поискавой системы для электроныых деталей
  Russian  ▼
ALLDATASHEETRU.COM

X  

AD7984 датащи(PDF) 2 Page - Analog Devices

номер детали AD7984
подробное описание детали  Devices Connected
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
производитель  AD [Analog Devices]
домашняя страница  http://www.analog.com
Logo AD - Analog Devices

AD7984 датащи(HTML) 2 Page - Analog Devices

  AD7984 Datasheet HTML 1Page - Analog Devices AD7984 Datasheet HTML 2Page - Analog Devices AD7984 Datasheet HTML 3Page - Analog Devices AD7984 Datasheet HTML 4Page - Analog Devices AD7984 Datasheet HTML 5Page - Analog Devices AD7984 Datasheet HTML 6Page - Analog Devices AD7984 Datasheet HTML 7Page - Analog Devices AD7984 Datasheet HTML 8Page - Analog Devices AD7984 Datasheet HTML 9Page - Analog Devices Next Button
Zoom Inzoom in Zoom Outzoom out
 2 / 12 page
background image
CN-0269
Circuit Note
Rev. 0 | Page 2 of 12
This circuit is an ideal solution for a multichannel data
acquisition card for many industrial applications including
process control, and power line monitoring.
CIRCUIT DESCRIPTION
The circuit shown in Figure 1 is a classic multichannel non-
synchronous data acquisition signal chain consisting of a
multiplexer, amplifiers, and an ADC.
The architecture allows fast sampling of multiple channels using
a single ADC, providing low cost and excellent channel-to-
channel matching.
Channel-to-channel switching speed is limited by the settling
time of the various components following the multiplexer in the
signal chain, because the multiplexer can present a full-scale
step voltage output to the downstream amplifier and ADC. The
components in this circuit have been specifically chosen to
minimize the settling time and maximize channel-to-channel
switching speed.
Component Selection
The ADG5208 multiplexer switches one of eight inputs to a
common output, as determined by the 3-bit binary address
lines. The ADG5236 contains two independently selectable
single-pole/double throw (SPDT) switches. Two ADG5208
switches, combined with one ADG5236, allow 16 single-ended
channels or 8 true differential channels to be connected to the
rest of the signal chain using a 4-bit digital control signal.
The 4-bit digital signal is generated by a 4-bit binary up/down
counter triggered by the same signal used for the convert (CNV)
input to the 18-bit, 1.33 MSPS AD7984 ADC.
The AD8065 JFET input op amp has a 145 MHz bandwidth and
is configured as a unity-gain buffer to provide excellent settling
time performance and extremely high input impedance. The
AD8065 also provides very low impedance output to drive the
AD8475 funnel amp attenuation stage.
The advantages of fully differential signal chain are good
common-mode rejection and reduction in second-order
distortion products. In order to process ±10 V industrial level
signals by modern low voltage differential input ADCs, the
attenuation and level shifting stage is necessary.
The AD8475, fully differential, attenuating (funnel) amplifier with
integrated precision gain resistors provides precision attenuation
(by 0.4× or 0.8×), common-mode level shifting, and single-
ended-to-differential conversion along with input overvoltage
protection. Fast settling time (50 ns to 0.001%), and low noise
performance (10 nV/√Hz) make the AD8475 well suited to drive
18-bit differential input ADCs at sampling rates up to 4 MSPS.
The AD7984, 18-bit, PulSAR® ADC selected in this circuit
provides 18-bit resolution at 1.33 MSPS when sampling a single
channel. However, the settling time of various components in
the signal chain limit the overall accuracy when sequentially
switching between channels. For example, 16-bit performance is
achieved when switching between channels at a 250 kHz rate.
Timing Analysis
When the circuit shown in Figure 1 is operating in the continuous
switching mode, all the 16-channel signal-ended or 8-channel
differential signal streams are merged into a time-division
multiplexed signal by the two stage multiplexer comprised of
the ADG5208 and the ADG5236. The multiplexed signal drives
the buffer circuit (AD8065) and the attenuation and level shift
circuit (AD8475). The output signal of the AD8475 drives the
differential input ADC through an RC filter (2.2 nF, 10 Ω).
The multiplexed input signal typically consists of large voltage
steps when switching between channels. In the worst case, one
channel is at negative full scale, while the next channel is at
positive full scale. Therefore, the step can be as large as the full
range of input signal, in this case, 20 V. It is a tremendous challenge
for the analog signal chain to settle to high precision from such
a large step signal level in a short time. The timing of the circuit
must be carefully examined to determine the amount of settling
time available at various sampling rates and the settling time
required by the circuits in the signal chain.
Figure 2 shows the basic timing diagram of the system, and this
is where the analysis starts.
Figure 2. Multichannel Data Acquisition Circuit Timing
ACQUISITION
[0000]
[0001]
SETTLING TO CH0
SETTLING TO CH1
CONVERSION
tCONV
tACQ
ACQUISITION
tS
tMD
tDD
tSETTLE
CNV
STATUS
[CH3 TO CH0]
VOUT_SW


Аналогичный номер детали - AD7984

производительномер деталидатащиподробное описание детали
logo
Analog Devices
AD7984 AD-AD7984 Datasheet
722Kb / 24P
   18-Bit, 1.33 MSPS PulSAR 10.5 mW ADC in MSOP/QFN
REV. 0
AD7984 AD-AD7984 Datasheet
469Kb / 24P
   16-Bit Lower Power
REV. B
AD7984 AD-AD7984 Datasheet
926Kb / 32P
   Ultralow Power, Low Distortion
REV. B
AD7984 AD-AD7984 Datasheet
814Kb / 24P
   18-Bit, 5 MSPS PulSAR Differential ADC
REV. 0
AD7984 AD-AD7984 Datasheet
554Kb / 24P
   Precision, Selectable Gain, Fully Differential Funnel Amplifier
REV. B
More results

Аналогичное описание - AD7984

производительномер деталидатащиподробное описание детали
logo
Analog Devices
CN0221 AD-CN0221 Datasheet
418Kb / 5P
   Devices Connected
CN0216 AD-CN0216 Datasheet
603Kb / 5P
   Devices Connected
CN0385 AD-CN0385 Datasheet
532Kb / 13P
   Devices Connected
CN0253 AD-CN0253 Datasheet
135Kb / 4P
   Devices Connected
CN0357 AD-CN0357 Datasheet
223Kb / 5P
   Devices Connected
CN0388 AD-CN0388 Datasheet
503Kb / 5P
   Devices Connected
CN0267 AD-CN0267 Datasheet
336Kb / 8P
   Devices Connected
CN0287 AD-CN0287 Datasheet
476Kb / 9P
   Devices Connected
CN0326 AD-CN0326 Datasheet
519Kb / 7P
   Devices Connected
CN0336 AD-CN0336 Datasheet
301Kb / 7P
   Devices Connected
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12


датащи скачать

Go To PDF Page


ссылки URL




Конфиденциальность
ALLDATASHEETRU.COM
Вашему бизинису помогли Аллдатащит?  [ DONATE ] 

Что такое Аллдатащит   |   реклама   |   контакт   |   Конфиденциальность   |   обмен ссыками   |   поиск по производителю
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com