TEXAS INSTRUMENTS XTR112, XTR1144 Technical data

®

XTR114

XTR112

XTR112

4-20mA CURRENT TRANSMITTERS

with Sensor Excitation and Linearization

FEATURES

● LOW UNADJUSTED ERROR

● PRECISION CURRENT SOURCES

XTR112: Two 250µA
XTR114: Two 100µA

● RTD OR BRIDGE EXCITATION

● LINEARIZATION

● TWO OR THREE-WIRE RTD OPERATION

● LOW OFFSET DRIFT: 0.4µV/°C

● LOW OUTPUT CURRENT NOISE: 30nAp-p

● HIGH PSR: 110dB min

● HIGH CMR: 86dB min

● WIDE SUPPLY RANGE: 7.5V TO 36V

● SO-14 SOIC PACKAGE

XTR114

APPLICATIONS

● INDUSTRIAL PROCESS CONTROL

● FACTORY AUTOMATION

● SCADA REMOTE DATA ACQUISITION

● REMOTE TEMPERATURE AND PRESSURE

TRANSDUCERS

Pt1000 NONLINEARITY CORRECTION

5

4

3

2

USING XTR112 and XTR114

Uncorrected

RTD Nonlinearity

SBOS101

DESCRIPTION

The XTR112 and XTR114 are monolithic 4-20mA,
two-wire current transmitters. They provide complete
current excitation for high impedance platinum RTD
temperature sensors and bridges, instrumentation am­plifier, and current output circuitry on a single inte-

1

Nonlinearity (%)

0

–1

–200°C

Process Temperature (°C)

Corrected

Nonlinearity

+850°C

grated circuit. The XTR112 has two 250µA current
sources while the XTR114 has two 100µA sources for
RTD excitation.

Versatile linearization circuitry provides a 2nd-order
correction to the RTD, typically achieving a 40:1
improvement in linearity.

I

R

I

R

V

LIN

V

+

REG

7.5V to 36V

Instrumentation amplifier gain can be configured for a

= 100µA

R

4-20 mA

wide range of temperature or pressure measurements.
Total unadjusted error of the complete current trans­mitter is low enough to permit use without adjustment
in many applications. This includes zero output cur­rent drift, span drift and nonlinearity. The XTR112
and XTR114 operate on loop power supply voltages
down to 7.5V.

Both are available in an SO-14 surface-mount pack-

RTD

R

G

XTR112
XTR114

–

XTR112: IR = 250µA
XTR114: I

age and are specified for the –40°C to +85°C indus­trial temperature range.

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: [phone]

Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: [phone] • Immediate Product Info: [phone]

©

1998 Burr-Brown Corporation PDS-1473A Printed in U.S.A. December, 1998

1

XTR112, XTR114

V

PS

V

O

R

L

®

SPECIFICATIONS

At TA = +25°C, V+ = 24V, and TIP29C external transistor, unless otherwise noted.

XTR112U XTR112UA

XTR114U XTR114UA
PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
OUTPUT

Output Current Equation A
Output Current, Specified Range 4 20 ✻✻mA

Over-Scale Limit 24 27 30 ✻✻✻ mA
Under-Scale Limit: XTR112 I

XTR114 0.6 1 1.4 ✻✻✻ mA

ZERO OUTPUT

(1)

= 0 0.9 1.3 1.7 ✻✻✻ mA

REG

VIN = 0V, RG = ∞ 4 ✻ mA

Initial Error ±5 ±25 ✻ ±50 µA

vs Temperature ±0.07 ±0.5 ✻ ±0.9 µA/°C
vs Supply Voltage, V+ V+ = 7.5V to 36V 0.04 0.2 ✻✻ µA/V
vs Common-Mode Voltage
vs V

Output Current 0.3 ✻ µA/mA

REG

Noise: 0.1Hz to 10Hz 0.03 ✻ µAp-p

VCM = 1.25V to 3.5V

(2)

SPAN

Span Equation (transconductance)
Initial Error

Nonlinearity: Ideal Input

INPUT

(3)

vs Temperature

(5)

(3)

(4)

Full Scale (VIN) = 50mV ±0.05 ±0.2 ✻ ±0.4 %

Full Scale (VIN) = 50mV 0.003 0.01 ✻✻ %

Offset Voltage VCM = 2V ±50 ±100 ✻ ±250 µV

vs Temperature ±0.4 ±1.5 ✻ ±3 µV/°C
vs Supply Voltage, V+ V+ = 7.5V to 36V ±0.3 ±3 ✻✻ µV/V
vs Common-Mode Voltage, V

RTI (CMRR)

Common-Mode Input Range

(2)

= 1.25V to 3.5V

CM

(2)

Input Bias Current 525 ✻ 50 nA

vs Temperature 20 ✻ pA/°C

Input Offset Current ±0.2 ±3 ✻ ±10 nA

vs Temperature 5 ✻ pA/°C

Impedance: Differential 0.1 || 1 ✻ GΩ || pF

Common-Mode 5 || 10 ✻ GΩ || pF

Noise: 0.1Hz to 10Hz 0.6 ✻ µVp-p
CURRENT SOURCES V

Current: XTR112 250 ✻ µA

= 2V

O

(6)

XTR114 100 ✻ µA

Accuracy ±0.05 ±0.2 ✻ ±0.4 %

vs Temperature ±15 ±35 ✻ ±75 ppm/°C
vs Power Supply, V+ V+ = 7.5V to 36V ±10 ±25 ✻✻ ppm/V

Matching ±0.02 ±0.1 ✻ ±0.2 %

vs Temperature ±3 ±15 ✻ ±30 ppm/°C
vs Power Supply, V+ V+ = 7.5V to 36V 1 10 ✻✻ ppm/V

Compliance Voltage, Positive (V+) –3

Negative

(2)

Output Impedance: XTR112 500 ✻ MΩ

XTR114 1.2 ✻ GΩ

Noise: 0.1Hz to 10Hz: XTR112 0.001 ✻ µAp-p

XTR114 0.0004 ✻ µAp-p

(2)

