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PDF IXR100 Data sheet ( Hoja de datos )
| Número de pieza | IXR100 | |
| Descripción | Isolated / Self-Powered / Temperature Sensor Conditioning 4-20mA TWO-WIRE TRANSMITTER | |
| Fabricantes | Burr-Brown Corporation | |
| Logotipo |  |
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www.DataSheet4U.com
® IXR100
Isolated, Self-Powered,
Temperature Sensor Conditioning
4-20mA TWO-WIRE TRANSMITTER
FEATURES
q 1500Vrms ISOLATION
q TRUE TWO-WIRE OPERATION :
Power and Signal on One Wire Pair
q RESISTANCE OR VOLTAGE INPUT
q DUAL MATCHED CURRENT SOURCES:
400µA at 7V
q WIDE SUPPLY RANGE 12V TO 36V
q PT100 RTD LINEARIZATION
DESCRIPTION
The IXR100 is an isolated 2-wire transmitter featuring
loop powered operation and resistive temperature
sensor conditioning (excitation and linearization).
It contains a DC/DC convertor, high accuracy instru-
mentation amplifier with single resistor programmable
span and linearization, and dual matched excitation
current sources. This combination is ideally suited
to a range of transducers such as thermocouples,
RTDs, thermistors and strain gages. The small size
makes it ideal for use in head mounted isolated tem-
perature transmitters as well as rack and rail mounted
equipment.
Pt100 NONLINEARITY CORRECTION
USING IXR100
4.4
Uncorrected
APPLICATIONS
q INDUSTRIAL PROCESS CONTROL:
All Types of Isolated Transmitters;
Pt100 RTD
Thermocouple Inputs
Current Shunt (mV) Inputs
q ISOLATED DUAL CURRENT SOURCES
q AUTOMATED MANUFACTURING
q POWER PLANT/ENERGY MONITORING
q GROUND LOOP ELIMINATION
The isolated two-wire transmitter allows signal trans-
mission and device power to be supplied on a single
wire-pair by modulating the power supply current
with the isolated signal source. The transmitter is
resistant to voltage drops from long runs and noise
from motors, relays, actuators, switches, transformers
and industrial equipment.
It can be used by OEMs producing isolated transmitter
modules or by data acquisition system manufacturers.
The IXR100 is also useful for general purpose isolated
current transmission where the elimination of ground
loops is important.
+VIN
0.4mA
0.4mA
4
2 + +IR
6
RS
Optional
Offset
RO Adjust
1 10
IR
11
RO RORO12
4-20mA
28
VS
+0.1
–0.1
–200
Corrected
Process Temperature (°C)
RTD
850
RS IXR100
–VIN
RZ
7 RS
3
– RLIN
Com
RLIN
5
9
8
RLIN
RCM
0.01µF
18
+ VOUT
RL
–
International Airport Industrial Park • Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706
Tel: (520) 746-1111 • Twx: 910-952-1111 • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
©1992 Burr-Brown Corporation
PDS-1141A
Printed in U.S.A. August, 1993
1 page  
RL1, RL2
The resistor connected between these terminals determines
the gain of the linearization circuit and the amount of
correction applied to the RTD. Its value may be determined
in several ways. Two of which are shown as follows.
1. Empirically by interactively adjusting RLIN, RS and RZ to
achieve best fit 4 to 20mA output. RZ is used to set 4mA
at minimum input, RS is adjusted for 12mA with a half
span input, and RLIN is adjusted to give 20mA with a full
span input. This may require a few iterations but is
probably the most practical method for field calibration.
RLIN will range between 500Ω and 1500Ω for 100Ω
sensors (Pt100, D100, SAMA). Initially it may seem a
little strange adjusting RS for 12mA and RLIN for 20mA.
However, convergence is achieved much more quickly as
the linearized curve passes through zero and has less
effect at the mid span and the linearity trim resistor tends
to adjust the transfer function more at the full span than
the mid point.
2. Using Table I and linear interpolation for values of span
not given in the table. This will yield very accurate results
for the Pt100 sensor and acceptable results for D100 and
SAMA sensors.
