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2-Wire XTR Products NOT FOR 3-Wire XTR Applications

2-Wire XTR Products NOT FOR 3-Wire XTR Applications. 4 to 20mA Current Loop. Needs only 2 Wires (normally loosely twisted, sometimes shielded) for all of these functions: Sensor Excitation Signal Conditioning Signal Transmission. XTR. 4 to 20mA Current Loop. Supply Voltage. XTR.

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2-Wire XTR Products NOT FOR 3-Wire XTR Applications

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  1. 2-Wire XTR ProductsNOT FOR3-Wire XTR Applications

  2. 4 to 20mA Current Loop Needs only 2 Wires (normally loosely twisted, sometimes shielded) for all of these functions: • Sensor Excitation • Signal Conditioning • Signal Transmission jm-Sept 05

  3. XTR 4 to 20mA Current Loop Supply Voltage XTR VS Signal Converter and Supply Sensor Signal Conditioning Sensor Signal Receivers: VS=I*R X RCV1 RCV2 Signal Current Output RCV n jm-Sept 05

  4. XTR 4 to 20mA Current LoopSupply Voltage • Supply Voltage nominal 24V • Min: +12V (sometimes as low as +7V) • Max: +36V (short time over-voltage +40V) Power supply for the XTR and the Sensor is derived from the minimum current <4mA (<3.4mA) and the sub-regulated supply voltage. jm-Sept 05

  5. XTR 4 to 20mA Current LoopStandard Specification • Signal Current Range: 4.0 to 20.0mA • Error Signaling Range: 3.4 to 4mA and 20 to 24mA These under and over ranges are used to indicate error conditions of the sensor: wire break, short, over-load, excitation failure. There is a “NAMUR” specification, which specifies these special ranges. jm-Sept 05

  6. XTR 4 to 20mA Current LoopPower Dissipation • Power dissipation of the XTR is calculated from the voltage across the XTR and the current flowing. • Examples: 24Vsupply – (20mA*500W) = 14V P = 14V * 20mA = 280mW 36Vsupply – (20mA*50W) = 35V P = 35V * 20mA = 700mW We use an external power transistor to get the heat out of the IC. jm-Sept 05

  7. XTR 4 to 20mA Current LoopCircuit Protection Protection against harsh industrial environment: + Supply XTR Signal Out jm-Sept 05

  8. XTR 4 to 20mA Current LoopWhy “Current” Constant current generates a constant voltage across a “Shunt” resistor • Insensitive to wire resistance • Insensitive to multiple receivers (shunts) • Insensitive to conducted noise • Easy signal filtering • Low cost wiring ( just 2 wires) • Used in Industry since many years It will remain STANDARD for many years, because: • Lower cost than digital signal transmission • Better noise immunity • Longer distance ( >1km) jm-Sept 05

  9. XTR 4 to 20mA Current LoopHART Protocol • HART is a digital protocol which can be modulated onto the 4 to 20mA signal wires. • It is used where remote sensor programming is required (“Smart Sensor”) • HART puts several restrictions to the wiring, wire length, shunt resistance and supply voltage. jm-Sept 05

  10. 3-Wire Connection Supply Voltage XTR Signal Converter (and Supply) Signal Sensor Signal Conditioning Sensor Signal Receiver jm-Sept 05

  11. XTR Current or Voltage Transmitter • Many sensors are connected via 3 Wires: +Supply, GND, Signal Do not mix with the 2-wire 4 to 20mA current loop ! Popular signals for these active sensors are: “V” 0 to +10V, 0 to +5V “I” 0 to +20mA ( 24mA ), 4 to 20mA ( 3.4 to 24mA ) The current signal is compatible to the “4 to 20mA current loop” signals. jm-Sept 05

  12. XTR +24V Output Disable Output Failure I-Mirror Reg. Out DRV - SENSE + VREF I1 Signal Input IOUT + - 0 to 20mA (4 to 20mA) GND IOUT = VIN/RSET * 10 RSET IOUT= 10*I1 3-Wire Current Transmitter • XTR110 (“old” product) • XTR111 ( New Product in planning !) • External Resistor R1 allowsflexible setup to a wide range of output currents. • Supply max : 44V, nominal: 24V. • Supply min: < 9V • Current compliance stretches well below GND ( external transistor) • I1 defined by ext. R1. I2 = 10 * I1 • Regulator output: <5mA • Package: DFN-10 [3x3mm] • Internet Price: $1.45 (@1kpcs) • RTM: Q2 2006 jm-Sept 05

  13. “XTR” + OPA - 3-Wire Voltage TransmitterDiscrete solution Supply Voltage (PGA309 ...) Signal Sensor Signal Conditioning Sensor Signal Receiver Driver Op Amp (and Supply) R2 1k R1 1k jm-Sept 05