V

REG

Accuracy ±0.02 ±0.1 ✻✻ V

vs Temperature ±0.2 ✻ mV/°C
vs Supply Voltage, V+ 1 ✻ mV/V

Output Current: XTR112 –1, +2.1 ✻ mA

XTR114 –1, +2.4 ✻ mA

Output Impedance 75 ✻ Ω

LINEARIZATION

R

(internal) 1 ✻ kΩ

LIN

Accuracy ±0.2 ±0.5 ✻ ±1%
vs Temperature ±25 ±100 ✻✻ ppm/°C

POWER SUPPLY

Specified Voltage +24 ✻ V
Operating Voltage Range +7.5 +36 ✻✻V

TEMPERATURE RANGE

Specification, T
Operating /Storage Range –55 +125 ✻✻°C
Thermal Resistance,

SO-14 Surface-Mount 100 ✻ °C/W

MIN

to T

MAX

θ

JA

✻ Specification same as XTR112U, XTR114U.
NOTES: (1) Describes accuracy of the 4mA low-scale offset current. Does not include input amplifier effects. Can be trimmed to zero. (2) Voltage measured with

respect to I
include Zero Output initial error. (6) Current source output voltage with respect to I

pin. (3) Does not include initial error or TCR of gain-setting resistor, RG. (4) Increasing the full-scale input range improves nonlinearity. (5) Does not

RET

®

XTR112, XTR114

IO = VIN • (40/RG) + 4mA, VIN in Volts, RG in Ω

0.02 ✻ µA/V

S = 40/R

G

✻ A/V

±3 ±25 ✻✻ ppm/°C

±10 ±50 ✻ ±100 µV/V

1.25 3.5 ✻✻V

(V+) –2.5

✻✻ V

0 –0.2 ✻✻ V

5.1 ✻ V

–40 +85 ✻✻°C

pin.

RET

2

PIN CONFIGURATION

Top View SO-14

XTR112 and XTR114

1

I

R1
–+

2

VIN

3

R

G

4

R

G

5

NC

6

I

RET

7

I

O

NC = No Connection

14
13
12
11
10

9
8

I

R2

V

IN

V

LIN

V

REG

V+
B (Base)
E (Emitter)

ABSOLUTE MAXIMUM RATINGS

Power Supply, V+ (referenced to IO pin).......................................... 40V

Input Voltage, V

Storage Temperature Range ....................................... –55°C to +125°C

Lead Temperature (soldering, 10s) .............................................. +300°C

Output Current Limit ............................................................... Continuous

Junction Temperature ................................................................... +165°C

NOTE: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods may degrade
device reliability.

+

–

, VIN (referenced to IO pin) ............................ 0V to V+

IN

(1)

ELECTROSTATIC
DISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.

ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.

PACKAGE/ORDERING INFORMATION

PRODUCT SOURCES PACKAGE NUMBER

CURRENT DRAWING TEMPERATURE ORDERING TRANSPORT

XTR112U 2 x 250µA SO-14 Surface Mount 235 –40°C to +85°C XTR112U Rails

" " " " " XTR112U/2K5 Tape and Reel

XTR112UA 2 x 250µA SO-14 Surface Mount 235 –40°C to +85°C XTR112UA Rails

" " " " " XTR112UA/2K5 Tape and Reel

XTR114U 2 x 100µA SO-14 Surface Mount 235 –40°C to +85°C XTR114U Rails

" " " " " XTR114U/2K5 Tape and Reel

XTR114UA 2 x 100µA SO-14 Surface Mount 235 –40°C to +85°C XTR114UA Rails

" " " " " XTR114UA/2K5 Tape and Reel

NOTES: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. (2) Models with a slash (/ ) are
available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of “XTR112UA/2K5” will get a single
2500-piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to Appendix B of Burr-Brown IC Data Book.

PACKAGE SPECIFIED

(1)

RANGE NUMBER

(2)

MEDIA

The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use
of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits
described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.

®

3

XTR112, XTR114

FUNCTIONAL BLOCK DIAGRAM

V

LIN

I

R1

12

13

+

V

IN

I

R2

1

14

I

R1

I

R2

V

REG

11

5.1V

V+

10

XTR112: I
XTR114: I

= I

= 250µA

R1

R2

= I

= 100µA

R1

R2

4

R

LIN

1kΩ

R

G

100µA

3

V

2

–

V

IN

I = 100µA +

IN

R

G

975Ω

25Ω

B

Q

9

1

E
8

7

IO = 4mA + V

IN

40

•

( )

R

G

6

I

RET

®

XTR112, XTR114

4

TYPICAL PERFORMANCE CURVES

10 100 1k 10k 100k

Frequency (Hz)

POWER-SUPPLY REJECTION RATIO vs FREQUENCY

1M

140

120

100

80

60

40

20

0

Power Supply Rejection Ratio (dB)

RG = 2kΩ

RG = 125Ω

At TA = +25°C, and V+ = 24V, unless otherwise noted.

50

40

30

20

10

Transconductance (20 Log mA/V)

0

100 1k 10k 100k

110
100

90
80
70
60
50
40
30

Common-Mode Rejection Ratio (dB)

20

10 100 1k 10k 100k

TRANSCONDUCTANCE vs FREQUENCY

RG = 500Ω

RG = 2kΩ

Frequency (Hz)

COMMON-MODE REJECTION RATIO vs FREQUENCY

R

G

RG = 2kΩ

Frequency (Hz)

RG = 125Ω

= 125Ω

1M

1M

STEP RESPONSE

RG = 2kΩ

20mA

RG = 125Ω

4mA/div

4mA

25µs/div

29

28

27

26

25

Over-Scale Current (mA)

24

23

OVER-SCALE CURRENT vs TEMPERATURE

V+ = 36V

–75 –50 –25 0 25 50 75 100

With External Transistor

V+ = 7.5V

V+ = 24V

Temperature (°C)

125

1.45

1.4

1.35

1.3

1.25

1.2

1.15

1.1

Under-Scale Current (mA)

1.05
1

0.95

5

UNDER-SCALE CURRENT vs TEMPERATURE

XTR112

XTR114

–75 –50 –25 0 25 50 75 100

Temperature (°C)

XTR112, XTR114

125

®

TYPICAL PERFORMANCE CURVES (CONT)

At TA = +25°C, and V+ = 24V, unless otherwise noted.