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–
IXR100
+ 12
10
10kΩ
11
(a)
±400µA adjust range
–
IXR100
ZERO ADJUST (OPTIONAL) OS1, OS2, OS3
The IXR100 has provision for adjusting the output offset
current as shown in Figure 2. In many applications the
already low offset will not need to be known at all. This trim
effects the V/I converter stage and does not introduce VOS
drift errors that occur when the trim is performed at the input
stage. If possible use RZ to trim sensor output error to zero
and use the offset control to trim the output to 4mA when
VIN = 0V. The offset adjustment can be made with a
+ 12
10
5kΩ
11
(b)
5kΩ
±40µA adjust range
FIGURE 2. Basic Connection for Zero Adjust.
SPAN ∆T (°C)
TMIN (°C)
–200
–150
–100
–50
50
573
745
983
1233
100
653
855
1105
1284
200
839
1059
1228
1286
300
995
1158
1251
1262
400
1083
1197
1249
1236
500
1131
1206
1231
1208
600
1152
1205
1207
1180
700
1159
1196
1182
1152
800
1159
1175
1156
1125
900
1154
1151
1129
1097
1000
1140
1127
0 1302 1287 1273 1229 1201 1173 1145 1117 1089
50 1263 1249 1220 1192 1164 1136 1108 1081 1054
100 1225 1211 1183 1155 1127 1100 1073 1046
150 1188 1174 1146 1119 1091 1064 1038 1011
200 1151 1137 1110 1083 1056 1030 1003
250 1114 1101 1074 1048 1021 995 969
300 1079 1066 1039 1013 987 962
350 1044 1031 1005 979 954 928
400 1009 996 971 946 921
450 975 963 938 913 888
500 942 930 905 881
550 909 897 873 849 NOTES: (1) Linear interpolation between two horizontal
600 877 865 841
or vertical values yields acceptable values. (2) Although
650 845 834 810
not optimum, these values will also yield acceptable
700 814 803
results with D100 and SAMA 100Ω nominal sensors.
750 784 773
(3) Double RLIN value for PT200.
800 754
TABLE I. RLIN Values for Pt100 Sensor.
5
IXR100
®
5 Page 
∆VD/∆T = –2mV/°C. R5 and R6 form a voltage divider for
the diode voltage VD. The divider values are selected so that
the gradient ∆VD/∆T equals the gradient of the thermo-
couple at the reference temperature. At +25°C this is
approximately –52µV/°C (obtained from standard thermo-
couple table); therefore,
∆VTC/∆T = (∆VD/∆T)(R6/(R5 + R6))
(2)
–52µV/°C = (–2000µV/°C)(R6/(R5+R6 ))
R5 is chosen as 3.74kΩ to be much larger than the resistance
of the diode. Solving for R6 yields 100Ω.
Transmit 4mA for Tl = 0°C and 20mA for Tl = +1000°C.
Note: VlN = VIN+ – VIN– indicates that Tl is relative to T2.
The input full scale span is 58mV. RS is found from
Equation (1) and equals 153.9Ω.
R4 is chosen to make the output 4mA at TTC = 0°C (VTC =
1.28mV) and TD = 25°C (VD = 0.6V).
VTC will be –1.28mV when TTC = 0°C and the reference
junction is at +25°C. V4 must be computed for TD = +25°C
to make VIN = 0V.
VD(25°C) = 600mV
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VIN(25°C) = 600mV (100/3740) = 16.0mV
VIN = VIN+ – VIN– = VTC + V4 – VIN–
With VIN = 0 and VTC = –1.28mV,
V4 = VIN+ – VTC
V4 = 16.0mV – (–1.28mV)
0.4mA (R4) = 17.28mV
R4 = 43.2Ω
THERMOCOUPLE BURN-OUT INDICATION
In process control applications it is desirable to detect when
a thermocouple has burned out. This is typically done by
forcing the two-wire transmitter current to the upper or
lower limit when the thermocouple impedance goes very
high. The circuits of Figures 10, 11 and 12 inherently have
down scale indication. When the impedance of the thermo-
couple gets very large (open) the bias current flowing into
the + input (large impedance) will cause IO to go to its lower
range limit value (about 3.6mA). If up scale indication is
desired, the circuit of Figure 13 should be used. When the TC
opens, the output will go to its upper range limit value (about
32mA or higher).
0.4mA 0.4mA
–
VIN
+
1
3
–
4
7
RS
6
IXR100
2+
5
RZ RTD
RCM
0.01µF
FIGURE 9. Pt100 RTD Without Linearization.
D1
28 1N4148
18
+VS
4-20mA
VOUT
+
RL
–
®
11 IXR100
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet IXR100.PDF ] | |
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