Document
®
XTR XTR 114
112
XTR112 XTR114
4-20mA CURRENT TRANSMITTERS with Sensor Excitation and Linearization
FEATURES
q LOW UNADJUSTED ERROR q PRECISION CURRENT SOURCES XTR112: Two 250µA XTR114: Two 100µA q RTD OR BRIDGE EXCITATION q LINEARIZATION q TWO OR THREE-WIRE RTD OPERATION q LOW OFFSET DRIFT: 0.4µV/°C q LOW OUTPUT CURRENT NOISE: 30nAp-p q HIGH PSR: 110dB min q HIGH CMR: 86dB min q WIDE SUPPLY RANGE: 7.5V TO 36V q SO-14 SOIC PACKAGE
APPLICATIONS
q q q q INDUSTRIAL PROCESS CONTROL FACTORY AUTOMATION SCADA REMOTE DATA ACQUISITION REMOTE TEMPERATURE AND PRESSURE TRANSDUCERS
Pt1000 NONLINEARITY CORRECTION USING XTR112 and XTR114 5 4 Nonlinearity (%) 3 2 1 0 –1 –200°C Process Temperature (°C) +850°C
Uncorrected RTD Nonlinearity
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 integrated 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. Instrumentation amplifier gain can be configured for a 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 package and are specified for the –40°C to +85°C industrial temperature range.
Corrected Nonlinearity
IR IR VLIN VREG + 7.5V to 36V VPS 4-20 mA RG RTD – XTR112: IR = 250µA XTR114: IR = 100µA XTR112 XTR114 VO 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 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
®
©
1998 Burr-Brown Corporation
PDS-1473A 1
Printed in U.S.A. December, 1998 XTR112, XTR114
SPECIFICATIONS
At TA = +25°C, V+ = 24V, and TIP29C external transistor, unless otherwise noted. XTR112U XTR114U PARAMETER OUTPUT Output Current Equation Output Current, Specified Range Over-Scale Limit Under-Scale Limit: XTR112 XTR114 ZERO OUTPUT(1) Initial Error vs Temperature vs Supply Voltage, V+ vs Common-Mode Voltage vs VREG Output Current Noise: 0.1Hz to 10Hz SPAN Span Equation (transconductance) Initial Error (3) vs Temperature(3) Nonlinearity: Ideal Input (4) INPUT(5) Offset Voltage vs Temperature vs Supply Voltage, V+ vs Common-Mode Voltage, RTI (CMRR) Common-Mode Input Range(2) Input Bias Current vs Temperature Input Offset Current vs Temperature Impedance: Differential Common-Mode Noise: 0.1Hz to 10Hz CURRENT SOURCES Current: XTR112 XTR114 Accuracy vs Temperature vs Power Supply, V+ Matching vs Temperature vs Power Supply, V+ Compliance Voltage, Positive Negative(2) Output Impedance: XTR112 XTR114 Noise: 0.1Hz to 10Hz: XTR112 XTR114 VREG(2) Accuracy vs Temperature vs Supply Voltage, V+ Output Current: XTR112 XTR114 Output Impedance LINEARIZATION RLIN (internal) Accuracy vs Temperature POWER SUPPLY Specified Voltage Operating Voltage Range TEMPERATURE RANGE Specification, TMIN to TMAX Operating /Storage Range Thermal Resistance, θJA SO-14 Surface-Mount T 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 IRET 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 include Zero Output initial error. (6) Current source output voltage with respect to IRET pin.
®
XTR112UA XTR114UA MAX MIN TYP MAX UNITS A mA mA mA mA mA µA µA/°C µA/V µA/V µA/mA µAp-p A/V % ppm/°C % µV µV/°C µV/V µV/V V nA pA/°C nA pA/°C GΩ || pF GΩ || pF µVp-p µA µA % ppm/°C ppm/V % ppm/°C ppm/V V V MΩ GΩ µAp-p µAp-p V V mV/°C mV/V mA mA Ω kΩ % ppm/°C V V °C °C °C/W
CONDITIONS
MIN
TYP
IREG = 0 VIN = 0V, RG = ∞
4 24 0.9 0.6
IO = VIN • (40/RG) + 4mA, VIN in Volts, RG in Ω 20 T 27 30 T T 1.3 1.7 T T 1 1.4 T T 4 ±5 ±0.07 0.04 0.02 0.3 0.03 S = 40/RG ±0.05 ±3 0.003 ±50 ±0.4 ±0.3 ±10 ±25 ±0.5 0.2 T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T +36 +85 +125 100 T T T T
T T T T ±50 ±0.9 T
V+ = 7.5V to 36V VCM = 1.25V to 3.5V(2)
Full Scale (VIN) = 50mV Full Scale (VIN) = 50mV VCM = 2V V+ = 7.5V to 36V VCM = 1.25V to 3.5V(2) 1.25
±0.2 ±25 0.01 ±100 ±1.5 ±3 ±50 3.5 25 ±3
±0.4 T T ±250 ±3 T ±100 T 50 ±10
5 20 ±0.2 5 0.1 || 1 5 || 10 0.6 VO = 2V(6) 250 100 ±0.05 ±15 ±10 ±.