INPUT VOLTAGE AND CURRENT

10k

1k

100

Input Voltage Noise (nV/√Hz)

10

1 10 100 1k 10k

25

20

15

10

5

Input Bias and Offset Current (nA)

0

–75 –50 –25 0 25 50 75 100

NOISE DENSITY vs FREQUENCY

Current Noise

Voltage Noise

Frequency (Hz)

INPUT BIAS AND OFFSET CURRENT

vs TEMPERATURE

Temperature (°C)

ZERO OUTPUT AND REFERENCE

10k

1k

100

Input Current Noise (fA/√Hz)

10

100k

+I

B

–I

B

I

OS

125

10k

1k

100

Noise (pA/√Hz)

XTR114

10

1 10 100 1k 10k

4
2

0
–2
–4
–6
–8

Zero Output Current Error (µA)

–10
–12

–75 –50 –25 0 25 50 75 100

CURRENT NOISE vs FREQUENCY

Zero Output Current

XTR112

Reference Current

100k

Frequency (Hz)

ZERO OUTPUT CURRENT ERROR

vs TEMPERATURE

125

Temperature (°C)

80
70
60
50
40
30

Percent of Units (%)

20
10

0

0

0.2

0.4

®

XTR112, XTR114

INPUT OFFSET VOLTAGE DRIFT

PRODUCTION DISTRIBUTION

Typical production distribution

of packaged units. XTR112 and

XTR114 included.

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Input Offset Voltage Drift (µV/°C)

2.2

2.4

2.6

2.8

3.0

ZERO OUTPUT DRIFT

40
35
30
25
20
15

Percent of Units (%)

10

5

0

0

0.025

PRODUCTION DISTRIBUTION

Typical production distribution

0.05

0.075

0.1

0.2

0.15

0.125

0.175

0.225

Zero Output Drift (µA/°C)

of packaged units. XTR112

and XTR114 included.

0.25

0.3

0.275

0.35

0.325

0.4

0.375

0.425

0.45

0.5

0.475

6

TYPICAL PERFORMANCE CURVES (CONT)

Typical production distribution

of packaged units. XTR112 and

XTR114 included.

Current Source Matching Drift (ppm/°C)

CURRENT SOURCE MATCHING

DRIFT PRODUCTION DISTRIBUTION

90
80
70
60
50
40
30
20
10

0

Percent of Units (%)

0

2

4

6

8

1012141618202224262830

–1 –0.5 0 0.5 1 2.521.5

V

REG

Output Current (mA)

XTR112 V

REG

OUTPUT VOLTAGE

vs V

REG

OUTPUT CURRENT

3

5.35

5.30

5.25

5.20

5.15

5.10

5.05

5.00

V

REG

Output Voltage (V)

NOTE: Above 2.1mA,
zero output degrades

25°C

125°C

–55°C

At TA = +25°C, and V+ = 24V, unless otherwise noted.

CURRENT SOURCE DRIFT

40
35
30
25
20
15

Percent of Units (%)

10

5
0

0

PRODUCTION DISTRIBUTION

Typical production distribution

of packaged units.

XTR112 and XTR114 included.

5

10152025303540455055606570

Current Source Drift (ppm/°C)

75

XTR114 V

vs V

5.35

REG

125°C

5.30

5.25

5.20

25°C

5.15

Output Voltage (V)

–55°C

5.10

REG

V

5.05

5.00
–1 –0.5 0 0.5 1 2.521.5

V

REG

OUTPUT VOLTAGE

REG

OUTPUT CURRENT

NOTE: Above 2.4mA,
zero output degrades

Output Current (mA)

+0.05

0

–0.05

3

REFERENCE CURRENT ERROR

vs TEMPERATURE

–0.10

–0.15

Reference Current Error (%)

–0.20

–75 –50 –25 0 25 50 75 100 125

Temperature (°C)

7

®

XTR112, XTR114

APPLICATION INFORMATION

Figure 1 shows the basic connection diagram for the XTR112
and XTR114. The loop power supply, VPS, provides power
for all circuitry. Output loop current is measured as a voltage
across the series load resistor, RL.

Two matched current sources drive the RTD and zero­setting resistor, RZ. These current sources are 250µA for the
XTR112 and 100µA for the XTR114. Their instrumentation
amplifier input measures the voltage difference between the
RTD and RZ. The value of RZ is chosen to be equal to the
resistance of the RTD at the low-scale (minimum) measure­ment temperature. RZ can be adjusted to achieve 4mA output
at the minimum measurement temperature to correct for
input offset voltage and reference current mismatch of the
XTR112 and XTR114.

RCM provides an additional voltage drop to bias the inputs of
the XTR112 and XTR114 within their common-mode input
range. RCM should be bypassed with a 0.01µF capacitor to
minimize common-mode noise. Resistor RG sets the gain of
the instrumentation amplifier according to the desired tem­perature range. R
correction to the RTD, typically achieving a 40:1 improve­ment in linearity. An additional resistor is required for three­wire RTD connections, see Figure 3.

provides second-order linearization

LIN1

The transfer function through the complete instrumentation
amplifier and voltage-to-current converter is:

IO = 4mA + V

• (40/RG)

IN

(VIN in volts, RG in ohms)

where VIN is the differential input voltage. As evident from
the transfer function, if RG is not used the gain is zero and
the output is simply the XTR’s zero current. The value of R
varies slightly for two-wire RTD and three-wire RTD con­nections with linearization. RG can be calculated from the
equations given in Figure 1 (two-wire RTD connection) and
Table I (three-wire RTD connection).

The I
sources and V

pin is the return path for all current from the current

RET

REG

. The I

pin allows any current used in

RET

external circuitry to be sensed by the XTR112 and XTR114
and to be included in the output current without causing an
error.

The V

pin provides an on-chip voltage source of approxi-

REG

mately 5.1V and is suitable for powering external input
circuitry (refer to Figure 6). It is a moderately accurate
voltage reference—it is not the same reference used to set
the precision current references. V

is capable of sourcing

REG

approximately 2.1mA of current for the XTR112 and 2.4mA
for the XTR114. Exceeding these values may affect the 4mA
zero output. Both products can sink approximately 1mA.

G

RTD

I

R2

I

R1

12

1

V

LIN

13

+

V

IN

4

R

G

(2)

R

G

3

(3)

R

LIN1

(1)

R

Z

R

CM

0.01µF

R

G

–

V

2

IN

I

RET

6

I

R1

I

XTR112
XTR114

14

11

R2

V

REG

V+

I

O

7.5V to 36V

10

9

B

E

7

Q

1

8

I = 4mA + V

O

NOTES: (1) RZ = RTD resistance at minimum measured temperature.

Possible choices for Q

0.01µF

40

• ( )

IN

R

G

2.5 • I

(2)

RG =

(3)

=

R

LIN1

TYPE

2N4922
TIP29C
TIP31C

I

PACKAGE

TO-225
TO-220
TO-220

R

[R1(R2 + RZ) – 2(R2RZ)]

REF

R

2

0.4 • R

LIN(R2

(2R1 – R2 – RZ)

REF

1

4-20 mA

L

– R

1

– R1)

(see text).

