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參數(shù)資料
| 型號(hào)： | XTR104AP |
| 英文描述： | 4-20mA Current Transmitter with BRIDGE EXCITATION AND LINEARIZATION |
| 中文描述： | 4 - 20mA電流變送器的電橋的激勵(lì)和線性化 |
| 文件頁(yè)數(shù)： | 6/11頁(yè) |
| 文件大小： | 165K |
| 代理商： | XTR104AP |
6
XTR104
APPLICATION INFORMATION
Figure 1 shows the basic connection diagram for the XTR104.
The loop power supply, V
PS
, provides power for all cir-
cuitry. Loop current is measured as a voltage across the
series load resistor, R
L
.
A high impedance (
≥
2750
) strain gage sensor can be
excited directly by the 5V reference output terminal, V
R
.
The output terminals of the bridge are connected to the
instrumentation amplifier inputs, V
+IN
and V
–IN
. The resis-
tor, R
G
, sets the gain of the instrumentation amplifier as
required by the full-scale bridge voltage, V
FS
.
The transfer function is:
I
O
= V
IN
(0.016 + 40/R
G
) + 4mA,
Where: V
IN
is the voltage applied to the V
+IN
and
V
–IN
differential inputs (in Volts.) R
G
in
.
With no R
G
connected (R
G
=
∞
), a 0V to 1V input produces
a 4 to 20mA output current. With R
G
= 25
, a 0V to 10mV
input produces a 4 to 20mA output current. Other values for
R
G
can be calculated as follows:
2500
1
V
FS
Where: V
FS
is the full scale voltage applied to the V
+IN
and
V
–IN
differential inputs (in Volts).
R
G
in
.
Under-scale input voltage (negative) will cause the output
current to decrease below 4mA. Increasingly negative input
will cause the output current to limit at approximately
3.6mA.
Increasingly positive input voltage (above V
FS
) will produce
increasing output current according to the transfer function,
up to the output current limit of approximately 34mA.
EXTERNAL TRANSISTOR
Transistor Q
1
conducts the majority of the signal-dependent
4 to 20mA loop current. Using an external transistor isolates
the power dissipation from the precision input and reference
circuitry of the XTR104, maintaining excellent accuracy.
Since the external transistor is inside a feedback loop its
characteristics are not critical. Many common NPN types
can be used. Requirements for operation at the full loop
supply voltage are: V
CEO
= 45V min,
β
= 40 min and P
D
=
800mW. Power dissipation requirements may be lower if the
maximum loop power supply voltage is less than 40V. Some
possible choices for Q
1
are listed in Figure 1.
LOOP POWER SUPPLY
The voltage applied to the XTR104, V+, is measured with
respect to the I
O
connection, pin 7. V+ can range from 9V to
40V. The loop supply voltage, V
PS
, will differ from the
voltage applied to the XTR104 according to the voltage drop
on the current sensing resistor, R
L
(plus any other voltage
drop in the line).
If a low loop supply voltage is used, R
L
must be made a
relatively low value to assure that V+ remains 9V or greater
for the maximum loop current of 20mA. It may, in fact, be
prudent to design for V+ equal or greater than 9V with loop
currents up to 34mA to allow for out-of-range input condi-
tions. The typical performance curve “Loop Resistance vs
Loop Power Supply” shows the allowable sense resistor
values for full-scale 20mA.
The low operating voltage (9V) of the XTR104 allows
operation directly from personal computer power supplies
(12V
±
5%). When used with the RCV420 Current Loop
Receiver (see Figure 9), load resistor voltage drop is only
1.5V at 20mA.
(2)
(1)
R
G
=
– 1
FIGURE 1. Bridge Sensor Application, Connected for Positive Nonlinearity.
XTR104
R
G
–
+
(1)
R
L
–
V
PS
–
+
11
0.01μF
+
13
7
(3)
4
6
5
1
(3)
12
10
2
R
B
(2)
3
R
LIN(3)
8
9
V
+
LIN
R
G
V
–
LIN
V
+
IN
R
G
V
–
IN
I
O
E
B
V+
R
LIN
R
G
= 1
V
FS
where V
FS
is Full Scale V
IN
.
2500
– 1
(1)
(2) R
≥
2750
.
Otherwise add series resistance (see Figure 8).
(3) See text — “Linearization”.
Bridge Sensor
R
2
R
1
V
R
I
O
= 4-20mA
4-20mA
Q
1
Possible choices for Q
1
(see text).
Type Package
2N4922
TIP29B
TIP31B
TO-225
TO-220
TO-220
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| XTR104AU | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:100SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:20-DIP; DNL +/-:0.5LSB; Leaded Process Compatible:No; No. of Bits:16 RoHS Compliant: No |
| XTR104BP | 4-20mA Current Transmitter with BRIDGE EXCITATION AND LINEARIZATION |
| XTR104BU | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:100SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:20-SOIC; DNL +/-:0.5LSB; Leaded Process Compatible:No; No. of Bits:16 RoHS Compliant: No |
| XTR106 | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:212SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:8-SOIC; Leaded Process Compatible:No; No. of Bits:18 RoHS Compliant: Yes |
| XTR106P | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:100SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:8-SOIC; Leaded Process Compatible:No; No. of Bits:18 RoHS Compliant: Yes |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| XTR104AU | 制造商:Rochester Electronics LLC 功能描述:4-20 MA XMITTER - Bulk |
| XTR104BP | 制造商:Texas Instruments 功能描述:IC 4-20 MA I-TRANSMITTER 16-DIP |
| XTR104BU | 制造商:Texas Instruments 功能描述: |
| XTR105 | 制造商:BB 制造商全稱:BB 功能描述:4-20mA CURRENT TRANSMITTER with Sensor Excitation and Linearization |
| XTR105-DIE | 制造商:TI 制造商全稱:Texas Instruments 功能描述:4-20mA CURRENT TRANSMITTER WITH SENSOR EXCITATION AND LINEARIZATION |
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