Texas Instruments INA381EVM User manual

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INA381EVM
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User's Guide
SBOU196–December 2017
INA381EVM
This user’s guide describes the characteristics, operation, and use of the INA381 evaluation module
(EVM). This EVM is designed to evaluate the performance of the INA381A1, INA381A2, INA381A3, and
INA381A4 voltage output current-shunt monitors in a variety of configurations. The EVM also provides an
internal comparator with each of the above devices, and allows the user to define reference voltages for
each device’s alert function. Throughout this document, the terms evaluation board, evaluation module,
and EVM are synonymous with the INA381EVM. This document includes a schematic, reference printed-
circuit board (PCB) layouts, and a complete bill of materials (BOM).

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INA381EVM
Contents
1 Overview...................................................................................................................... 3
2 Hardware...................................................................................................................... 4
3 Quick Start Setup and Use ................................................................................................. 4
4 Circuitry ....................................................................................................................... 5
5 Schematics, PCB Layout, and Bill of Materials.......................................................................... 6
List of Figures
1 Schematic for A1 Device ................................................................................................... 6
2 Schematic for A2 Device ................................................................................................... 6
3 Schematic for A3 Device ................................................................................................... 7
4 Schematic for A4 Device ................................................................................................... 7
5 Top Overlay .................................................................................................................. 8
6 Top Layer..................................................................................................................... 8
7 Bottom Overlay............................................................................................................... 8
8 Bottom Layer ................................................................................................................. 8
List of Tables
1 INA381Ax Device Summary................................................................................................ 3
2 INA381EVM Kit Contents................................................................................................... 3
3 Related Documentation..................................................................................................... 3
4 Bill of Materials .............................................................................................................. 9

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INA381EVM
1 Overview
The INA381 family of current-shunt monitors (also called current-sense amplifiers) can sense voltage
drops across shunts at common-mode voltages from –0.3 V to +26 V, independent of the supply voltage.
Four fixed gains are available: 20 V/V, 50 V/V, 100 V/V, and 200 V/V. These devices operate from a
single 2.7-V to 5.5-V power supply, drawing a maximum of 1000 μA of supply current per amplifier
channel. A comparator is included to provide an active low alert signal when the output exceeds a user
defined voltage. The alert function operates in either continuous mode or latch mode to respectively
indicate whether a certain overvoltage or overcurrent event is occurring or has occurred. The INA381
devices are currently available in a 8-pin WSON surface-mount package with a thermal pad as the device
ground connection. Table 1 lists the available gain options.
Table 1. INA381Ax Device Summary
Product Gain
INA381A1 20 V/V
INA381A2 50 V/V
INA381A3 100 V/V
INA381A4 200 V/V
1.1 Kit Contents
Table 2 lists the contents of the INA381EVM kit. Contact the nearest Texas Instruments Product
Information Center if any component is missing. TI highly recommends checking the INA381 family
product folder on the TI website at www.ti.com for further information regarding this product.
Table 2. INA381EVM Kit Contents
Item Quantity
INA381EVM Test Board 1
1.2 Related Documentation From Texas Instruments
The following document provides information regarding TI's integrated circuits used in the assembly of the
INA381EVM. This user's guide is available from the TI website under literature number SBOU196. Any
letter appended to the literature number corresponds to the document revision that is current at the time of
the writing of this document. Newer revisions are available from www.ti.com or the Texas Instruments'
Literature Response Center at [phone] or the Product Information Center at [phone]. When
ordering, identify the document by both title and literature number.
Table 3. Related Documentation
document Literature Number
INA381 product data sheet SBOS848

