4-20mA Current Loop Receiver Circuit

4-20mA Current Loop Receiver with Input Overload
Protection circuit

The RCV420 is a precision current-loop receiver designed
to convert a 4–20mA input signal into a 0–5V
output signal. As a monolithic circuit, it offers high
reliability at low cost. The circuit consists of a premium
grade operational amplifier, an on-chip precision
resistor network, and a precision 10V reference. The
RCV420 features 0.1% overall conversion accuracy,
86dB CMR, and ±40V common-mode input range.

FEATURES
-COMPLETE 4-20mA TO 0-5V CONVERSION
- INTERNAL SENSE RESISTORS
-PRECISION 10V REFERENCE
- BUILT-IN LEVEL-SHIFTING
- ±40V COMMON-MODE INPUT RANGE
- 0.1% OVERALL CONVERSION ACCURACY
- HIGH NOISE IMMUNITY: 86dB CMR

A current-sensing circuit derives its power from the

4-20-mA current loop.

4-20mA Current Loop Receiver with fault protection and
digital-signal recovery circuit

Figure shows one form of flexible fault protection for the 24VDC
power supply of a 4-20mA loop. Also included is circuitry for recovering
a digital signal superimposed on that loop. U1 (a high-side current-
sense amplifier with comparator and reference) senses the loop current
in R1 as an 8-40mV voltage and amplifies it by 100, producing an
output-voltage range of 0.8V to 4V. That output (VOUT) can directly
drive external meters, strip-chart recorders, and A/D converter inputs.

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