I

O

V

O

+

V

PS

–

= RTD Resistance at (T

where R

1

= RTD Resistance at T

R

XTR112: I
XTR114: I

R1
R1

= I

R2

= I

R2

= 250µA, R
= 100µA, R

CM
CM

= 3.3kΩ
= 8.2kΩ

2

R

= 1kΩ (Internal)

LIN

= 0.25 for XTR112

I

REF

= 0.1 for XTR114

I

REF

FIGURE 1. Basic Two-Wire RTD Temperature Measurement Circuit with Linearization.

®

XTR112, XTR114

8

MIN

MAX

+ T

MAX

)/2

A negative input voltage, VIN, will cause the output current
to be less than 4mA. Increasingly negative VIN will cause the
output current to limit at approximately 1.3mA for the
XTR112 and 1mA for the XTR114. Refer to the typical
curve “Under-Scale Current vs Temperature.”

Increasingly positive input voltage (greater than the full­scale input) will produce increasing output current according
to the transfer function, up to the output current limit of
approximately 27mA. Refer to the typical curve “Over­Scale Current vs Temperature.”

EXTERNAL TRANSISTOR

Transistor Q1 conducts the majority of the signal-dependent
4-20mA loop current. Using an external transistor isolates
the majority of the power dissipation from the precision
input and reference circuitry of the XTR112 and XTR114,
maintaining excellent accuracy.

Since the external transistor is inside a feedback loop its
characteristics are not critical. Requirements are: V

CEO

=
45V min, β = 40 min and PD = 800mW. Power dissipation
requirements may be lower if the loop power supply voltage
is less than 36V. Some possible choices for Q1 are listed in
Figure 1.

The XTR112 and XTR114 can be operated without this
external transistor, however, accuracy will be somewhat
degraded due to the internal power dissipation. Operation
without Q1 is not recommended for extended temperature
ranges. A resistor (R = 3.3kΩ) connected between the I

RET

pin and the E (emitter) pin may be needed for operation
below 0°C without Q1 to guarantee the full 20mA full-scale
output, especially with V+ near 7.5V.

LOOP POWER SUPPLY

The voltage applied to the XTR112 and XTR114, V+, is
measured with respect to the IO connection, pin 7. V+ can

10

V+

8

E

I

RET

XTR112
XTR114

6

R

Q

= 3.3kΩ

I

O

7

0.01µF

For operation without external
transistor, connect a 3.3kΩ
resistor between pin 6 and
pin 8. See text for discussion
of performance.

FIGURE 2. Operation Without External Transistor.

range from 7.5V to 36V. The loop supply voltage, VPS, will
differ from the applied voltage according to the voltage drop
on the current sensing resistor, RL (plus any other voltage
drop in the line).

If a low loop supply voltage is used, RL (including the loop
wiring resistance) must be made a relatively low value to
assure that V+ remains 7.5V or greater for the maximum
loop current of 20mA:

RLmax =




20mA




–R

WIRING

(V+)–7.5V

It is recommended to design for V+ equal or greater than

7.5V with loop currents up to 30mA to allow for out-of­range input conditions.

The low operating voltage (7.5V) of the XTR112 and
XTR114 allow operation directly from personal computer
power supplies (12V ±5%). When used with the RCV420
Current Loop Receiver (Figure 7), load resistor voltage drop
is limited to 3V.

ADJUSTING INITIAL ERRORS

Many applications require adjustment of initial errors. Input
offset and reference current mismatch errors can be cor­rected by adjustment of the zero resistor, RZ. Adjusting the
gain-setting resistor, RG, corrects any errors associated with
gain.

TWO-WIRE AND THREE-WIRE RTD
CONNECTIONS

In Figure 1, the RTD can be located remotely simply by
extending the two connections to the RTD. With this remote
two-wire connection to the RTD, line resistance will intro­duce error. This error can be partially corrected by adjusting
the values of RZ, RG, and R

LIN1

.

A better method for remotely located RTDs is the three-wire
RTD connection shown in Figure 3. This circuit offers
improved accuracy. RZ’s current is routed through a third
wire to the RTD. Assuming line resistance is equal in RTD
lines 1 and 2, this produces a small common-mode voltage
which is rejected by the XTR112 and XTR114. A second
resistor, R

, is required for linearization.

LIN2

Note that although the two-wire and three-wire RTD con­nection circuits are very similar, the gain-setting resistor,
RG, has slightly different equations:

IRRR RR

•+

25 2

.()–()

R

Two-wire:

Three-wire:

=

G

R

=

G

where RZ = RTD resistance at T

R1 = RTD resistance at (T
R2 = RTD resistance at T
I

= 0.25 for XTR112

REF

I

= 0.1 for XTR114

REF

9

XTR112, XTR114

[]

REF Z Z

12 2

RR

–

21

IRRRR

•25

.(–)(–)

REF Z Z

21

RR

–

21

MIN

MIN

MAX

+ T

MAX

)/2

®

Table I summarizes the resistor equations for two-wire and
three-wire RTD connections. An example calculation is also
provided. To maintain good accuracy, at least 1% (or better)
resistors should be used for RG. Table II provides standard
1% RG values for a three-wire Pt1000 RTD connection with
linearization for the XTR112. Table III gives RG values for
the XTR114.

LINEARIZATION

RTD temperature sensors are inherently (but predictably)
nonlinear. With the addition of one or two external resistors,
R

LIN1

and R

, it is possible to compensate for most of this

LIN2

nonlinearity resulting in 40:1 improvement in linearity over
the uncompensated output.

