8.2.2 4-mA to 20-mA Loop Design

Factory automation systems commonly use the 4-mA to 20-mA (4-20 mA) communication protocol to enable

process automation. In typical 2-wire, 4-mA to 20-mA loop applications, power to the remote transmitter is

limited to less than 4 mA total consumption. As a result of the power limitations, low power consumption is

essential. The OPA396 solves many design challenges in 4-mA to 20-mA loop applications, where low power,

high accuracy, and high bandwidth are required.

+

+

OPA396

+

OPA396

11.3 kŸ

11.3 kŸ

14.3 kŸ

14.3 kŸ

12 nF

12 nF

102.4 kŸ

102.4 kŸ

Ÿ

Ÿ

Ÿ

Ÿ

Ÿ

Ÿ

1.98 kŸ

1.98 kŸ

DAC

I

OUT+

I

OUT±

5 V

4.096 V

Figure 8-4. 4-20 mA Loop Interface Schematic

8.2.2.1 Design Requirements

Table 8-1. Design Parameters

PARAMETER

VALUE

Total current consumption

< 100 μA

DAC control voltage

0 V to 4.096 V

Output current

4 mA to 20 mA

8.2.2.2 Application Curve

Time (1 ms/div)

-4

0

-3

4

-2

8

-1

12

0

16

1

20

2

24

3

28

4

32

5

36

6

40

7

44

8

48

C050

Figure 8-5. 4-mA to 20-mA Loop Response

OPA396

SBOSA65 – JULY 2021

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