Texas Instruments INA281EVM User manual

1
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
User's Guide
SBOU244–June 2020
INA281EVM
This user’s guide describes the characteristics, operation, and use of the INA281 evaluation module
(EVM). This EVM is designed to evaluate the performance of the INA281 voltage-output, current shunt
monitor in a variety of configurations. Throughout this document, the terms evaluation board, evaluation
module, and EVM are synonymous with the INA281EVM. This document also includes a schematic,
reference printed-circuit board (PCB) layouts, and a complete bill of materials (BOM).
Trademarks
All trademarks are the property of their respective owners.

WARNING
General Texas Instruments High Voltage Evaluation (TI HV EVM) User Safety Guidelines www.ti.com
2SBOU244–June 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
INA281EVM
1 General Texas Instruments High Voltage Evaluation (TI HV EVM) User Safety Guidelines
Always follow TI’s setup and application instructions, including use of all interface components within their
recommended electrical rated voltage and power limits. Always use electrical safety precautions to help
ensure your personal safety and those working around you. Contact TI's Product Information Center
http://support/ti./com for further information.
Save all warnings and instructions for future reference.
WARNING
Failure to follow warnings and instructions may result in personal injury,
property damage or death due to electrical shock and burn hazards.
The term TI HV EVM refers to an electronic device typically provided as an open framed, unenclosed
printed circuit board assembly. It is intended strictly for use in development laboratory environments,
solely for qualified professional users having training, expertise and knowledge of electrical safety risks in
development and application of high voltage electrical circuits. Any other use and/or application are strictly
prohibited by Texas Instruments. If you are not suitable qualified, you should immediately stop from further
use of the HV EVM.
1. Work Area Safety
a. Keep work area clean and orderly.
b. Qualified observer(s) must be present anytime circuits are energized.
c. Effective barriers and signage must be present in the area where the TI HV EVM and its interface
electronics are energized, indicating operation of accessible high voltages may be present, for the
purpose of protecting inadvertent access.
d. All interface circuits, power supplies, evaluation modules, instruments, meters, scopes and other
related apparatus used in a development environment exceeding 50Vrms/75VDC must be
electrically located within a protected Emergency Power Off EPO protected power strip.
e. Use stable and nonconductive work surface.
f. Use adequately insulated clamps and wires to attach measurement probes and instruments. No
freehand testing whenever possible.
2. Electrical Safety
As a precautionary measure, it is always a good engineering practice to assume that the entire EVM
may have fully accessible and active high voltages.
a. De-energize the TI HV EVM and all its inputs, outputs and electrical loads before performing any
electrical or other diagnostic measurements. Revalidate that TI HV EVM power has been safely
de-energized.
b. With the EVM confirmed de-energized, proceed with required electrical circuit configurations,
wiring, measurement equipment connection, and other application needs, while still assuming the
EVM circuit and measuring instruments are electrically live.
c. After EVM readiness is complete, energize the EVM as intended.
WARNING
While the EVM is energized, never touch the EVM or its electrical
circuits, as they could be at high voltages capable of causing electrical
shock hazard.

www.ti.com General Texas Instruments High Voltage Evaluation (TI HV EVM) User Safety Guidelines
3
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
3. Personal Safety
a. Wear personal protective equipment (for example, latex gloves or safety glasses with side shields)
or protect EVM in an adequate lucent plastic box with interlocks to protect from accidental touch.
Limitation for safe use:
EVMs are not to be used as all or part of a production unit.

Overview www.ti.com
4SBOU244–June 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
INA281EVM
2 Overview
The INA281 device is a voltage-output, high-side and low-side measurement, current sense amplifier with
an enable pin in a very-small SOT-23 package. As shown in Table 1, the INA281 has gains that range
from 20 V/V to 500 V/V, depending on the gain option selected. The voltage developed across the device
inputs is amplified by the corresponding gain of the specific device, and is presented at the output pin. The
device accurately senses voltage drops across shunts at common-mode voltages from –4 V to +110 V,
independent of supply voltages. The device survives common-mode voltages from –20 V to +120 V. The
device operates with supply voltages between 2.7 V and 20 V, and draws a typical of 1.7 mA at room
temperature.
Table 1. INA281 Gain Option Summary
Product Gain (V/V)
INA281A1 and INA281B1 20
INA281A2 and INA281B2 50
INA281A3 and INA281B3 100
INA281A4 and INA281B4 200
INA281A5 and INA281B5 500
2.1 EVM Kit Contents
Table 2 summarizes the contents of the INA281EVM kit. Contact the Texas Instruments Product
Information Center nearest you if any component is missing. TI also recommends checking the INA281
device product folder at www.ti.com for any further information regarding this product.
Table 2. INA281EVM Kit Contents
Item Item Part Number Quantity
INA281EVM test board INA281EVM 1
2.2 Related Documentation From Texas Instruments
This document provides information regarding Texas Instruments' integrated circuits used in the assembly
of the INA281EVM.
Table 3. Related Documentation
Document Literature Number
INA281 product data sheet SBOSA29
INA281-Q1 product data sheet SBOSA01