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INA381EVM
2 Hardware
The INA381 is an op amp current-sense solution that provides ease of use and high performance. The
INA381EVM is intended to provide basic functional evaluation of this device family. 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 INA381EVM consists of one PCB with an option to snap apart into four individual
PCBs; one for each of the four devices (INA381A1, INA381A2, INA381A3, and INA381A4).
2.1 Features
The layout of the INA381EVM printed-circuit board (PCB) is designed to provide the following features:
• Evaluation of all gain options for the INA381Ax
• Ease of access to device pins with test points
• Capability to evaluate high-side and low-side configurations
• Ability to set the comparator trip voltage.
See the INA381 data sheet for comprehensive information about the INA381 family of devices.
3 Quick Start Setup and Use
The following are instructions to set up and use the INA381 devices of the INA381EVM. For the following
instructions, x = A to D.
Step 1. Connect ground reference of that supply to the GND test point TPx1 or TPxV1 and connect
an external dc supply voltage between 2.7 V and 5.5 V to the Vs test point TPx2 or TPxV2.
Step 2. Connect the input per Section 3.1.
3.1 Measurements
The INA381EVM enables the user to either simulate the voltage developed across a sense resistor based
on a given set of system conditions or to connect remotely to an existing shunt already included in an
example application.
The following procedures are used to configure a measurement evaluation without a shunt. For the
following instructions, x = A to D.
Step 1. Stack a floating differential voltage supply on top of a common mode voltage by connecting
the ground of the floating differential voltage supply to the positive voltage output of the
common mode voltage supply. Adjust common mode voltage to any value between –0.2 V
and +26 V; the data sheet condition is 12 V.
Step 2. Connect the positive polarity of the differential voltage to IN+ (TPx3 or TPxV3) and the
negative polarity to IN– (TPx5 or TPxV5) test points. (IN+ pin must be the more positive of
the two inputs.)
Step 3. Measure the output voltage at the VOUT test point (TPx4 or TPxV4).
NOTE: The output voltage is equal to the gain of the device multiplied by the differential voltage
measured directly at the device input pins.
3.2 Alert Function
The INA381EVM provides an alert pin that will pull low when the output exceeds a user-defined voltage.
With the alert function, there are two different modes: latch mode and continuous mode. The device enters
latch mode when RESET (pin 4) is pulled to VS+ (pin 2). When reset is pulled to GND (bottom pad) the
device enters continuous mode and resets the device if it is latched and the output voltage is below
CMPREF (pin 5). CMPREF determines at what voltage the ALERT pin goes low. This value is
conveniently adjustable to any voltage between GND and VS+ with the onboard potentiometer. When the
voltage on VOUT exceeds the voltage of CMPREF, the onboard LED turns on.

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INA381EVM
4 Circuitry
This section summarizes the INA381EVM components. For the following instructions, x = A to D.
4.1 Cx1, Cx2
Cx1 and Cx2 are 10-μF and 0.1-μF supply bypass capacitors respectively.
4.2 Cx3, Rx2, Rx4
Cx3, Rx2, and Rx4 footprints are for customizing the input pi-filter to the INA381 device. Default values
are 0 Ωand 1000 pF. However, no capacitor is installed.
4.3 Cx4, Rx3
Cx4 and Rx3 are footprints for a customizable output filter. Default values are 0 Ωand 1000 pF. However,
no capacitor is installed.
4.4 Ux1
Ux1 is the test-device location. Four device boards are supplied with the INA381EVM. Each board is
populated with one of the available device gains: 20 V/V, 50 V/V, 100 V/V, or 200 V/V. This option enables
users to test the devices and determine the gain setting best suited for a given application. The following
list of factors is involved in selecting the appropriate device:
• Select INA381 for unidirectional applications only.
• The differential input voltage is applied across the inputs, or developed based on the load current that
flows through the shunt resistor connected across the inputs.
• The most limiting factor that requires attention to be given to device selection is the output voltage.
• The selected device must allow the output voltage to remain within the acceptable range after the
Vsense voltage (IN+ – IN–) is amplified by the respective device gain. The max output voltage must
remain within the range of 10 mV above ground to 100 mV below the supply voltage.
• Choose an appropriate gain and sense resistor to create the largest appropriate output swing possible
and to minimize error.
4.5 Rx5, Cx5
Rx5 is a 50-kΩtrimming potentiometer that allows the user to set the CMPREF voltage without having to
use an additional power supply. Cx5 is a bypass capacitor that is meant to absorb any transients that
would otherwise feed into the CMPREF pin.
4.6 Rx1, Rx7, Qx1, Dx1
Rx1 serves as a pull-up resistor that keeps the ALERT pin voltage around VS+ when the ALERT pin is
open drain (inactive) and as an impedance path that prevents VS+ from shorting to GND when the ALERT
pin goes low (active). Qx1 serves as a switch controlled by the ALERT pin. When Qx1 switches on
(ALERT goes active low), Dx1 turns on, which notifies the user that voltage at VOUT exceeded the
voltage at CMPREF. Rx7 limits the current through Dx1.
4.7 Jx
Jx controls whether the device uses continuous mode or latch mode. RST shorted to VS+ puts the device
in latch mode. RST shorted to GND puts the device in continuous mode.
4.8 Voltages Inputs
The IN+ (TPx3 or TPxV3) and IN– (TPx5 or TPxV5) inputs accept a differential voltage that is amplified by
the selected device gain and is presented at the VOUT test point (TPx04 or TPx14). These inputs can
also be used to connect the differential voltage developed across an external shunt in an existing circuit.
The acceptable differential input voltage range and polarity are determined by the supply voltage and gain
of the selected device.

