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AD694:  4-20mA Monolithic Current Transmitter

Product Details

The AD694 is a monolithic current transmitter that accepts high level signal inputs to drive a standard 4-20 mA current loop for the control of valves, actuators, and other devices commonly used in process control. The input signal is buffered by an input amplifier that can be used to scale the input signal or buffer the output from a current mode DAC. Precalibrated input spans of 0 V to 2 V and 0 V to 10 V are selected by simple pin strapping; other spans may be programmed with external resistor.

The output stage compliance extends to within 2 V of VS and its special design allows the output voltage to extend below common in dual supply operation. An alarm warns of an open 4-to-20 mA loop or noncompliance of the output stage.

Active laser trimming of the AD694's thin film resistors results in high levels of accuracy without the need for additional adjustments and calibration. An external pass transistor may be used with the AD694 to off-load power dissipation, extending the temperature range of operation.

The AD694 is the ideal building block for systems requiring noise immune 4-20 mA signal transmission to operate valves, actuators, and other control devices, as well as for the transmission of process parameters such as pressure, temperature, or flow. It is recommended as a replacement for discrete designs in a variety of applications in industrial process control, factory automation, and system monitoring.

The AD694 is available in hermetically sealed, 16-pin cerdip and plastic SOIC, specified over the -40°C to +85°C industrial temperature range, and in a 16-pin plastic DIP, specified over the 0°C to +70°C temperature range.


  • 4-20 mA, 0-20 mA Output Ranges
  • Precalibrated Input Ranges: 0V to 2V, 0V to 10V
  • Precision Voltage Reference Programmable to 2.000 V or 10.000 V
  • Single or Dual Supply Operation
  • Wide Power Supply Range: 4.5V to 36V
  • Wide Output Compliance
  • Input Buffer Amplifier
  • Open-Loop Alarm
  • Optional External Pass Transistor to Reduce Self-Heating Errors
  • 0.002% Typ Nonlinearity

Functional Block Diagram for AD694

AD694 Diagram
Functional Block Diagram for AD694


Title Content Type File Type
AD694: 4 - 20 mA Transmitter Data Sheet  (Rev B, 08/2002) (pdf, 208 kB) Data Sheets PDF
A Designer's Guide to Instrumentation Amplifiers (3rd Edition) Design Handbooks HTML
Auto-Zero Amplifiers  (doc, 75 kB)
A wide variety of electronic applications, especially those involving very small input signals, require signal paths with very low offset voltage and offset voltage drift over time and temperature.
Technical Articles DOC
High-performance Adder Uses Instrumentation Amplifiers
Make an adder circuit using instrumentation amplifiers to increase input impedance.
(EDN, 9/3/2009)
Technical Articles HTML
Applying Instrumentation Amplifiers Effectively: The Importance of an Input Ground Return  (pdf, 508 kB) Technical Documentation PDF
Leading Inside Advertorials: Applying Instrumentation Amplifiers Effectively–The Importance of an Input Ground Return  (pdf, 121 kB) Overview PDF
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary 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

AD694 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
AD694AQ Status: Production 16 ld CerDIP 16 Ind Tube, 25 $10.04 $8.61 N  Material Info PCN Purchase
AD694ARZ Status: Production 16 ld SOIC - Wide 16 Ind Tube, 47 $6.70 $5.59 Y  Material Info PCN Purchase
AD694BQ Status: Production 16 ld CerDIP 16 Comm. Tube, 25 $12.81 $10.81 N  Material Info PCN Purchase
AD694BRZ Status: Production 16 ld SOIC - Wide 16 Ind Tube, 47 $10.71 $9.00 Y  Material Info PCN Purchase
AD694JNZ Status: Production 16 ld PDIP 16 Comm. Tube, 25 $7.28 $6.14 Y  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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