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.
|Title||Content Type||File Type|
|AD694: 4 - 20 mA Transmitter Data Sheet (Rev B, 08/2002) (pdf, 208 kB)||Data Sheets|
|A Designer's Guide to Instrumentation Amplifiers (3rd Edition)||Design Handbooks||HTML|
(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.
High-performance Adder Uses Instrumentation Amplifiers
Make an adder circuit using instrumentation amplifiers to increase input impedance.
|Applying Instrumentation Amplifiers Effectively: The Importance of an Input Ground Return (pdf, 508 kB)||Technical Documentation|
|Leading Inside Advertorials: Applying Instrumentation Amplifiers EffectivelyThe Importance of an Input Ground Return (pdf, 121 kB)||Overview|
|RAQs index||Rarely Asked Questions||HTML|
|Glossary of EE Terms||Glossary||HTML|
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.
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.