RG

12.4 k

-

+

INA188

15 V

15 V

REF

VOUT = 2.5 V ± 2.3 V

REF3225

5 V

100 k

4.87 k

20

±10 V

4 mA to 20 mA

±20 mA

2.5 V

10 F

27

INA188

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SBOS632 – SEPTEMBER 2015

Product Folder Links: INA188

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Copyright © 2015, Texas Instruments Incorporated

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The INA188 measures a small differential voltage with a high common-mode voltage developed between the

noninverting and inverting input. The low offset drift in conjunction with no 1/f noise makes the INA188 suitable

for a wide range of applications. The ability to set the reference pin to adjust the functionality of the output signal

offers additional flexibility that is practical for multiple configurations.

8.2 Typical Application

Figure 55 shows the basic connections required for operating the INA188. Applications with noisy or high-

impedance power supplies may require decoupling capacitors close to the device pins. The output is referred to

the output reference (REF) pin that is normally grounded. The reference pin must be a low-impedance

connection to assure good common-mode rejection.

Figure 55. PLC Input (±10 V, 4 mA to 20 mA)

8.2.1 Design Requirements

For this application, the design requirements are:

•

4-mA to 20-mA input with less than 20-

Ω burden

•

±20-mA input with less than 20-

Ω burden

•

±10-V input with impedance of approximately 100 k

Ω

•

Maximum 4-mA to 20-mA or ±20mA burden voltage equal to ±0.4 V

•

Output range within 0 V to 5 V