4-20mA Current-Loop Transmitter

www.DataSheet4U.com XTR117 SBOS344 − SEPTEMBER 2005 4-20mA Current-Loop Transmitter FEATURES D D D D D D LOW QUIESCENT CURRENT: 130µA 5V REGULATOR FOR EXTERNAL CIRCUITS LOW SPAN ERROR: 0.05% LOW NONLINEARITY ERROR: 0.003% WIDE-LOOP SUPPLY RANGE: 7.5V to 40V MSOP-8 PACKAGE DESCRIPTION The XTR117 is a precision current output converter designed to transmit analog 4-20mA signals over an industry- standard current loop. It provides accurate current scaling and output current limit functions. The on-chip voltage regulator (5V) can be used to power external circuitry. A current return pin (IRET) senses any current used in external circuitry to assure an accurate control of the output current. The XTR117 is a fundamental building block of smart sensors using 4-20mA current transmission. The XTR117 is specified for operation over the extended industrial temperature range, −40°C to +125°C. APPLICATIONS D 2-WIRE, 4-20mA CURRENT LOOP D D D D D TRANSMITTER SMART TRANSMITTER INDUSTRIAL PROCESS CONTROL TEST SYSTEMS CURRENT AMPLIFIER VOLTAGE-TO-CURRENT AMPLIFIER RELATED 4-20mA PRODUCTS XTR115 XTR116 5V regulator output and 2.5V reference output 5V regulator output and 4.096V reference output NOTE: For 4-20mA complete bridge and RTO conditioner solutions, see the XTR product family at www.ti.com. VREG 8 XTR117 +5V Regulator V+ 7 B 6 Q1 IO RIN I IN 2 A1 E 5 IRET 3 R1 2.475kΩ R2 25Ω RLIM IO = 100 VIN RIN 4 VLOOP VIN RL 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. Copyright  2005, Texas Instruments Incorporated www.ti.com XTR117 www.ti.com SBOS344 − SEPTEMBER 2005 ABSOLUTE MAXIMUM RATINGS(1) Power Supply, V+ (referenced to IO pin) . . . . . . . . . . . . . . . . +50V Input Voltage, (referenced to IRET pin) . . . . . . . . . . . . . . . 0V to V+ Output Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous VREG, Short-Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous Operating Temperature Range . . . . . . . . . . . . . . . −55°C to +125°C Storage Temperature Range . . . . . . . . . . . . . . . . . −55°C to +125°C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +165°C ESD Rating (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . 2000V (Charged Device Model) . . . . . . . . . . . . . . . . . 1000V (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. ELECTROSTATIC 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. PACKAGE/ORDERING INFORMATION(1) PRODUCT XTR117 XTR117(2) PACKAGE-LEAD MSOP-8 DFN-8 PACKAGE DESIGNATOR DGK DRB PACKAGE MARKING BOZ BOY ORDERING NUMBER XTR117AIDGKT XTR117AIDGKR XTR117AIDRBT TRANSPORT MEDIA, QUANTITY Tape and Reel, 250 Tape and Reel, 2500 Tape and Reel, 250 XTR117AIDRBR Tape and Reel, 3000 (1) For the most current package and ordering information, see the Package Option Addendum located at the end of this data sheet. (2) Available Q1 2006. PIN ASSIGNMENTS Top View XTR117 XTR117 NC(1) IIN IRET IO 1 2 3 4 8 7 6 5 VREG V+ B (Base) E (Emitter) NC(1) IIN IRET IO 1 2 3 4 Exposed Thermal Die Pad on Underside(2) 8 VREG 7 V+ 6 B (Base) 5 E (Emitter) MSOP−8 DFN−8(3) NOTES: (1) NC = No connection. Leave unconnected on PCB. (2) Connect thermal die pad to V−. (3) Available Q1 2006. 2 XTR117 www.ti.com SBOS344 − SEPTEMBER 2005 ELECTRICAL CHARACTERISTICS: V+ = +24V Boldface limits apply over the temperature range, TA = −40°C to +125°C. All specifications at TA = +25°C, V+ = 24V, RIN = 20kΩ, and TIP29C external transistor, unless otherwise noted. PARAMETER OUTPUT Output Current Equation Output Current, Linear Range Over-Scale Limit Under-Scale Limit SPAN Span (Current Gain) Error(1) vs Temperature Nonlinearity INPUT Offset Voltage (Op Amp) vs Temperature vs Supply Voltage, V+ Bias Current vs Temperature Noise: 0.1Hz to 10Hz DYNAMIC RESPONSE Small-Signal Bandwidth Slew Rate VREG(2) Voltage Voltage Accuracy vs Temperature vs Supply Voltage, V+ vs Output Current Short-Circuit Current POWER SUPPLY Specified Voltage Range Operating Voltage Range Quiescent Current Over Temperature TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance MSOP DFN V+ +7.5 