QB1
RB2
12
DB1
1000pF
CB3
DNP
RB4
VCCB
0.1µF
CB2
GND
TPB2
TPB1
10µF
CB1
0
RB6
0
RB3
1000pF
CB4
DNP
GND
10.0k
RB1
GND
GND
VCCB
TPB4
VOUT
TPBV1
TPBV2
TPBV4
VOUT
VS+
2
VOUT 7
CMPIN
6GND 9
RESET 4
ALERT 3
IN-
8
IN+
1
CMPREF
5
INA381A2DSG
UB1
1
2
3
JB
TPB3
IN+
TPB5
IN-
RB5
3312J-1-503E
GND
TPB6
CMPREF
1000pF
CB5
TPBV6
TPBV3
IN+
TPBV5
IN-
2.05k
RB7
VCCD
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VS+
2
VOUT 7
CMPIN
6GND 9
RESET 4
ALERT 3
IN-
8
IN+
1
CMPREF
5
UA1
INA381A1DSG
QA1
TPA3
IN+ 0
RA2
DA1
1000pF
CA3DNP
0
RA4
TPA5
IN-
VCCA
0.1µF
CA2
GND
TPA2
TPA1
10µF
CA1
0
RA6
0
RA3
1000pF
CA4
DNP
GND
10.0k
RA1
GND
GND
VCCA
TPA4
VOUT
RA5
3312J-1-503E
GND
TPA6
CMPREF
1000pF
CA5
TPAV6
TPAV1
TPAV2
TPAV3
IN+
TPAV5
IN-
TPAV4
VOUT
1
2
3
JA
2.05k
RA7
VCCC
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INA381EVM
5 Schematics, 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.
The figures are not intended to be used for manufacturing INA381EVM PCBs.
5.1 Schematics
Figure 1 through Figure 4 shows the schematics for the INA381EVM A1, A2, A3, and A4 devices,
respectively.
Figure 1. Schematic for A1 Device
Figure 2. Schematic for A2 Device