TWO-WIRE

General Equations

XTR112 (I
(see Table II)

XTR114 (I
(see Table III)

= 0.25)

REF

= 0.1)

REF

R

G

I

• 2.5 [R1 (R2 + RZ) – 2 (R2RZ)]

REF

=

0.625 • [R1 (R2 + RZ) – 2 (R2RZ)]

=

=

0.25 • [R

1

(R

– R1)

2

(R

– R1)

2

(R2 + RZ) – 2 (R2RZ)]

(R

– R1)

2

0.4 • R

=

I

• (2R1 – R2 – RZ)

REF

1.6 • R

=

(2R

4 • R

=

(2R

R

LIN1

(R2 – R1)

LIN

(R2 – R1)

LIN

– R2 – RZ)

1

(R2 – R1)

LIN

– R2 – RZ)

1

where RZ = RTD resistance at the minimum measured temperature, T

R1 = RTD resistance at the midpoint measured temperature, T
R2 = RTD resistance at maximum measured temperature, T
R

= 1kΩ (internal)

LIN

MAX

R

G

• 2.5 (R2 – RZ) (R1 – RZ)]

I

REF

=

=

=

MIN

= (T

+ T

MID

MIN

(R

0.625 • (R
(R

0.25 • (R
(R

)/2

MAX

– R1)

2

– RZ) (R1 – RZ)]

2

– R1)

2

– RZ) (R1 – RZ)]

2

– R1)

2

THREE-WIRE

0.4 • R

=

I

• (2R1 – R2 – RZ)

REF

1.6 • R

=

(2R

4 • R

=

(2R

XTR112 RESISTOR EXAMPLE:

The measurement range is –100°C to +200°C for a 3-wire Pt100 RTD connection. Determine the values for RS, RG, R
from the chart or calculate the values according to the equations provided.

METHOD 1: TABLE LOOK UP

T

= –100°C and ∆T = 300°C (T

MIN

Using Table II the 1% values are:

R

= 604Ω R

Z

R

= 750Ω R

G

METHOD 2: CALCULATION
Step 1: Determine RZ, R1, and R2.

RZ is the RTD resistance at the minimum measured temperature, T
Using Equation (1) at right gives R

is the RTD resistance at the maximum measured temperature, T

R

2

Using Equation (2) at right gives R
R

is the RTD resistance at the midpoint measured temperature,

1

T

= (T

+ T

MID

MIN

Using Equation (2) at right gives R1 = 1194Ω.

Step 2: Calculate R

R

G

R

LIN1

R

LIN2

) /2 = (–100 + 200)/2 = 50°C. R1 is NOT the average of RZ and R2.

MAX

, R

, and R

G

LIN1

= 757Ω (1% value is 750Ω)

= 33.322kΩ (1% value is 33.2kΩ)
= 58.548kΩ (1% value is 59kΩ)

= +200°C),

MAX

= 33.2kΩ

LIN1

= 59kΩ

LIN2

= 602.5Ω (1% value is 604Ω).

Z

= 1758.4Ω.

2

using equations above.

LIN2

= –100°C.

MIN

= 200°C.

MAX

Calculation of Pt1000 Resistance Values

(according to DIN IEC 751)
Equation (1) Temperature range from –200°C to 0°C:

R

= 1000 [1 + 3.90802 • 10–3 • T – 0.5802 • 10–6 • T

(T)

– 4.27350 • 10

Equation (2) Temperature range from 0°C to +850°C:

R

= 1000 (1 + 3.90802 • 10–3 • T – 0.5802 • 10–6 • T2)

(T)

where: R

(T)

T is the temperature in °C.

NOTE: Most RTD manufacturers provide reference tables for
resistance values at various temperatures.

Resistor values for other RTD types (such as Pt2000) can be
calculated using the XTR resistor selection program in the
Applications Section on Burr-Brown’s web site (www.burr­brown.com)

–12

• (T – 100) • T3]

is the resistance in Ω at temperature T.

R

LIN1

(R2 – R1)

LIN

(R2 – R1)

LIN

– R2 – RZ)

1

(R2 – R1)

LIN

– R2 – RZ)

1

LIN1

, and R

R

LIN2

0.4 • (R

+ RG)(R2 – R1)

LIN

=

• (2R1 – R2 – RZ)

I

REF

1.6 • (R

+ RG)(R2 – R1)

LIN

=

=

LIN2

– R2 – RZ)

(2R

1

4 • (R

+ RG)(R2 – R1)

LIN

(2R

– R2 – RZ)

1

. Look up the values

2

TABLE I. Summary of Resistor Equations for Two-Wire and Three-Wire Pt1000 RTD Connections.

®

XTR112, XTR114

10

XTR112 1% RESISTOR VALUES FOR A THREE-WIRE RTD CONNECTION

MEASUREMENT TEMPERATURE SPAN ∆T (°C)

T

–200°C 187/267 187/536 187/806 187/1050 187/1330 187/1580 187/1820 187/2100 187/2370 187/2670

–100°C 604/255 604/499 604/4750 604/1000 604/1270 604/1500 604/1780 604/2050 604/2260

0°C 1000/243 1000/487 1000/732 1000/976 1000/1210 1000/1470 1000/1740 1000/1960

100°C 1370/237 1370/475 1370/715 1370/953 1370/1180 1370/1430 1370/1690

200°C 1740/232 1740/464 1740/698 1740/931 1740/1150 1740/1400

300°C 2100/221 2100/442 2100/665 2100/887 2100/1130

400°C 2490/215 2490/432 2490/649 2490/866

500°C 2800/210 2800/412 2800/619

600°C 3160/200 3160/402

700°C 3480/191

800°C 3740/187

100°C 200°C 300°C 400°C 500°C 600°C 700°C 800°C 900°C 1000°C

MIN

48700 31600 25500 21500 17800 15000 13000 11300 9760 8660
61900 48700 46400 44200 41200 39200 36500 34800 33200 31600

86600 49900 33200 24900 19600 15800 13300 11500 10000

110000 75000 59000 49900 44200 40200 37400 34800 32400

105000 51100 33200 24300 19100 15400 13000 11000
130000 76800 57600 48700 42200 38300 35700 33200

102000 49900 32400 23700 18700 15000 12400
127000 73200 56200 46400 40200 36500 33200

100000 48700 31600 23200 17800 14300
121000 69800 53600 44200 38300 34800

95300 46400 30100 22100 17400

118000 68100 51100 42200 36500

93100 45300 29400 21500

113000 64900 48700 40200

887000 43200 28000
107000 61900 45300

86600 42200

102000 59000

82500

100000

80600
95300

where R1 = RTD resistance at the midpoint measured temperature, (T

NOTE: The values listed in the table are 1% resistors (in Ω).
Exact values may be calculated from the following equations:

R

= RTD resistance at minimum measured temperature, T

Z

.(–)(–)

RRRR

•0 625

ZZ

R

=

G

=

R

LIN

1

R

2

LIN

R2 = RTD resistance at T

= 1kΩ (Internal)

R

LIN

21

(–)

RR

21

16

•.(–)

RRR

LIN

2

(––)

16

=

21

RRR

12

•+.( )(–)

Z

RRRR

LIN

G

2

(––)

RRR

12

MAX

21

Z

RZ/R

R

LIN1

R

LIN2

G

.

