Vs = 4.75V to 5.5V

OUT

LMP8271

+

-

A1

GND

+IN

-IN

A2

GAIN = 2

A1

A2

100 k:

GAIN = 10

C1

I

PROPRIETARY

LEVEL-SHIFT

CIRCUITRY

OFFSET

OUT

LMP8271

+

-

A1

GND

+IN

- IN

PROPRIETARY

LEVEL-SHIFT

CIRCUITRY

A2

GAIN = 2

A1

A2

100 k:

GAIN = 10

10:

4 mA to 20 mA

CURRENT LOOP

C1

OFFSET

OBSOLETE

LMP8271

www.ti.com

SNOSAP6H – JUNE 2005 – REVISED APRIL 2013

CURRENT LOOP RECEIVER

Many types of process control instrumentation use 4 to 20 mA transmitters to transmit the sensor’s analog value

to a central control room. The LMP8271 can be used as a current loop receiver as shown in Figure 29.

Figure 29. Current Loop Receiver

HIGH SIDE CURRENT SENSING

High side current measurement requires a differential amplifier with gain. Here the DC voltage source represents

a common mode voltage with the +IN input at the supply voltage and the

−IN input very close to the supply

The LMP8271 can be used for high side current sensing. The large common mode voltage range of this device

allows it to sense signals outside of its supply voltage range. Also, the LMP8271 has very high CMRR, which

enables it to sense very small signals in the presence of larger common mode signals. The system in Figure 30

detected and amplified by the LMP8271 in the presence of a common mode signal of up to 16V with the highest

accuracy.

Figure 30. High Side Current Sensing

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