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Tuesday, April 7, 2009

4-20mA Current-Loop Transmitter Circuit



The XTR117 is a precision current output converter designed
to transmit analog 4-20mA signals over an industry-standard
current loop. It provides accurate current scaling and output
current limit functions.

The on-chip voltage regulator (5V) can be used to power
external circuitry. A current return pin (IRET) senses any
current used in external circuitry to assure an accurate
control of the output current.

FEATURES
_ LOW QUIESCENT CURRENT: 130 uA
_ 5V REGULATOR FOR EXTERNAL CIRCUITS
_ LOW SPAN ERROR: 0.05%
_ LOW NONLINEARITY ERROR: 0.003%
_ WIDE-LOOP SUPPLY RANGE: 7.5V to 40V
_ MSOP-8 AND DFN-8 PACKAGES


0-5V To 4-20mA Current-Loop Transmitter Circuit


The AM422 is a low cost monolithic voltage–
to–current converter specially designed for
analog signal transmission. The AM422 is
available in a 3– or 2–wire version, which allows
applications with flexible input voltage
ranges to be used for a standard output current.
Output current range and current offset level
are freely adjustable by external resistors. The
IC consists of three basic sections: an operational
amplifier input stage for single ended
input signals (0.5–4.5V, 0–10V, or other), a
programmable 4.5 to 10V reference for transducer
excitation, and a current output, freely
adjustable in a wide current range (4–20mA,
0–20mA, other). With the broad spectrum of
possible input signals the AM422 is a flexible
and multipurpose voltage–to–current converter
for single ended transducers or voltage transmission.

FEATURES
- Wide Supply Voltage Range: 6...35V
- Wide Operating Temperature Range: –40°C...+85°C
- Adjustable Voltage Reference:4.5 to 10V
- Operational Amplifier Input:0.5...4.5V, 0...5V, other
- Adjustable Offset Current
- Available as Three– (0/4...20mA) or Two–Wire Version (4...20mA)
- Adjustable Output Current Range
- Protection Against Reverse Polarity
- Protected Current Output

AM422 datasheet pdf

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