Part # AD693 datasheet

Part Manufacturer: Analog Devices

Analog Devices

Part Description: AD693 Loop-Powered 4-20 mA Sensor Transmitter

Part Details:

a Loop-Powered 4­20 mA Sensor Transmitter AD693 FEATURES FUNCTIONAL BLOCK DIAGRAM Instrumentation Amplifier Front EndLoop-Powered OperationPrecalibrated 30 mV or 60 mV Input SpansIndependently Adjustable Output Span and ZeroPrecalibrated Output Spans: 4­20 mA Unipolar 0­20 mA Unipolar12 8 mA Bipolar Precalibrated 100 RTD Interface 6.2 V Reference with Up to 3.5 mA of Current AvailableUncommitted Auxiliary Amp for Extra FlexibilityOptional External Pass Transistor to Reduce Self-Heating Errors PRODUCT DESCRIPTION PRODUCT HIGHLIGHTS The AD693 is a monolithic signal conditioning circuit which 1. The AD693 is a complete monolithic low-level voltage-to- accepts low-level inputs from a variety of transducers to control a current loop signal conditioner. standard 4­20 mA, two-wire current loop. An on-chip voltage 2. Precalibrated output zero and span options include reference and auxiliary amplifier are provided for transducer 4­20 mA, 0­20 mA, and 12 ± 8 mA in two- and three-wire excitation; up to 3.5 mA of excitation current is available when the configurations. device is operated in the loop-powered mode. Alternatively, thedevice may be locally powered for three-wire applications when 3. Simple resistor programming adds a continuum of ranges 0­20 mA operation is desired. to the basic 30 mV and 60 mV input spans. Precalibrated 30 mV and 60 mV input spans may be set by 4. The common-mode range of the signal amplifier input simple pin strapping. Other spans from 1 mV to 100 mV may extends from ground to near the device s operating voltage. be realized with the addition of external resistors. The auxiliary 5. Provision for transducer excitation includes a 6.2 V amplifier may be used in combination with on-chip voltages to reference output and an auxiliary amplifier which may be provide six precalibrated ranges for 100 RTDs. Output span configured for voltage or current output and signal and zero are also determined by pin strapping to obtain the amplification. standard ranges: 4­20mA, 12 ± 8 mA and 0­20 mA. 6. The circuit configuration permits simple linearization of Active laser trimming of the AD693 s thin-film resistors result bridge, RTD, and other transducer signals. in high levels of accuracy without the need for additional 7. A monitored output is provided to drive an external pass adjustments and calibration. Total unadjusted error is tested on transistor. This feature off-loads power dissipation to every device to be less than 0.5% of full scale at +25°C, and less extend the temperature range of operation, enhance than 0.75% over the industrial temperature range. Residual reliability, and minimize self-heating errors. nonlinearity is under 0.05%. The AD693 also allows for the useof an external pass transistor to further reduce errors caused by 8. Laser-wafer trimming results in low unadjusted errors and self-heating.

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AD693.pdf Datasheet