www.ti.com Hardware
5
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
3 Hardware
The INA281EVM provides basic functional evaluation of the INA281. The fixture layout is not intended to
be a model for the target circuit, nor is it laid out for electromagnetic compatibility (EMC) testing. The
INA281EVM consists of one PCB with an option to cut out ten individual PCBs, one for each of the five
gain options (1 to 5) and the two different pin outs (A and B) listed in Table 1. Be aware that because of
the different pinouts of the A and B versions, the layouts and test point locations are also different. Each of
the PCB cutouts consists of one INA281Xn device (where Xis A or B and nis 1, 2, 3, 4, or 5), and test
points and sockets for external hardware connections, as well as pads to solder down optional circuitry.
3.1 Features
The INA281EVM PCB provides the following features:
• Evaluation of all gain options through provided device boards
• Ease of access to device pins with test points
• Pads and sockets for optional filtering at the input pins and output pin
• Multiple input signal options, including a method to solder a shunt resistor (2512) and safely measure
current up to 5 A.
See the device data sheet for comprehensive information about the INA281 and the available gain
options.

Operation www.ti.com
6SBOU244–June 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
INA281EVM
4 Operation
4.1 Quick Start Setup
Follow these procedures to set up and use one of the panels of the INA281EVM. For the following
instructions, X is pinout A or B, and n is gain option 1, 2, 3, 4, or 5.
Step 1. Choose the desired gain option panel and pin out variation.
Step 2. Connect an external dc supply voltage (between 1.7 V and 20 V) to a VS test point, and
connect the ground reference of that supply to a GND test point on the same panel.
Step 3. Provide a differential input voltage signal to the Vin+ and Vin– nodes by connecting the signal
leads to the J1_Xn pin 1 and J1_Xn pin 2 on the EVM, as explained in Section 4.2. The
INA281 is a unidirectional current-sensing device because there is no reference pin;
therefore, the device can only measure current in one direction.
4.2 Measurements
The INA281EVM allows the user to either emulate the voltage developed across a sense resistor based
on a given set of system conditions, or to connect the device inputs to an external shunt. Optionally, a
surface-mount technology (SMT) shunt resistor can be soldered across the Vin+ and Vin– pads, and these
inputs can be connected in series with the external system and load.
To configure a measurement evaluation without a the onboard shunt resistor, follow this procedure:
1. Connect a positive differential voltage across the Vin+ (J1_Xn) and Vin– (J1_Xn) tabs. Given the
internal GND reference of the device, make sure that the Vin+ pin is the more positive of the two
inputs.
2. Additionally, if the differential voltage supply is a floating supply, connect a –4-V to 110-V common-
mode voltage to the inputs by connecting the positive lead of the external voltage source to the
Vin– (J1_Xn) tab, and source ground to a GND test point. This action effectively raises the absolute
common-mode voltage of the input pins, while still retaining a positive input differential signal.
3. If an external shunt is being used make the connections such that the sensing location is across the
shunt and there will be no high current on the sensing path. See Getting Started with TI Precision
Labs - Current Sense Amplifiers: Shunt Resistor Layout
4. Measure the output voltage at the Vout test point with respect to GND.
To configure a measurement evaluation with a shunt resistor, follow this procedure:
1. Solder a 2512 resistor at the R1_Xn pads that connects the Vin+ (J1_Xn) and Vin– (J1_Xn) inputs.
2. Connect the Vin+ (J1_Xn) and Vin– (J1_Xn) tabs in series with the load and bus voltage sources
while powered off.
WARNING
If measuring current, first make sure that the equipment (shunt
resistor, wires, connectors, and so on) can support the
amperage and power dissipation. Secondly, make sure that the
current flowing through J1 does not exceed 5 A. Failure to do so
can result in hot surfaces (> 55°C), damage to the EVM, or
personal injury.
3. Power on the system and measure the output voltage at the Vout test point. Vout is equal to the
gain of the device multiplied by the differential voltage measured directly at the device input pins.

