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 OPAx388-Q1 are unity-gain stable, precision operational amplifiers free from unexpected output and phase

reversal. The use of proprietary zero-drift circuitry gives the benefit of low input offset voltage over time and

temperature, as well as lowering the 1/f noise component. As a result of the high PSRR, these devices work

well in applications that run directly from battery power without regulation. The OPAx388-Q1 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 100 mV beyond

the supplies without input crossover distortion and a rail-to-rail output that swings within 5 mV of the supplies

under normal test conditions. The OPAx388-Q1 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.

8.2 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 OPA388-Q1 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 8-1 shows the circuit drawing.

+

+

±

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 8-1. Bidirectional Current-Sensing

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OPA388-Q1, OPA2388-Q1

SBOS989A – AUGUST 2020 – REVISED NOVEMBER 2021

Copyright © 2021 Texas Instruments Incorporated

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Product Folder Links: OPA388-Q1 OPA2388-Q1