XTR108

SBOS187C – OCTOBER 2001 – REVISED JULY 2005

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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.

Copyright © 2001-2005, Texas Instruments Incorporated

SPI is a trademark of Motorola, Inc. All other trademarks are the property of their respective owners.

4-20mA, TWO-WIRE TRANSMITTER

“Smart” Programmable with Signal Conditioning

FEATURES

q COMPLETE TRANSMITTER + RTD

LINEARIZATION

q TWO-WIRE, 4-20mA OUTPUT

q VOLTAGE OUTPUT (0.5V to 4.5V)

q ELIMINATES POTENTIOMETERS AND

TRIMMING

q DIGITALLY CALIBRATED

q 5V SUB-REGULATOR OUTPUT

q SSOP-24 PACKAGE

APPLICATIONS

q REMOTE RTD TRANSMITTERS

q PRESSURE BRIDGE TRANSMITTERS

q STRAIN GAGE TRANSMITTERS

q SCADA REMOTE DATA ACQUISITION

q WEIGHING SYSTEMS

q INDUSTRIAL PROCESS CONTROL

DESCRIPTION

The XTR108 is a “smart,” programmable, 4-20mA, two-wire

transmitter designed for temperature and bridge sensors.

Zero, span, and linearization errors in the analog signal

path can be calibrated via a standard digital serial interface,

eliminating manual trimming. Non-volatile external EEPROM

stores calibration settings.

The all-analog signal path contains an input multiplexer,

autozeroed programmable-gain instrumentation amplifier, dual

programmable current sources, linearization circuit, voltage

reference, sub-regulator, internal oscillator, control logic, and

an output current amplifier. Programmable level shifting

compensates

for

sensor

DC

offsets.

Selectable

up- and down-scale output indicates out-of-range and burn-

out per NAMUR NE43. Automatic reset is initiated when

supply is lost.

Current sources, steered through the multiplexer, can be

used to directly excite RTD temperature sensors, pressure

bridges, or other transducers. An uncommitted op amp can

be used to convert current into a voltage. The XTR108 is

specified for –40

°C to +85°C.

XTR1

08

SPI and

Control Circuits

4-20mA

EEPROM

Linearization

Excitation

I

Ret

V/I-0

V/I-1

V/I-2

V/I-3

V/I-4

V/I-5

RTD

PGA

V/I

V

PS

XTR108

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.