www.ti.com EVM Components
7
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
5 EVM Components
This section summarizes the INA281EVM components. For the following instructions, X is pinout A or B,
and n is gain option 1, 2, 3, 4, or 5.
5.1 R2_Xn, R3_Xn, R4_Xn, C2_Xn, C3_Xn
R2_Xn, R3_Xn, R4_Xn, are factory-installed 0-Ω0603 resistors.
C2_Xn, C3_Xn, are not populated.
Collectively, these pads allow for user-defined filters for the input pins (IN+ and IN–) and output pin (OUT)
of INA281. If a filter is desired, remove these resistors and replace them with > 0-ΩSMT resistors, and
populate the capacitor pads with capacitors. When using input filtering, take into account the input bias
current of the device.
5.2 C1_Xn
C1_Xn is a 0.1-µF, power-supply bypass capacitor.
5.3 R1_Xn
R1_Xn is unpopulated, but allows for a surface-mount shunt resistor to be soldered down between the
Vin+ and Vin– pads, which are sensed by IN+ and IN– input pins. If used, make sure R1_Xn has proper
power dissipation for the selected current load. The chosen resistor must have a 2512 footprint.
5.4 U1_Xn (INA281)
U1_Xn is the location for the INA281Xn test device.
The following list of factors are involved in selecting the appropriate device gain:
• The differential input voltage is either applied across the inputs or developed based on the load current
that flows through the shunt resistor.
• Make sure that the output voltage does not exceed the supply voltage. This limiting factor requires
attention to device selection.
• The selected device must allow the output voltage to remain within the acceptable range after the
developed input voltage is amplified by the respective device gain. The output voltage must remain
within the device-specified swing limitations for response in the linear range.
• An output below the minimum allowable output requires the selection of a device with a higher gain.
Likewise, an output above the maximum allowable output requires the selection of a device with a
lower gain.

Schematic, PCB Layout, and Bill of Materials www.ti.com
8SBOU244–June 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
INA281EVM
6 Schematic, PCB Layout, and Bill of Materials
NOTE: Board layouts are not to scale. These figures are intended to show how the board is laid out; they are not intended to be used for
manufacturing INA281EVM PCBs.
6.1 Schematics
Figure 1 shows the schematic of the INA281EVM for all gain versions for the A pinout. The difference is noted on the reference designator ending
in the gain option _An. Figure 2 shows the B1 gain panel and this is also a copy for all the other gain options with the reference designator ending
with the gain option _Bn.
Figure 1. INA281EVM Schematic: Gain A1 Panel

www.ti.com Schematic, PCB Layout, and Bill of Materials
9
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
Figure 2. INA281EVM Schematic: Gain B1 Panel

Schematic, PCB Layout, and Bill of Materials www.ti.com
10 SBOU244–June 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
INA281EVM
6.2 PCB Layout
Figure 3 through Figure 9 illustrate the PCB layout for the INA281EVM.
Figure 3. INA281EVM Top Overlay Figure 4. INA281EVM Bottom Overlay

www.ti.com Schematic, PCB Layout, and Bill of Materials
11
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
Figure 5. INA281EVM Top Layer Figure 6. INA281EVM Bottom Layer

Schematic, PCB Layout, and Bill of Materials www.ti.com
12 SBOU244–June 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
INA281EVM
Figure 7. INA281EVM Top Solder Figure 8. INA281EVM Bottom Solder

www.ti.com Schematic, PCB Layout, and Bill of Materials
13
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
Figure 9. INA281EVM Drill Drawing

