7 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.

7.1 Application Information

The OPAx397 is a unity-gain stable, precision operational amplifier family free from unexpected output and

phase reversal. The use of proprietary e-trim operational amplifier technology gives the benefit of low input

offset voltage over time and temperature, along with ultra-low input bias current. The OPAx397 are optimized

for full rail-to-rail input, allowing for low-voltage, single-supply operation or split-supply use. These miniature,

high-precision, low-noise amplifiers offer high-impedance inputs that have a common-mode range to the supply

rail, with low offset across the supply range, and a rail-to-rail output that swings within 5 mV of the supplies

under normal test conditions. The OPAx397 precision amplifiers are designed for upstream analog signal chain

applications in low or high gains, as well as downstream signal chain functions such as DAC buffering.

7.2 Typical Application

This single-supply, low-side, bidirectional current-sensing design example detects load currents from –1 A to

+1 A. The single-ended output spans from 110 mV to 3.19 V. This design uses the OPA397 because of the low

offset voltage and rail-to-rail input and output. One of the amplifiers is configured as a difference amplifier and

the other amplifier provides the reference voltage.

Figure 7-1 shows the schematic.

+

+

±

I

LOAD

V

BUS

V

OUT

V

CC

V

CC

V

REF

+

±

V

SHUNT

V

CC

U1A

U1B

R

4

R

SHUNT

R

1

R

3

R

L

R

5

R

6

R

2

Figure 7-1. Bidirectional Current-Sensing Schematic

OPA397, OPA2397, OPA4397

SBOSA02A – AUGUST 2021 – REVISED APRIL 2025

www.ti.com

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