a 420 mA Transmitter AD694 FUNCTIONAL BLOCK DIAGRAM FEATURES 420 mA, 020 mA Output Ranges Precalibrated Input Ranges: 0 V to 2 V, 0 V to 10 V Precision Voltage Reference Programmable to 2.000 V or 10.000 V Single or Dual Supply Operation Wide Power Supply Range: 4.5 V to 36 V Wide Output Compliance Input Buffer Amplifier Open-Loop Alarm Optional External Pass Transistor to Reduce Self-Heating Errors 0.002% Typ Nonlinearity PRODUCT DESCRIPTION PRODUCT HIGHLIGHTS The AD694 is a monolithic current transmitter that accepts 1. The AD694 is a complete voltage in to 420 mA out current high level signal inputs to drive a standard 420 mA current transmitter. loop for the control of valves, actuators, and other devices com- 2. Pin programmable input ranges are precalibrated at 0 V to monly used in process control. The input signal is buffered by 2 V and 0 V to 10 V. an input amplifier that can be used to scale the input signal or 3. The input amplifier may be configured to buffer and scale the buffer the output from a current mode DAC. Precalibrated in- input voltage, or to serve as an output amplifier for current put spans of 0 V to 2 V and 0 V to 10 V are selected by simple output DACs. pin strapping other spans may be programmed with external 4. The output voltage compliance extends to within 2 V of the resistors. positive supply and below common. When operated with a The output stage compliance extends to within 2 V of V and S 5 V supply, the output voltage compliance extends 30 V be- its special design allows the output voltage to extend below low common. common in dual supply operation. An alarm warns of an open 5. The AD694 interfaces directly to 8-, 10-, and 12-bit single 420 mA loop or noncompliance of the output stage. supply CMOS and bipolar DACs. Active laser trimming of the AD694s thin film resistors results 6. The 4 mA zero current may be switched on and off with a in high levels of accuracy without the need for additional adjust- TTL control pin, allowing 020 mA operation. ments and calibration. An external pass transistor may be used 7. An open collector alarm warns of loop failure due to open with the AD694 to off-load power dissipation, extending the temperature range of operation. wires or noncompliance of the output stage. 8. A monitored output is provided to drive an external pass The AD694 is the ideal building block for systems requiring transistor. The feature off-loads power dissipation to extend noise immune 420 mA signal transmission to operate valves, the temperature range of operation and minimize self-heating actuators, and other control devices, as well as for the transmis- error. sion 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 40C to +85C industrial temperature range, and in a 16-pin plastic DIP, specified over the 0C to +70C temperature range. REV. B Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. use, nor for any infringements of patents or other rights of third parties that Tel: 781/329-4700 www.analog.com may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781/326-8703 Analog Devices, Inc., 2002AD694* PRODUCT PAGE QUICK LINKS Last Content Update: 02/23/2017 COMPARABLE PARTS DESIGN RESOURCES View a parametric search of comparable parts. AD694 Material Declaration PCN-PDN Information DOCUMENTATION Quality And Reliability Data Sheet Symbols and Footprints AD694: 4 - 20 mA Transmitter Data Sheet DISCUSSIONS Technical Books A Designer s Guide to Instrumentation Amplifiers, 3rd View all AD694 EngineerZone Discussions. Edition, 2006 SAMPLE AND BUY REFERENCE MATERIALS Visit the product page to see pricing options. Technical Articles Auto-Zero Amplifiers TECHNICAL SUPPORT High-performance Adder Uses Instrumentation Amplifiers Submit a technical question or find your regional support number. DOCUMENT FEEDBACK Submit feedback for this data sheet. This page is dynamically generated by Analog Devices, Inc., and inserted into this data sheet. A dynamic change to the content on this page will not trigger a change to either the revision number or the content of the product data sheet. This dynamic page may be frequently modified.