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 OPA388-Q1 is a unity-gain stable, precision operational amplifier 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 OPA388-Q1 is 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 OPA388-Q1 precision amplifier is 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 solution 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 solution.

+

+

±

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

OPA388-Q1

SBOS989 – AUGUST 2020

www.ti.com

18

Submit Document Feedback

Copyright © 2020 Texas Instruments Incorporated

Product Folder Links: OPA388-Q1