FEATURES

COMPLETE TRANSMITTER + RTD

LINEARIZATION

TWO-WIRE, 4-20mA OUTPUT

VOLTAGE OUTPUT (0.5V to 4.5V)

ELIMINATES POTENTIOMETERS AND

TRIMMING

DIGITALLY CALIBRATED

5V SUB-REGULATOR OUTPUT

SERIAL SPI BUS INTERFACE

SSOP-24 PACKAGE

APPLICATIONS

REMOTE RTD TRANSMITTERS

PRESSURE BRIDGE TRANSMITTERS

STRAIN GAGE TRANSMITTERS

SCADA REMOTE DATA ACQUISITION

WEIGHING SYSTEMS

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 burnout

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.