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參數(shù)資料
| 型號： | AD693AD |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 2/12頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC SGNL COND 4-20MA TX 20-CDIP |
| 標準包裝： | 19 |
| 類型： | 信號調(diào)節(jié)器 |
| 輸入類型： | 電壓 |
| 輸出類型： | 電壓 |
| 接口： | 3 線 |
| 電流 - 電源： | 20mA |
| 安裝類型： | 通孔 |
| 封裝/外殼： | 20-CDIP（0.300"，7.62mm） |
| 供應(yīng)商設(shè)備封裝： | 20-CDIP |
| 包裝： | 管件 |
| 產(chǎn)品目錄頁面： | 798 (CN2011-ZH PDF) |
AD693
REV. A
–10–
increasing the application voltages by adding resistance between
Pins 14 and 3 will decrease the temperature span.
An external voltage divider may also be used in conjunction
with the circuit shown to produce any range of temperature
spans as well as providing zero output (4 mA) for a non 0
temperature input. For example, measuring VX with respect to a
voltage 2.385 times the excitation (rather than 2 times) will
result in zero input to the Signal Amplifier when the RTD is at
100
°C (or 138.5 ).
As suggested in Table I, the temperature span may also be adjusted
by changing the voltage span of the Signal Amplifier. Changing the
gain from 2 to 4, for example, will halve the temperature span to
about 52
°C on the 4-20mA output configuration. (See section
“Adjusting Input Span.”)
The configuration for a three-wire RTD shown in Figure 17 can
accommodate two-wire sensors by simply joining Pins 1 and 5
of the AD693.
INTERFACING LOAD CELLS AND METAL FOIL STRAIN
GAGES
The availability of the on-chip Voltage Reference, Auxiliary
Amplifier and 3 mA of excitation current make it easy to adapt
the AD693 to a variety of load cells and strain gages.
The circuit shown in Figure 18 illustrates a generalized approach in
which the full flexibility of the AD693 is required to interface to a
low resistance bridge. For a high impedance transducer the
bridge can be directly powered from the 6.2 V Reference.
Component values in this example have been selected to match
the popular standard of 2 mV/V sensitivity and 350
bridge
resistance. Load cells are generally made for either tension and
compression, or compression only; use of the 12 mA zero tap
allows for operation in the tension and compression mode. An
optional zero adjustment is provided with values selected for
+2% FS adjustment range.
Because of the low resistance of most foil bridges, the excitation
voltage must be low so as not to exceed the available 4 mA zero
current. About 1 V is derived from the 6.2 V Reference and an
external voltage divider; the Aux-Amp is then used as a follower
to make a stiff drive for the bridge. Similar applications with
higher resistance sensors can use proportionally higher voltage.
Finally, to accommodate the 2 mV/V sensitivity of the bridge,
the full-scale span of the Signal Amplifier must be reduced.
Using the load cell in both tension and compression with 1 V of
excitation, therefore, dictates that the span be adjusted to 4 mV.
By substituting in the expression, RS1 = 400 /[(30 mV/S) – 1],
the nominal resistance required to achieve this span is found to
be 61.54
. Calculate the minimum resistance required by
subtracting 10% from 61.54
to allow for the internal resistor
tolerance of the AD693, leaving 55.38
(See “Adjusting Input
Span.”) The standard value of 54.9
is used with a 20
potentiometer for full-scale adjustment.
If a load cell with a precalibrated sensitivity constant is to be
used, the resultant full-scale span applied to the Signal Amplifier is
found by multiplying that sensitivity by the excitation voltage.
(In Figure 18, the excitation voltage is actually (10 k
/62.3 k)
(6.2 V) = 0.995 V).
THERMOCOUPLE MEASUREMENTS
The AD693 can be used with several types of thermocouple
inputs to provide a 4-20 mA current loop output corresponding
to a variety of measurement temperature ranges. Cold junction
compensation (CJC) can be implemented using an AD592 or
AD590 and a few external resistors as shown in Figure 19.
From Table II simply choose the type of thermocouple and the
appropriate average reference junction temperature to select
values for RCOMP and RZ. The CJC voltage is developed across
RCOMP as a result of the AD592 1
A/K output and is added to
the thermocouple loop voltage. The 50
potentiometer is
biased by RZ to provide the correct zero adjustment range
appropriate for the divider and also translates the Kelvin scale of
the AD592 to
°Celsius. To calibrate the circuit, put the
thermocouple in an ice bath (or use a thermocouple simulator
set to 0) and adjust the potentiometer for a 4 mA loop current.
The span of the circuit in
°C is determined by matching the
signal amplifier input voltage range to its temperature equivalent
Figure 18. Utilizing the Auxiliary Amplifier to Drive a Load Cell, 12 mA
± 8 mA Output
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| AD693AE | 功能描述:IC SGNL COND 4-20MA TX 20-CLCC RoHS:否 類別:集成電路 (IC) >> 接口 - 傳感器和探測器接口 系列:- 其它有關(guān)文件:Automotive Product Guide 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:74 系列:- 類型:觸控式傳感器 輸入類型:數(shù)字 輸出類型:數(shù)字 接口:JTAG，串行 電流 - 電源:100µA 安裝類型:表面貼裝 封裝/外殼:20-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:20-TSSOP 包裝:管件 |
| AD693AQ | 功能描述:IC TRANSMITTER 4-20MA 20-CDIP RoHS:否 類別:集成電路 (IC) >> 接口 - 傳感器和探測器接口 系列:- 其它有關(guān)文件:Automotive Product Guide 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:74 系列:- 類型:觸控式傳感器 輸入類型:數(shù)字 輸出類型:數(shù)字 接口:JTAG，串行 電流 - 電源:100µA 安裝類型:表面貼裝 封裝/外殼:20-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:20-TSSOP 包裝:管件 |
| AD693BQ | 制造商:AD 制造商全稱:Analog Devices 功能描述:Loop-Powered 4a??20 mA Sensor Transmitter |
| AD694 | 制造商:AD 制造商全稱:Analog Devices 功能描述:4.20 mA Transmitter |
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