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, as well as validating and testing their design

implementation to confirm system functionality.

8.1 Application Information

The OPAx992 family offers excellent DC precision and AC performance. These devices operate up to 40-V

supply rails and offer true rail-to-rail input/output, low offset voltage and offset voltage drift, as well as 10-MHz

bandwidth and high output drive. These features make the OPAx992 a robust, high-performance operational

amplifier for high-voltage industrial applications.

8.2 Typical Applications

8.2.1 Low-Side Current Measurement

Figure 8-1 shows the OPA992 configured in a low-side current sensing application. For a full analysis of the

circuit shown in Figure 8-1 including theory, calculations, simulations, and measured data, see TI Precision

Design TIPD129, 0-A to 1-A Single-Supply Low-Side Current-Sensing Solution.

V

CC

+

–

120

LOAD

I

LOAD

5.76 k

LM7705

5 V

V

OUT

R

SHUNT

R

F

R

G

OPA992

100 m

Figure 8-1. OPAx992 in a Low-Side, Current-Sensing Application

8.2.1.1 Design Requirements

The design requirements for this design are:

• Load current: 0 A to 1 A

• Output voltage: 4.9 V

• Maximum shunt voltage: 100 mV

8.2.1.2 Detailed Design Procedure

The transfer function of the circuit in Figure 8-1 is given in Equation 1:

OUT

LOAD

SHUNT

V

I

R

Gain

u

u

(1)

from 0 A to 1 A. To keep the shunt voltage below 100 mV at maximum load current, the largest shunt resistor is

defined using Equation 2:

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OPA992, OPA2992, OPA4992

SBOSA10 – JUNE 2021

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