MIN

+ T

)/2

MIN

MAX

TABLE II. XTR112 RZ, RG, R

XTR114 1% RESISTOR VALUES FOR A THREE-WIRE RTD CONNECTION

T

–200°C 187/107 187/215 187/316 187/422 187/523 187/634 187/732 187/845 187/953 187/1050

–100°C 604/102 604/200 604/301 604/402 604/511 604/604 604/715 604/806 604/909

0°C 1000/97.6 1000/196 1000/294 1000/392 1000/487 1000/590 1000/681 1000/787

100°C 1370/95.3 1370/191 1370/287 1370/383 1370/475 1370/576 1370/665

200°C 1740/90.9 1740/182 1740/274 1740/365 1740/464 1740/549

300°C 2100/88.9 2100/178 2100/267 2100/357 2100/348

400°C 2490/86.6 2490/174 2490/261 2490/249

500°C 2800/82.5 2800/165 2800/49

600°C 3160/80.6 3160/162

700°C 3480/76.8

800°C 3740/75

100°C 200°C 300°C 400°C 500°C 600°C 700°C 800°C 900°C 1000°C

MIN

121000 78700 64900 53600 45300 38300 32400 28000 24900 21500
133000 95300 84500 76800 68100 68100 56200 52300 47500 45300

221000 124000 84500 61900 48700 40200 33200 28700 24900
243000 150000 110000 86600 73200 63400 57600 52300 47500

261000 130000 84500 61900 47500 39200 32400 27400
287000 154000 107000 84500 71500 61900 54900 49900

255000 124000 80600 59000 46400 37400 31600
280000 147000 105000 82500 68100 59000 52300

249000 121000 78700 57600 44200 36500
267000 143000 100000 78700 64900 56200

237000 118000 75000 54900 43200
261000 137000 95300 75000 61900

232000 113000 73200 53600
249000 133000 93100 71500

221000 110000 69800
243000 127000 88700

215000 105000
215000 121000

205000
221000

200000
215000

LIN1

, and R

Standard 1% Resistor Values for Three-Wire Pt1000 RTD Connection with Linearization.

LIN2

MEASUREMENT TEMPERATURE SPAN ∆T (°C)

RZ/R

G

R

LIN1

R

LIN2

NOTE: The values listed in the table are 1% resistors (in Ω).
Exact values may be calculated from the following equations:

= RTD resistance at minimum measured temperature, T

R

Z

RRRR

•025

.(–)(–)

R

=

G

4

• (–)

=

R

LIN

1

2

(––)
4

=

R

LIN

2

ZZ

21

RR

(–)

21

RRR

LIN

21

RRR

12

•+()(–)

Z

RRRR

LIN

2

(––)

RRR

12

G

21
Z

where R1 = RTD resistance at the midpoint measured temperature, (T

R2 = RTD resistance at T
R

= 1kΩ (Internal)

LIN

MAX

.

MIN

+ T

)/2

MIN

MAX

TABLE III. XTR114 RZ, RG, R

LIN1

, and R

Standard 1% Resistor Values for Three-Wire Pt1000 RTD Connection with Linearization.

LIN2

11

XTR112, XTR114

®

A typical two-wire RTD application with linearization is
shown in Figure 1. Resistor R
back and controls linearity correction. R

provides positive feed-

LIN1

is chosen ac-

LIN1

cording to the desired temperature range. An equation is
given in Figure 1.

In three-wire RTD connections, an additional resistor, R
is required. As with the two-wire RTD application, R
provides positive feedback for linearization. R

LIN2

LIN2

LIN1

provides
an offset canceling current to compensate for wiring resis­tance encountered in remotely located RTDs. R

LIN1

and R

LIN2

are chosen such that their currents are equal. This makes the
voltage drop in the wiring resistance to the RTD a common­mode signal which is rejected by the XTR112 and XTR114.
The nearest standard 1% resistor values for R

LIN1

and R

LIN2

should be adequate for most applications. Tables II and III
provide the 1% resistor values for a three-wire Pt1000 RTD
connection.

If no linearity correction is desired, the V

pin should be

LIN

left open. With no linearization, RG = 2500 • VFS, where
VFS = full-scale input range.

RTDs

The text and figures thus far have assumed a Pt1000 RTD.
With higher resistance RTDs, the temperature range and
input voltage variation should be evaluated to ensure proper
common-mode biasing of the inputs. As mentioned earlier,

RCM can be adjusted to provide an additional voltage drop to
bias the inputs of the XTR112 and XTR114 within their
common-mode input range.

ERROR ANALYSIS

,

Table IV shows how to calculate the effect various error
sources have on circuit accuracy. A sample error calculation
for a typical RTD measurement circuit (Pt1000 RTD, 200°C
measurement span) is provided. The results reveal the
XTR112’s and XTR114’s excellent accuracy, in this case 1%
unadjusted for the XTR112, 1.16% for the XTR114. Adjusting
resistors RG and RZ for gain and offset errors improves the
XTR112’s accuracy to 0.28% (0.31% for the XTR114). Note
that these are worst-case errors; guaranteed maximum values
were used in the calculations and all errors were assumed to be
positive (additive). The XTR112 and XTR114 achieve perfor­mance which is difficult to obtain with discrete circuitry and
requires less space.

OPEN-CIRCUIT PROTECTION

The optional transistor Q2 in Figure 3 provides predictable
behavior with open-circuit RTD connections. It assures that if
any one of the three RTD connections is broken, the XTR’s
output current will go to either its high current limit (≈ 27mA)
or low current limit (≈ 1.3mA for XTR112 and ≈ 1mA for
XTR114). This is easily detected as an out-of-range condition.

EQUAL line resistances here
creates a small common-mode
voltage which is rejected by
XTR112 and XTR114.

Resistance in this line causes
a small common-mode voltage
which is rejected by XTR112
and XTR114.

(1)

R

LIN1

2

(R

)(R

LINE2

RTD

(R

)

LINE3

3

12

1

V

13

(1)

R

LIN2

(1)

R

Z

1

)

LINE1

(2)

Q

2

2N2222

+

V

IN

4

R

G

(1)

R

G

3

R

G

2

–

V

IN

I

RET

R

CM

14

LIN

I

R1

11

I

R2

10

V

REG

V+

XTR112
XTR114

6

0.01µF

NOTES: (1) See Table I for resistor equations and
1% values. (2) Q
output current if any one RTD connection is
broken:

9

B

Q

1

E

8

I

O

7

optional. Provides predictable

2

OPEN RTD

TERMINAL

1 ≈ 1.3mA ≈ 1mA
2 ≈ 27mA ≈ 27mA
3 ≈ 1.3mA ≈ 1mA

XTR112 XTR114

I

O

0.01µF

I

O

I

O

I

O

FIGURE 3. Three-Wire Connection for Remotely Located RTDs.

