TEXAS INSTRUMENTS XTR115, XTR116 Technical data

XTR115

XTR115

XTR116

XTR116

SBOS124A – JANUARY 2000 – REVISED NOVEMBER 2003

4-20mA CURRENT LOOP TRANSMITTERS

FEATURES

● LOW QUIESCENT CURRENT: 200µA

● 5V REGULATOR FOR EXTERNAL CIRCUITS

● V

FOR SENSOR EXCITATION:

REF

XTR115: 2.5V
XTR116: 4.096V

● LOW SPAN ERROR: 0.05%

● LOW NONLINEARITY ERROR: 0.003%

● WIDE LOOP SUPPLY RANGE: 7.5V to 36V

● SO-8 PACKAGE

DESCRIPTION

The XTR115 and XTR116 are precision current out­put converters designed to transmit analog 4-to-20mA
signals over an industry standard current loop. They
provide accurate current scaling and output current
limit functions.

The on-chip voltage regulator (5V) can be used to
power external circuitry. A precision on-chip V
(2.5V for XTR115 and 4.096V for XTR116) can be

REF

APPLICATIONS

● 2-WIRE, 4-20mA CURRENT LOOP

TRANSMITTER

● SMART TRANSMITTER

● INDUSTRIAL PROCESS CONTROL

● TEST SYSTEMS

● COMPATIBLE WITH HART MODEM

● CURRENT AMPLIFIER

● VOLTAGE-TO-CURRENT AMPLIFIER

used for offsetting or to excite transducers. A current
return pin (I
circuitry to assure an accurate control of the output
current.

The XTR115 is a fundamental building block of
smart sensors using 4-to-20mA current transmission.

The XTR115 and XTR116 are specified for opera­tion over the extended industrial temperature range,
–40°C to +85°C.

) senses any current used in external

RET

XTR115
XTR116

V

+5V

XTR115: 2.5V

XTR116: 4.096V

+

V

IN

–

REG

8

V

REF

1

R

IN

I

IN

2

3

I

RET

R

1

2.475kΩ

Voltage

Reference

A1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.

+5V

Regulator

R

LIM

R

2

25Ω

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V+
7

V
B
6

E
5

100 V

IN

I

=

O

R

IN

4

I = 100 • I

IN

Copyright © 2000-2003, Texas Instruments Incorporated

LOOP

R

L

SPECIFICATIONS

At TA = +25°C, V+ = 24V, R

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
OUTPUT

Output Current Equation I
Output Current, Linear Range 0.25 25 ✻✻mA
Over-Scale Limit I
Under-Scale Limit I

SPAN

Span (Current Gain) S 100 ✻ A/A

(1)

Error

vs Temperature T

Nonlinearity I

INPUT

Offset Voltage (Op Amp) V

vs Temperature T
vs Supply Voltage, V+ V+ = 7.5V to 36V ±0.1 ±2 ✻✻ µV/V

Bias Current I

vs Temperature 150 ✻ pA/°C

Noise: 0.1Hz to 10Hz e

DYNAMIC RESPONSE

Small Signal Bandwidth C
Slew Rate 3.2 ✻ mA/µs

(2)

V

REF

XTR115 2.5 ✻ V
XTR116 4.096 ✻ V

Voltage Accuracy I

vs Temperature T
vs Supply Voltage, V+ V+ = 7.5V to 36V ±1 ±10 ✻✻ ppm/V

vs Load I
Noise: 0.1Hz to 10Hz 10 ✻ µVp-p
Short-Circuit Current 16 ✻ mA

(2)

V

REG

Voltage 5 ✻ V
Voltage Accuracy I

vs Temperature T

vs Supply Voltage, V+ V+ = 7.5V to 36V 1 ✻ mV/V

vs Output Current See Typical Curves
Short-Circuit Current 12 ✻ mA

POWER SUPPLY V+
Specified +24 ✻ V
Voltage Range +7.5 +36 ✻✻V
Quiescent Current 200 250 ✻✻ µA

Over Temperature, –40°C to +85°C 240 300 ✻✻ µA

TEMPERATURE RANGE

Specification –40 +85 ✻✻°C
Operating –55 +125 ✻✻°C
Storage –55 +125 ✻✻°C
Thermal Resistance

✻ Specifications the same as XTR115U and XTR116U.
NOTES: (1) Does not include initial error or TCR of R

= 20kΩ, and TIP29C external transistor, unless otherwise noted.

IN

IO = IIN • 100 ✻

MIN

LIM

O

I

= 0, I

REG

= 0 0.2 0.25 ✻✻ mA

REF

IIN = 250µA to 25mA ±0.05 ±0.2 ✻ ±0.4 %

= –40°C to +85°C ±3 ±20 ✻✻ ppm/°C

A

= 250µA to 25mA ±0.003 ±0.01 ✻ ±0.02 %

IN

OS

B

n

θ

JA

IIN = 40µA ±100 ±250 ✻ ±500 µV

= –40°C to +85°C ±0.7 ±3 ✻ ±6 µV/°C

A

= 0, RL = 0 380 ✻ kHz

LOOP

= 0 ±0.05 ±0.25 ✻ ±0.5 %

REF

= –40°C to +85°C ±20 ±35 ✻ ±75 ppm/°C

A

= 0mA to 2.5mA ±100 ✻ ppm/mA

REF

= 0 ±0.05 ±0.1 ✻✻ V

REG

= –40°C to +85°C ±0.1 ✻ mV/°C

A

. (2) Voltage measured with respect to I

IN

XTR115U XTR115UA
XTR116U XTR116UA

32 ✻ mA

–35 ✻ nA

0.6 ✻ µVp-p

150 ✻ °C/W

pin.