IQ TA = −40°C to +125°C −40 −55 −55 130 IO 0.20 ILIM IMIN S IO = 200µA to 25mA TA = −40°C to +125°C IO = 200µA to 25mA VOS IIN = 40µA TA = −40°C to +125°C V+ = 7.5V to 40V TA = −40°C to +125°C en CLOOP = 0, RL = 0 IREG = 0 32 0.13 100 ±0.05 +3 ±0.003 ±100 +0.7 +0.1 −35 150 0.6 380 3.2 5 ±0.05 ±0.1 +0.1 1 See Typical Characteristics 12 +24 +40 200 250 +125 +125 +150 150 53 CONDITION MIN XTR117 TYP IO = IIN x 100 25 0.20 mA mA mA A/A % ppm/°C % µV mV/°C µV/V nA pA/°C µVPP kHz mA/µs V MAX UNITS ±0.4 +20 ±0.02 ±500 +6 +2 IB IREG = 0 TA = −40°C to +125°C V+ = 7.5V to 40V V mV/°C mV/V mA V V µA mA °C °C °C °C/W °C/W qJA (1) Does not include initial error or temperature coefficient of RIN. (2) Voltage measured with respect to IRET pin. 3 XTR117 www.ti.com SBOS344 − SEPTEMBER 2005 TYPICAL CHARACTERISTICS: V+ = +2.7V to +5.5V At TA = +25°C, V+ = 24V, RIN = 20kΩ, and TIP29C external transistor, unless otherwise noted. CURRENT GAIN vs FREQUENCY 45 40 Quiescent Current (µA) 180 170 160 150 140 130 120 110 100 90 10 10k 100k Frequency (Hz) 1M 80 −75 QUIESCENT CURRENT vs TEMPERATURE V+ = 36V Gain (dB) 30 COUT = 0 RL = 0Ω COUT = 10nF RL = 250Ω V+ = 24V 20 V+ = 7.5V −50 −25 0 25 50 75 100 125 Temperature (_C) OVER− SCALE CURRENT vs TEMPERATURE 34 With External Transistor Over− Scale Current (mA) 33 32 V+ = 36V 31 V+ = 7.5V 30 V+ = 24V 29 28 −75 −50 −25 0 25 50 75 100 125 Temperature (_ C) 4.5 −1 Sinking Current VREG Voltage (V) 5.5 +125_C VREG VOLTAGE vs VREG CURRENT −55_ C −55_ C +25_C 5.0 +25_ C Sourcing Current +125_ C 0 1 2 3 4 IREG Current (mA) SPAN ERROR vs TEMPERATURE 50 40 30 Span Error (m%) Population 20 10 0 −10 −20 −30 −40 −75 −50 −25 0 25 50 75 100 125 −50 OFFSET VOLTAGE DISTRIBUTION Temperature (_C) 4 −500 −450 −400 −350 −300 −250 −200 −150 −100 −50 0 50 100 150 200 250 300 350 400 450 500 Offset Voltage (µV) XTR117 www.ti.com SBOS344 − SEPTEMBER 2005 APPLICATIONS INFORMATION BASIC OPERATION The XTR117 is a precision current output converter designed to transmit analog 4-20mA signals over an industry-standard current loop. Figure 1 shows basic circuit connections with representative simplified input circuitry. The XTR117 is a two-wire current transmitter. Its input current (pin 2) controls the output current. A portion of the output current flows into the V+ power supply, pin 7. The remaining current flows in Q1. External input circuitry connected to the XTR117 can be powered from VREG. Current drawn from these terminals must be returned to IRET, pin 3. The IRET pin is a local ground for input circuitry driving the XTR117. The XTR117 is a current-input device with a gain of 100. A current flowing into pin 2 produces IO = 100 x IIN. The input voltage at the IIN pin is zero (referred to the IRET pin). A voltage input is converted to an input current with an external input resistor, RIN, as shown in Figure 1. Typical full-scale input voltages range from 1V and upward. Full-scale inputs greater than 0.5V are recommend to minimize the effects of offset voltage and drift of A1. EXTERNAL TRANSISTOR The external transistor, Q1, conducts the majority of the full-scale output current. Power dissipation in this transistor can approach 0.8W with high loop voltage (40V) and 20mA output current. The XTR117 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 influence the XTR117 performance. To minimize these effects, locate Q1 away from sensitive analog circuitry, including XTR117. Mount Q1 so that heat is conducted to the outside of the transducer housing. The XTR117 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 XTR117 and is not recommended. For improved precision use an external voltage reference. DEVICE REF3140 REF3130 REF3125 VOLTAGE 4.096V 3.0V 2.5V Possible choices for Q1 (see text): TYPE MJE3440 TIP41C MJD3340 PACKAGE SOT−32 TO−220 D−PAK Use REF32xx for lower drift. (VREF) IREG 5V XTR117 VREG 8 +5V Regulator V+ 7 B 6 IIN IIN 2 A1 E 5 IRET 3 from I REG and IREF All return current R1 2.475kΩ R2 25Ω R LIM COUT 10nF RL Q1 VLOOP IO Input Circuitry VIN RIN 20kΩ IO 4 I = 100 (IIN) Figure 1. Basic Circuit Co