®

XTR112, XTR114

12

SAMPLE ERROR CALCULATION FOR XTR112

(1)

RTD value at 4mA Output (R
RTD Measurement Range 200°C
Ambient Temperature Range (∆T
Supply Voltage Change (∆V+) 5V

) 1000Ω

RTD MIN

)20°C

A

Common-Mode Voltage Change (∆CM) 0.1V

ERROR SOURCE ERROR EQUATION ERROR CALCULATION

SAMPLE

INPUT

Input Offset Voltage V

vs Common-Mode CMRR • ∆CM/(V
Input Bias Current I
Input Offset Current I

/(V

OS

B/IREF

• R

OS

RTD MIN

EXCITATION

Current Reference Accuracy I

vs Supply (I
Current Reference Matching I

vs Supply (I

Accuracy (%)/100% • 10

REF

vs V+) • ∆V+ 25ppm/V • 5V 125 125

REF

Matching (%)/100% • I

REF

R

/(V

RTD MIN

matching vs V+) • ∆V+ • 10ppm/V • 5V • 250µA • 1000Ω/(250µA • 3.8Ω/°C • 200°C) 66 66

REF

R

RTD MIN

GAIN

Span Span Error (%)/100% • 10
Nonlinearity Nonlinearity (%)/100% • 10

OUTPUT

Zero Output (I

vs Supply (I

DRIFT (∆T

= 20°C)

A

Input Offset Voltage Drift • ∆T
Input Bias Current (typical) Drift • ∆T
Input Offset Current (typical) Drift • ∆T
Current Reference Accuracy Drift • ∆T
Current Reference Matching Drift • ∆T
Span Drift • ∆T
Zero Output Drift • ∆T

- 4mA) /16000µA • 10

ZERO

vs V+) • ∆V+/16000µA • 10

ZERO

A

• R

A

RTD MIN

• I

A

REF

A

NOISE (0.1Hz to 10Hz, typ)

Input Offset Voltage v
Current Reference I
Zero Output I

NOTES: (1) For XTR114, I
otherwise stated.

= 100µA. Total unadjusted error is 1.16%, adjusted error 0.31%. (2) All errors are min/max and referred to input, unless

REF

n

Noise • R

REF

Noise/16000µA • 10

ZERO

/(V

IN MAX

RTD MIN

6

) • 10

IN MAX

) • 10

IN MAX

6

• 10

/(V

) • 10

IN MAX

) • 10

IN MAX

/(V

)

IN MAX

/(V

) • 10

IN MAX

6

• 10

A/IREF

/(V

IN MAX

A

• R

/(V

RTD MIN

A

/16000µA • 10

6

) • 10

/(V

IN MAX

6

6

6

• 0.1%/100% • 250µA • 1000Ω/(250µA • 3.8Ω/°C • 200°C) • 10

REF

6

6

6

6

6

6

6

) • 10

100µV/(250µA • 3.8Ω/°C • 200°C) • 10

50µV/V • 0.1V/(250µA • 3.8Ω/°C • 200°C) • 10

0.025µA/250µA • 10

3nA • 1000Ω/(250µA • 3.8Ω/°C • 200°C) • 10

0.2%/100% • 10

0.2%/100% • 10

0.01%/100% • 10

25µA/16000µA • 10

0.2µA/V • 5V/16000µA • 10

1.5µV/°C • 20°C/(250µA • 3.8Ω/°C • 200°C) • 10
20pA/°C • 20°C/250µA • 10

5pA/°C • 20°C • 1000Ω/(250µA • 3.8Ω/°C • 200°C) • 10

35ppm/°C • 20°C 700 700

) 15ppm/°C • 20°C • 250µA • 1000Ω/(250µA • 3.8Ω/°C • 200°C) 395 395

IN MAX

6

) • 10

6

6

3nA • 1000Ω/(250µA • 3.8Ω/°C • 200°C) • 10

25ppm/°C • 20°C 500 500

0.5µA/°C • 20°C/16000µA • 10

0.6µV/(250µA • 3.8Ω/°C • 200°C) • 10

0.03µA/16000µA • 10

(2)

6

6

Total Excitation Error: 3507 191

6

6

6

6

6

6

ERROR

(ppm of Full Scale)

UNADJ. ADJUST.

6

6

6

526 0

26 26

100 0

16 0

Total Input Error: 668 26

2000 0

6

1316 0

2000 0

100 100

Total Gain Error: 2100 100

1563 0

63 63

Total Output Error: 1626 63

6

6

6

158 158

22

0.5 0.5

626 626

Total Drift Error: 2382 2382

6

6

33

16 16

22

Total Noise Error: 21 21

TOTAL ERROR: 10304 2783

(1.03%) (0.28%)

TABLE IV. Error Calculation.

REVERSE-VOLTAGE PROTECTION

The XTR112’s and XTR114’s low compliance rating (7.5V)
permits the use of various voltage protection methods with­out compromising operating range. Figure 4 shows a diode
bridge circuit which allows normal operation even when the
voltage connection lines are reversed. The bridge causes a
two diode drop (approximately 1.4V) loss in loop supply
voltage. This results in a compliance voltage of approxi­mately 9V—satisfactory for most applications. If 1.4V drop
in loop supply is too much, a diode can be inserted in series
with the loop supply voltage and the V+ pin. This protects
against reverse output connection lines with only a 0.7V loss
in loop supply voltage.

SURGE PROTECTION

Remote connections to current transmitters can sometimes be
subjected to voltage surges. It is prudent to limit the maximum
surge voltage applied to the XTR to as low as practical.
Various zener diode and surge clamping diodes are specially
designed for this purpose. Select a clamp diode with as low a
voltage rating as possible for best protection. For example, a
36V protection diode will assure proper transmitter operation
at normal loop voltages, yet will provide an appropriate level
of protection against voltage surges. Characterization tests on
three production lots showed no damage to the XTR112 or
XTR114 within loop supply voltages up to 65V.

13

XTR112, XTR114

®

Most surge protection zener diodes have a diode character­istic in the forward direction that will conduct excessive
current, possibly damaging receiving-side circuitry if the
loop connections are reversed. If a surge protection diode is
used, a series diode or diode bridge should be used for
protection against reversed connections.

