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AD595:  Type K Thermocouple Amplifier with Cold Junction Compensation

Product Details

Newer Alternatives:
  • AD8495: 8-lead MSOP (lead-free) with 5mV/C output, single supply operation and improved accuracy for K type thermocouples.

The AD594/AD595 is a complete instrumentation amplifier and thermocouple cold junction compensator on a monolithic chip. It combines an ice point reference with a precalibrated amplifier to produce a high level (10 mV/°C) output directly from a thermocouple signal. Pin-strapping options allow it to be used as a linear amplifier-compensator or as a switched output setpoint controller using either fixed or remote setpoint control. It can be used to amplify its compensation voltage directly, thereby converting it to a stand-alone Celsius transducer with a low impedance voltage output.

The AD594/AD595 includes a thermocouple failure alarm that indicates if one or both thermocouple leads become open. The alarm output has a flexible format which includes TTL drive capability.

The AD594/AD595 can be powered from a single ended supply (including +5 V) and by including a negative supply, temperatures below 0°C can be measured. To minimize self-heating, an unloaded AD594/AD595 will typically operate with a total supply current 160 µA, but is also capable of delivering in excess of ±5 mA to a load.

The AD594 is precalibrated by laser wafer trimming to match the characteristic of type J (iron-constantan) thermocouples and the AD595 is laser trimmed for type K (chromel-alumel) inputs. The temperature transducer voltages and gain control resistors are available at the package pins so that the circuit can be recalibrated for the thermocouple types by the addition of two or three resistors. These terminals also allow more precise calibration for both thermocouple and thermometer applications.

The AD594/AD595 is available in two performance grades. The C and the A versions have calibration accuracies of ±1°C and ±3°C, respectively. Both are designed to be used from 0°C to +50°C, and are available in 14-pin, hermetically sealed, side-brazed ceramic DIPs as well as low cost cerdip packages.


  • Pretrimmed for Type J (AD594) or Type K (AD595) Thermocouples
  • Can Be Used with Type T Thermocouple Inputs
  • Low Impedance Voltage Output: 10 mV/°C
  • Built-In Ice Point Compensation
  • Wide Power Supply Range: +5 V to ±15 V
  • Low Power: <1 mW typical
  • Thermocouple Failure Alarm
  • Laser Wafer Trimmed to 1°C Calibration Accuracy
  • Setpoint Mode Operation
  • Self-Contained Celsius Thermometer Operation
  • High Impedance Differential Input
  • Side-Brazed DIP or Low Cost Cerdip

Typical Application Circuit for AD595


Title Content Type File Type
AD594/AD595: Monolithic Thermocouple Amplifiers With Cold Junction Compensation Data Sheet (Rev C, 12/1999) (pdf, 136 kB) Data Sheets PDF
AN-369: Thermocouple Signal Conditioning Using the AD594/AD595  (pdf, 108 kB)
This application note reviews thermocouple basics and illustrates circuit designs for thermocouple signal conditioning using the AD594/AD595.
Application Notes PDF
AN-274: Taking the Uncertainty Out of Thermocouple Temperature Measurement (With the AD594/AD595)  (pdf, 643 kB) Application Notes PDF
Design Techniques for reducing power consumption and harmful thermal events in industrial designs
This webcast will present: typical analog module configuration and show how to calculate the maximum ambient temperature that the system can tolerate, new technology to reduce the power dissipated in the module (regardless of what output load is connected), then look at the performance of these devices when the supply is run from a switching regulator rather than with a linear regulator.
Webcasts WEBCAST
ADT7301: Accurate, SPI-Compatible Temperature Sensor in SOT Package  (htm)
(analogZone September 1, 2003)
Product Reviews HTM
Selection Guide: Temperature Sensors  (pdf, 807 kB) Overview PDF
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD594/AD595 Thermocouple Conditioner
Calculates the input/output voltages from the AD594/AD595 based on thermocouple type, ambient temperature, and measured temperature.
Design Assistants HTML
AD594/AD595 Thermocouple Assistant
This tool will calculate output voltage based on thermocouple type and temperature for the AD594/AD595 thermocouple amplifiers.
Design Assistants HTML
This tool will calculate output voltage based on thermocouple type and temperature for the AD594/AD595 thermocouple amplifiers.
ADIsim Design/Simulation Tools HTML

Evaluation Kits & Symbols & Footprints

Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

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Price, packaging, availability

AD595 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
AD595ADZ Status: Production 14 ld Bottom-Brazed CerDIP 14 Ind Tube, 25 $26.27 $21.55 Y  Material Info PCN Purchase
AD595AQ Status: Production 14 ld CerDIP 14 Ind Tube, 25 $9.85 $8.34 N  Material Info PCN Purchase
AD595CDZ Status: Production 14 ld Bottom-Brazed CerDIP 14 Ind Tube, 25 $39.26 $32.62 Y  Material Info PCN Purchase
AD595CQ Status: Production 14 ld CerDIP 14 Ind Tube, 25 $16.15 $13.25 N  Material Info PCN Purchase
Price Table Help

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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