Schematic, PCB Layout, and Bill of Materials www.ti.com
14 SBOU244–June 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
INA281EVM
6.3 Bill of Materials
Table 4 provides the parts list for the INA281EVM.
Table 4. Bill of Materials
Designator QTY Value Description Package Reference Part Number Manufacturer
C1_A1, C1_A2, C1_A3, C1_A4,
C1_A5, C1_B1, C1_B2, C1_B3,
C1_B4, C1_B5
10 0.1uF CAP, CERM, 0.1 uF, 25 V, +/- 10%, X7R, AEC-Q200 Grade 1,
0603 0603 CGA3E2X7R1E104K080A ATDK
H1_A1, H1_A2, H1_A3, H1_A4,
H1_A5, H1_B1, H1_B2, H1_B3,
H1_B4, H1_B5, H2_A1, H2_A2,
H2_A3, H2_A4, H2_A5, H2_B1,
H2_B2, H2_B3, H2_B4, H2_B5,
H3_A1, H3_A2, H3_A3, H3_A4,
H3_A5, H3_B1, H3_B2, H3_B3,
H3_B4, H3_B5, H4_A1, H4_A2,
H4_A3, H4_A4, H4_A5, H4_B1,
H4_B2, H4_B3, H4_B4, H4_B5
40 Bumpon, Cylindrical, 0.312 X 0.200, Black Black Bumpon SJ61A1 3M
J1_A1, J1_A2, J1_A3, J1_A4,
J1_A5, J1_B1, J1_B2, J1_B3,
J1_B4, J1_B5
10 Terminal Block, 3.5mm Pitch, 2x1, TH 7.0x8.2x6.5mm ED555/2DS On-Shore Technology
R2_A1, R2_A2, R2_A3, R2_A4,
R2_A5, R2_B1, R2_B2, R2_B3,
R2_B4, R2_B5, R3_A1, R3_A2,
R3_A3, R3_A4, R3_A5, R3_B1,
R3_B2, R3_B3, R3_B4, R3_B5,
R4_A1, R4_A2, R4_A3, R4_A4,
R4_A5, R4_B1, R4_B2, R4_B3,
R4_B4, R4_B5
30 0 RES, 0, 5%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 ERJ-3GEY0R00V Panasonic
TP1_A1, TP1_A2, TP1_A3,
TP1_A4, TP1_A5, TP1_B1,
TP1_B2, TP1_B3, TP1_B4,
TP1_B5, TP2_A1, TP2_A2,
TP2_A3, TP2_A4, TP2_A5,
TP2_B1, TP2_B2, TP2_B3,
TP2_B4, TP2_B5, TP3_A1,
TP3_A2, TP3_A3, TP3_A4,
TP3_A5, TP3_B1, TP3_B2,
TP3_B3, TP3_B4, TP3_B5,
TP4_A1, TP4_A2, TP4_A3,
TP4_A4, TP4_A5, TP4_B1,
TP4_B2, TP4_B3, TP4_B4,
TP4_B5
40 Test Point, Miniature, SMT Testpoint_Keystone_Miniature 5015 Keystone
U1_A1 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281A1IDBVR Texas Instruments
U1_A2 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281A2IDBVR Texas Instruments
U1_A3 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281A3IDBVR Texas Instruments
U1_A4 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281A4IDBVR Texas Instruments
U1_A5 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281A5IDBVR Texas Instruments
U1_B1 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281B1IDBVR Texas Instruments
U1_B2 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281B2IDBVR Texas Instruments

www.ti.com Schematic, PCB Layout, and Bill of Materials
15
SBOU244–June 2020
Submit Documentation Feedback Copyright © 2020, Texas Instruments Incorporated
INA281EVM
Table 4. Bill of Materials (continued)
Designator QTY Value Description Package Reference Part Number Manufacturer
U1_B3 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281B3IDBVR Texas Instruments
U1_B4 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281B4IDBVR Texas Instruments
U1_B5 1 INA281, -4-V to 110-V, 1.3-MHz Current-Sense Amplifier SOT23-5 INA281B5IDBVR Texas Instruments
C2_A1, C2_A2, C2_A3, C2_A4,
C2_A5, C2_B1, C2_B2, C2_B3,
C2_B4, C2_B5
0 0.1uF CAP, CERM, 0.1 uF, 25 V, +/- 10%, X7R, AEC-Q200 Grade 1,
0603 0603 CGA3E2X7R1E104K080A ATDK
C3_A1, C3_A2, C3_A3, C3_A4,
C3_A5, C3_B1, C3_B2, C3_B3,
C3_B4, C3_B5
0 100pF CAP, CERM, 100 pF, 50 V,+/- 10%, X7R, 0603 0603 CL10B101KB8NNNC Samsung Electro-Mechanics
FID1, FID2, FID3 0 Fiducial mark. There is nothing to buy or mount. N/A N/A N/A
R1_A1, R1_A2, R1_A3, R1_A4,
R1_A5, R1_B1, R1_B2, R1_B3,
R1_B4, R1_B5
0 0.01 RES, 0.01, 1%, 3 W, 2512 2512 CRA2512-FZ-R010ELF Bourns

IMPORTANT NOTICE AND DISCLAIMER
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE
DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY
IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD
PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable
standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you
permission to use these resources only for development of an application that uses the TI products described in the resource. Other
reproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third
party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims,
damages, costs, losses, and liabilities arising out of your use of these resources.
TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on
ti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable
warranties or warranty disclaimers for TI products.
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2020, Texas Instruments Incorporated