RADIO FREQUENCY INTERFERENCE

The long wire lengths of current loops invite radio frequency
interference. RF can be rectified by the sensitive input
circuitry of the XTR112 and XTR114 causing errors. This
generally appears as an unstable output current that varies
with the position of loop supply or input wiring.

If the RTD sensor is remotely located, the interference may
enter at the input terminals. For integrated transmitter as­semblies with short connection to the sensor, the interfer­ence more likely comes from the current loop connections.

Bypass capacitors on the input reduce or eliminate this input
interference. Connect these bypass capacitors to the I

RET

terminal as shown in Figure 5. Although the dc voltage at the
I

terminal is not equal to 0V (at the loop supply, VPS) this

RET

circuit point can be considered the transmitter’s “ground.”
The 0.01µF capacitor connected between V+ and IO may
help minimize output interference.

10

V+

XTR112
XTR114

I

RET

B

9

E

8

I

O

7

6

0.01µF

(1)

D

1

1N4148

Diodes

The diode bridge causes
a 1.4V loss in loop supply
voltage.

FIGURE 4. Reverse Voltage Operation and Over-Voltage Surge Protection.

12

1

V

LIN

13

R

G

I

R1

+

V

4

R

3

R

V

2

I

R2

IN

G

XTR112
XTR114

G

–
IN

I

RET

6

R

LIN1RLIN2

1kΩ

1kΩ

R

Z

0.01µF 0.01µF

NOTE: (1) Zener Diode 36V: 1N4753A or General
Semiconductor Transorb

TM

1N6286A. Use lower
voltage zener diodes with loop power supply
voltages less than 30V for increased protection.
See “Over-Voltage Surge Protection.”

Maximum V
less than minimum

R

L

14

11

10

V

REG

V+

9

B

E

8

I

O

7

voltage rating of zener

V

PS

diode.

0.01µF

must be

PS

RTD

(1)

R

CM

0.01µF

NOTE: (1) Bypass capacitors can be connected
to either the I

FIGURE 5. Input Bypassing Technique with Linearization.

®

XTR112, XTR114

pin or the IO pin.

RET

14

I

< 2mA

Isothermal

REG

5V

Block

12

1

V

LIN

+

V

IN

4

R

G

3

R

G

–

V

2

IN

I

RET

I

R1

6

I

R2

XTR112
XTR114

14

11

10

V

REG

V+

9

B

E

8

I

O

7

+–

IO = 4mA + (VIN –VIN)

40
R

G

NOTES: (1) For burn-out indication.

(2) XTR112, R

XTR114, R

= 3.3kΩ

CM

= 8.2kΩ

CM

Type J

1N4148

50Ω

1kΩ

25Ω

1MΩ

V+

OPA277

13

V–

(1)

1MΩ

0.01µF

R

G

1250Ω

20kΩ

(2)

R

CM

FIGURE 6. Thermocouple Low Offset, Low Drift Loop Measurement with Diode Cold-Junction Compensation.

12

1

V

LIN

14

I

R1

+

V

IN

R

G

11

I

R2

V

REG

XTR112

R

G

–

V

IN

I

RET

6

Pt1000

100°C to

600°C

RTD

R

LIN1

18.7kΩ

R

1370Ω

R

CM

Z

R

G

1270Ω

13

4

3

2

0.01µF

FIGURE 7. ±12V Powered Transmitter/Receiver Loop.

1N4148

10

+12V

V+

9EB

8

I

O

7

IO = 4mA – 20mA

0.01µFQ

1

16

10

3

RCV420

2

4

–12V

NOTE: A two-wire RTD connection is shown. For remotely
located RTDs, a three-wire RTD conection is recommended. R
becomes 1180Ω, R

is 40.2kΩ. See Figure 3 and Table II.

LIN2

11

5

1µF

1µF

G

12

= 0 to 5V

V

15

O

14

13

15

®

XTR112, XTR114

RTD

12

R

LIN1

R

LIN2

13

4

R

G

3

R

Z

2

1

V

LIN

14

I

R1

I

R2

XTR112
XTR114

11

V

REG

10

V+

9

B
E

8

I

O

7

IO = 4mA – 20mA

+

V

IN

R

G

R

G

–

V

IN

I

RET

6

1N4148

+15V

1µF

1µF

0.01µFQ

1

3

2

16

10

11

RCV420

5

4

12

15

14

13

15

ISO124

16

0

–15V

1

10

2

Isolated Power
from PWS740

V+

9

7

V

8

0 – 5V

V–

O

NOTE: A three-wire RTD connection is shown.

R

CM

0.01µF

For a two-wire RTD connection, eliminate R

FIGURE 8. Isolated Transmitter/Receiver Loop.

200µA (XTR114)
500µA (XTR112)

13

R

G

.

LIN2

12

1

V

LIN

+

V

IN

4

R

G

3

R

G

I

R1

14

I

R2

V

XTR112
XTR114

REG

11

10

V+

9

B

8

E

(1)

R

CM

FIGURE 9. Bridge Input, Current Excitation.

®

XTR112, XTR114

–

2

V

IN

I

RET

7

6

NOTE: (1) Use RCM to adjust the
common-mode voltage to within

1.25V to 3.5V.

16

PACKAGE OPTION ADDENDUM

www.ti.com

22-Oct-2007

PACKAGING INFORMATION

Orderable Device Status

(1)

Package

Type

Package
Drawing

Pins Package

Qty

Eco Plan

XTR112U ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

XTR112UA ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

XTR112UAE4 ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

XTR112UE4 ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

XTR114U ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

XTR114UA ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

XTR114UAE4 ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

XTR114UE4 ACTIVE SOIC D 14 58 Green (RoHS &

no Sb/Br)

(1)

The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in

a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.

(2)

Lead/Ball Finish MSL Peak Temp

CU NIPDAU Level-3-260C-168 HR

CU NIPDAU Level-3-260C-168 HR

CU NIPDAU Level-3-260C-168 HR

CU NIPDAU Level-3-260C-168HR

CU NIPDAU Level-3-260C-168HR

CU NIPDAU Level-3-260C-168HR

CU NIPDAU Level-3-260C-168HR

CU NIPDAU Level-3-260C-168HR

(3)

(2)

Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check

http://www.ti.com/productcontent for the latest availability information and additional product content details.

TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements

for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)

(3)

MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder

temperature.

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Addendum-Page 1

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