AD693AE

回路供电4.20毫安传感变送器 Loop-Powered 4.20 mA Sensor Transmitter

Product Details

The AD693 is a monolithic signal conditioning circuit which accepts low-level inputs from a variety of transducers to control a standard 4-20 mA, two-wire current loop. An on-chip voltage reference and auxiliary amplifier are provided for transducer excitation; up to 3.5 mA of excitation current is available when the device is operated in the loop-powered mode. Alternatively, the device may be locally powered for three-wire applications when 0-20 mA operation is desired.

Precalibrated 30 mV and 60 mV input spans may be set by simple pin strapping. Other spans from 1 mV to 100 mV may be realized with the addition of external resistors. The auxiliary amplifier may be used in combination with on-chip voltages to provide six precalibrated ranges for 100 ohm RTDs. Output span and zero are also determined by pin strapping to obtain the standard ranges: 4-20mA, 12 ± 8 mA and 0-20 mA.

Active laser trimming of the AD693"s thin-film resistors result in high levels of accuracy without the need for additional adjustments and calibration. Total unadjusted error is tested on every device to be less than 0.5% of full scale at +25°C, and less than 0.75% over the industrial temperature range. Residual nonlinearity is under 0.05%. The AD693 also allows for the use of an external pass transistor to further reduce errors caused by self-heating.

For transmission of low-level signals from RTDs, bridges and pressure transducers, the AD693 offers a cost-effective signal conditioning solution. It is recommended as a replacement for discrete designs in a variety of applications in process control, factory automation and system monitoring.

The AD693 is packaged in a 20-pin ceramic side-brazed DIP, 20-pin Cerdip, and 20-pin LCCC and is specified over the -40°C to +85°C industrial temperature range.

### Features and Benefits

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Instrumentation Amplifier Front End

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Loop-Powered Operation

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Independently Adjustable Output Span and Zero

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Precalibrated Output Spans:

4-12 mA Unipolar

0-20 mA Unipolar

12 ± 8mA Bipolar

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Precalibrated 20 mV or 60mV Input Spans

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Precalibrated 100 O RTD Interface

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6.2 V Reference with Up to 3.5 mA of Current Available

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Uncommitted Auxiliary Amp for Extra Flexibility

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Optional External Pass Transistor to Reduce Self-Heating Errors