  14. “XTR” 3-wire TransmitterCurrent or Voltage Outputdigitally selectable Supply Voltage (PGA309 ...) Signal Sensor Signal Conditioning XTR300 Sensor Signal Receiver XTR300 and Supply jm-Sept 05

  15. Normal 2-Wire Operation of XTR115 Input Signals & Feedback Voltage, VR2, referenced to Iret Feedback Voltage, VR2 is negative with reference to Iret Op Amp Circuit Loop Gain forces A1+ = A1- = Iret = 0V IIN = VIN / RIN + Vref / Roffset IR1 = IIN IIN * R1 = VR2 VR2 = Iout / R2, Op Amp Loop Controls Iout to Create VR2 Iout = VR2 /R2 tg-Sept 05

  16. 3-Wire 4-20mA NOTfor XTR115 (or any 2-Wire XTR!) Current cannot flow through R2 in the right direction to create 0V at A1+ (Need VR2 to be negative referenced to Iret) T1 drives current into ground at Iout over-current limit of 41mA No current though RL !! tg-Sept 05

  17. 4-20mA Transmitter Design Solutions • 2-Wire General Purpose • 3-Wire General Purpose • 4-20mA Current Loop Receiver • 2-Wire RTD Conditioners • with Linearization • 2-Wire Bridge Sensor Conditioners • with Linearization • 2-Wire RTD Conditioner • with Digital Cal (Linearization, Span, Offset) tg-Sept 05

  18. 2-Wire General Purpose tg-Sept 05

  19. XTR115 / XTR116 tg-Sept 05

  20. 3-Wire General Purpose XTR110 tg-Sept 05

  21. 4-20mA Current Loop Receiver tg-Sept 05

  22. 2-Wire RTD Conditioner with Linearization tg-Sept 05

  23. 2-Wire Bridge Sensor Conditioner with Linearization tg-Sept 05

  24. 2-Wire RTD Conditioner with Digital Cal for Linearization, Span, Offset tg-Sept 05

  25. RTD IN & 4-20mA OUT w/Digital Calibration tg-Sept 05

  26. XTR108 Key Features • 10Ω to 10kΩ RTD Conditioner • RTD Compensation • Offset, Span, NonLinearity • 0.1% Post-Calibration Accuracy • -40°C to +85°C Range • Loop Voltage: 7.5V to 40V • SPI Interface Digital Calibration/Configuration • 6 Channel Input Mux • Allows for up to 5 different Zero set points • Internal/External VREF • Undedicated Spare Op Amp • Uses Standard External SPI 1k EEPROM (8-SOIC Package) • Can be used in 3-Wire 4-20mA systems (Voltage Out Mode) • 5.1V Sub-Regulated Output • SSOP-24 Package • $3.35 @1k tg-Sept 05

  27. XTR108EVM & Development Tools XTR108EVM Control/Program Software XTR108 Resistor Selection Tool XTR108EVM User’s uide XTR108 QuickStart Guide Detailed, Step-by-Step System Calibration “Definition by Example” tg-Sept 05

  28. New & ImprovedXTR108EVM Voltage Output Mode Enhancement Calibration Accuracy to <0.1% Low Noise Hardware Design • Evaluate XTR108 with your RTD • Software Calibration/Control for XTR108 • Available NOW! tg-Sept 05

  29. XTR108 Modification for 3-Wire Voltage (or Current) OutputXTR108: PTC [PT10 – PT10000]Sensor Front-End VOUT See NEW data sheet for details (page25) jm-Sept 05

  30. XTR117, 4-20mA Transmitter Key Benefits Features • High Accuracy: Low Span & Offset Errors • Easily interfaced with sensors or circuitry • Simple Over-Scale signaling • Regulated 5V power for External Circuitry • Minimal power consumption: 250µA • Wide Operating Voltage range: +7.5V to +40V • Tolerant of power supply surges up to +50V • Gain of 100x to reduce noise sensitivity • Miniature MSOP-8 package • $0.90USD @ 1k Qty • Accuracy without calibration • Noise resistant signaling • Robust in harsh electrical environments • A generous 3.75mA available for sensor circuitry • Requires minimal board space • Unbeatable: Cost/Size/Performance benefits Applications • Pressure Transducers • Temperature Transducers • Humidity Transducers • Industrial Process Monitors • PGA309 4-20mA Output Converter (Convert Voltage-Out to Current-Out) tg-Sept 05

  31. Complete 4-20mA Sensor ConditionerDigital Calibration of Sensor Linearity, Span, Offset, TempcosPGA308 & XTR117 tg-Sept 05

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