A / D和納瓦技術(shù)
文件頁數(shù)： 27/46頁
文件大?。?/td> 607K
代理商： PIC18F4553
2007 Microchip Technology Inc.
Preliminary
DS39887B-page 25
PIC18F2458/2553/4458/4553
2.2
Selecting and Configuring
Acquisition Time
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 ACQT2:ACQT0
bits (ADCON2<5:3>), which provides a range of 2 to
20 T
AD
. 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
ACQT2:ACQT0 =
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 ACQT2:ACQT0 bits
and is compatible with devices that do not offer
programmable acquisition times.
acquisition
is
selected
when
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.
2.3
Selecting the A/D Conversion
Clock
The A/D conversion time per bit is defined as T
AD
. The
A/D conversion requires 13 T
AD
per 12-bit conversion.
The source of the A/D conversion clock is software
selectable. There are seven possible options for T
AD
:
2 T
OSC
4 T
OSC
8 T
OSC
16 T
OSC
32 T
OSC
64 T
OSC
Internal RC Oscillator
For correct A/D conversions, the A/D conversion clock
(T
AD
) must be as short as possible, but greater than the
minimum T
AD
(see parameter 130 for more
information).
Table 2-1 shows the resultant T
AD
times derived from
the device operating frequencies and the A/D clock
source selected.
TABLE 2-1:
T
AD
vs. DEVICE OPERATING FREQUENCIES
A/D Clock Source (T
AD
)
Assumes T
AD
Min. = 0.8
μ
s
Operation
ADCS2:ADCS0
Maximum F
OSC
2 T
OSC
4 T
OSC
8 T
OSC
16 T
OSC
32 T
OSC
64 T
OSC
RC
(1)
000
100
001
101
010
110
x11
2.50 MHz
5.00 MHz
10.00 MHz
20.00 MHz
40.00 MHz
48.00 MHz
1.00 MHz
(2)
Note 1:
The RC source has a typical T
AD
time of 2.5
μ
s.
For device frequencies above 1 MHz, the device must be in Sleep for the entire conversion or a F
OSC
divider should be used instead; otherwise, the A/D accuracy specification may not be met.
2:
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC18F4553-I/ML 功能描述:8位微控制器 -MCU 32KB FLSH 2048 RAM FSUSB 2.0 12B ADC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC18F4553-I/P 功能描述:8位微控制器 -MCU 32KB FLSH 2048 RAM FSUSB 2.0 12B ADC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC18F4553-I/P 制造商:Microchip Technology Inc 功能描述:8-Bit Microcontroller IC
PIC18F4553-I/PT 功能描述:8位微控制器 -MCU 32KB FLSH 2048 RAM FSUSB 2.0 12B ADC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC18F4553T-I/ML 功能描述:8位微控制器 -MCU 32KB FLSH 2048 RAM FSUSB 2.0 12B ADC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
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