RET

2

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XTR115, XTR116

SBOS124A

PIN CONFIGURATION

Top View SO-8

1

V

REF

2

IIN

3

I

RET

4

I

O

8

V

7

V+

6

B (Base)

5

E (Emitter)

REG

ABSOLUTE MAXIMUM RATINGS

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

Input Voltage (referenced to I

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

V

, Short-Circuit.................................................................. Continuous

REG

V

, Short-Circuit .................................................................. Continuous

REF

Operating Temperature ................................................ –55°C to +125°C

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

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

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.

pin)........................................0V to V+

RET

(1)

ELECTROSTATIC

PACKAGE/ORDERING INFORMATION

For the most current package and ordering information, see
the Package Option Addendum located at the end of this
data sheet.

DISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Texas Instru­ments 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.

XTR115, XTR116

SBOS124A

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3

TYPICAL PERFORMANCE CURVES

At TA = +25°C, V+ = 24V, R

= 20kΩ, and TIP29C external transistor, unless otherwise noted.

IN

CURRENT GAIN vs FREQUENCY

40

30

Gain (dB)

20

10

10k 100k

0.1

0

–0.1

–0.2

∆ Reference Voltage (%)

REFERENCE VOLTAGE vs TEMPERATURE

C

R

Frequency (Hz)

= 10nF

OUT

= 250Ω

L

C

R

OUT

= 0Ω

L

= 0

1M

260

240

220

200

Quiescent Current (µA)

180

160

QUIESCENT CURRENT vs TEMPERATURE

(V+) = 36V

(V+) = 7.5V

–75 –50 –25 0 25 50 75 100

Temperature (°C)

OVER-SCALE CURRENT vs TEMPERATURE

34

With External Transistor

33

32

V+ = 36V

31

30

Over-Scale Current (mA)

29

V+ = 24V

V+ = 7.5V

(V+) = 24V

125

–0.3

–75 –50 –25 0 25 50 75 100

Temperature (°C)

V

5.5
+125°C

VOLTAGE vs V

REG

CURRENT

REG

–55°C

5.0

+25°C

Voltage (V)

REG

V

Sinking
Current

Sourcing

Current

+25°C

4.5

–10123

Current (mA)

I

REG

–55°C

+125°C

125

28

–75 –50 –250 255075100

125

Temperature (°C)

4

4

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XTR115, XTR116

SBOS124A

APPLICATIONS INFORMATION

The XTR115 and XTR116 are identical devices except for
the reference voltage output, pin 1. This voltage is available
for external circuitry and is not used internally. Further
discussions that apply to both devices will refer to the
“XTR115/6.”

Figure 1 shows basic circuit connections with representative
simplified input circuitry. The XTR115/6 is a two-wire
current transmitter. Its input signal (pin 2) controls the output
current. A portion of this current flows into the V+ power
supply, pin 7. The remaining current flows in Q1. External
input circuitry connected to the XTR115/6 can be powered
from V
must be returned to I
ground” for input circuitry driving the XTR115/6.

The XTR115/6 is a current-input device with a gain of 100.
A current flowing into pin 2 produces IO = 100 • IIN. The
input voltage at the IIN pin is zero (referred to the I
A voltage input is created with an external input resistor, as
shown. Common full-scale input voltages range from 1V

REG

or V

. Current drawn from these terminals

REF

, pin 3. This I

RET

pin is a “local

RET

RET

pin).

and upward. Full-scale inputs greater than 0.5V are recom­mend to minimize the effect of offset voltage and drift of A1.

EXTERNAL TRANSISTOR

The external transistor, Q1, conducts the majority of the full­scale output current. Power dissipation in this transistor can
approach 0.8W with high loop voltage (40V) and 20mA
output current. The XTR115/6 is designed to use an external
transistor to avoid on-chip thermal-induced errors. Heat
produced by Q1 will still cause ambient temperature changes
that can affect the XTR115/6. To minimize these effects,
locate Q1 away from sensitive analog circuitry, including
XTR115/6. Mount Q1 so that heat is conducted to the
outside of the transducer housing.

The XTR115/6 is designed to use virtually any NPN transis­tor with sufficient voltage, current and power rating. Case
style and thermal mounting considerations often influence
the choice for any given application. Several possible choices
are listed in Figure 1. A MOSFET transistor will not improve
the accuracy of the XTR115/6 and is not recommended.

XTR115: 2.5V

XTR116: 4.096V

For IO = 4mA to 20mA

I

IN

With R

V

Input

Circuitry

= 40µA to 200µA

= 20kΩ

IN

= 0.8V to 4V

IN

I

REG

I

REF

R

20kΩ

V

IN

All return current

from I

REG

NOTE: (1) See also Figure 5.

IN

and I

XTR115
XTR116

V

5V

REF

REG

8

(1)

V

REF

1

I

IN

I

IN

2

3

I

RET

R

1

2.475kΩ

Voltage

Reference

A1

+5V

Regulator

R

25Ω

V+
7

B

Q

1

6

E

R

LIM

2

5

I

O

4

I

O

10nF

I = 100 • I

IN

Possible choices for Q1 (see text).

TYPE

2N4922
TIP29C
TIP31B

PACKAGE

TO-225
TO-220
TO-220

V

LOOP

R

L

FIGURE 1. Basic Circuit Connections.

XTR115, XTR116

SBOS124A

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5