Part # AD694 datasheet

Part Manufacturer: Analog Devices

Analog Devices

Part Description: AD694 420 mA Transmitter Data Sheet (REV.B)


Part Details:

a 4­20 mA Transmitter AD694* FEATURES FUNCTIONAL BLOCK DIAGRAM 4­20 mA, 0­20 mA Output RangesPrecalibrated Input Ranges: 0 V to 2 V, 0 V to 10 VPrecision Voltage Reference Programmable to 2.000 V or 10.000 VSingle or Dual Supply OperationWide Power Supply Range: 4.5 V to 36 VWide Output ComplianceInput Buffer AmplifierOpen-Loop AlarmOptional External Pass Transistor to Reduce Self-Heating Errors0.002% 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 externalresistors. 4. The output voltage compliance extends to within 2 V of the positive supply and below common. When operated with a The output stage compliance extends to within 2 V of VS and 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 open4­20 mA loop or noncompliance of the output stage. 5. The AD694 interfaces directly to 8-, 10-, and 12-bit single supply CMOS and bipolar DACs. Active laser trimming of the AD694 s thin film resistors resultsin high levels of accuracy without the need for additional adjust- 6. The 4 mA zero current may be switched on and off with a ments and calibration. An external pass transistor may be used TTL control pin, allowing 0­20 mA operation. with the AD694 to off-load power dissipation, extending the 7. An open collector alarm warns of loop failure due to open temperature range of operation. wires or noncompliance of the output stage. The AD694 is the ideal building block for systems requiring 8. A monitored output is provided to drive an external pass noise immune 4­20 mA signal transmission to operate valves, transistor. The feature off-loads power dissipation to extend actuators, and other control devices, as well as for the transmis- the temperature range of operation and minimize self-heating sion of process parameters such as pressure, temperature, or error. flow. It is recommended as a replacement for discrete designs ina variety of applications in industrial process control, factoryautomation, and system monitoring. The AD694 is available in hermetically sealed, 16-pin CERDIPand plastic SOIC, specified over the ­40°C to +85°C industrialtemperature range, and in a 16-pin plastic DIP, specified overthe 0°C to +70°C temperature range. *Protected by U.S. Patents: 30,586; 4,250,445; 4,857,862. REV. B Information furnished by Analog Devices is believed to be accurate andreliable. However, no responsibility is assumed by Analog Devices for itsuse, nor for any infringements of patents or other rights of third parties that One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. may result from its use. No license is granted by implication or otherwise


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AD694.pdf Datasheet