OPA388_17 Datasheet, PDF (18/34 Pages) Texas Instruments – Precision, Zero-Drift, Zero-Crossover, True Rail-to-Rail Input/Output, Operational Amplifiers

OPA388, OPA2388, OPA4388
SBOS777 – DECEMBER 2016
8 Application and Implementation
www.ti.com
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 OPAx388 is a unity-gain stable, precision operational amplifier family 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 family 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 OPAx388 series of precision amplifiers is suitable 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 OPAx388 because of its 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 41 shows the solution.
VCC
VREF
VCC
R5
U1B
+
VBUS
±
ILOAD
+
R1
VSHUNT
RSHUNT
±
R3
R2
+
U1A
VCC
R6
VOUT
RL
R4
Copyright © 2016, Texas Instruments Incorporated
Figure 41. Bidirectional Current-Sensing Schematic
18
Submit Documentation Feedback
Copyright © 2016, Texas Instruments Incorporated
Product Folder Links: OPA388 OPA2388 OPA4388