GND
QD1
0
RD2
12
DD1
1000pF
CD3DNP
0
RD4
VCCD
0.1µF
CD2
GND
TPD2
TPD1
10µF
CD1
0
RD6
0
RD3
1000pF
CD4
DNP
GND
10.0k
RD1
GND
GND
VCCD
TPD4
VOUT
TPDV1
TPDV2
TPDV4
VOUT
VS+
2
VOUT 7
CMPIN
6GND 9
RESET 4
ALERT 3
IN-
8
IN+
1
CMPREF
5
INA381A4DSG
UD1
1
2
3
JD
TPD3
IN+
TPD5
IN-
RD5
3312J-1-503E
GND
TPD6
CMPREF
1000pF
CD5
TPDV6
TPDV3
IN+
TPDV5
IN-
2.05k
RD7
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GND
GND
QC1
0
RC2
12
DC1
1000pF
CC3
DNP
0
RC4
VCCC
0.1µF
CC2
GND
TPC2
TPC1
10µF
CC1
0
RC6
0
RC3
1000pF
CC4DNP
GND
10.0k
RC1
GND
GND
VCCC
TPC4
VOUT
TPCV1
TPCV2
TPCV4
VOUT
VS+
2
VOUT 7
CMPIN
6GND 9
RESET 4
ALERT 3
IN-
8
IN+
1
CMPREF
5
INA381A3DSG
UC1
1
2
3
JC
TPC3
IN+
TPC5
IN-
RC5
3312J-1-503E
GND
TPC6
CMPREF
1000pF
CC5
TPCV6
TPCV3
IN+
TPCV5
IN-
2.05k
RC7
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GND
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INA381EVM
Figure 3. Schematic for A3 Device
Figure 4. Schematic for A4 Device

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INA381EVM
5.2 PCB Layout
Figure 5 through Figure 8 illustrate the PCB layers of the INA381EVM.
Figure 5. Top Overlay
Figure 6. Top Layer
Figure 7. Bottom Overlay
Figure 8. Bottom Layer

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INA381EVM
5.3 Bill of Materials
Table 4 provides the parts list for the INA381EVM.
Table 4. Bill of Materials
Designator Quantity Value Description Package Reference Part Number Manufacturer
CA1, CB1, CC1, CD1 4 10uF CAP, CERM, 10 µF, 16 V,+/- 20%, X7R, 0805 0805 EMK212BB7106MG-T Taiyo Yuden
CA2, CB2, CC2, CD2 4 0.1uF CAP, CERM, 0.1 µF, 16 V,+/- 10%, X7R, 0603 0603 C0603C104K4RACTU Kemet
CA5, CB5, CC5, CD5 4 1000pF CAP, CERM, 1000 pF, 50 V, +/- 10%, X7R,
0603 0603 C0603C102K5RACTU Kemet
DA1, DB1, DC1, DD1 4 Green LED, Green, SMD LED_0805 APT2012LZGCK Kingbright
H1, H2, H3, H4, H5, H6, H7, H8,
H9, H10, H11, H12, H13, H14,
H15, H16
16 Bumpon, Hemisphere, 0.25 X 0.075, Clear 75x250 mil SJ5382 3M
JA, JB, JC, JD 4 Header, 1.27mm, 3x1, Gold, SMT Header, 1.27mm, 3x1,
SMT GRPB031VWTC-RC Sullins Connector Solutions
QA1, QB1, QC1, QD1 4 -50V MOSFET, P-CH, -50 V, -0.13 A, SOT-23 SOT-23 BSS84-7-F Diodes Inc.
RA1, RB1, RC1, RD1 4 10.0k RES, 10.0 k, 1%, 0.1 W, 0603 0603 RC0603FR-0710KL Yageo America
RA2, RA3, RA4, RA6, RB2, RB3,
RB4, RB6, RC2, RC3, RC4, RC6,
RD2, RD3, RD4, RD6
16 0 RES, 0, 5%, 0.1 W, 0603 0603 RC0603JR-070RL Yageo America
RA5, RB5, RC5, RD5 4 50k TRIMMER, 50k ohm, 0.1 W, SMD 2.5x2.8mm 3312J-1-503E Bourns
RA7, RB7, RC7, RD7 4 2.05k RES, 2.05 k, 1%, 0.1 W, 0603 0603 RC0603FR-072K05L Yageo America
SH-J1, SH-J2, SH-J3, SH-J4 4 Mini Shunt, Closed Top, 650 V AC, -45 to 85
degC, Pitch 1.27 mm, Height 3 mm, RoHS Mini Shunt, Body 2.5x1.27mm, Height 3mm NPB02SVAN-RC Sullins Connector Solutions
TPA1, TPA2, TPA3, TPA4, TPA5,
TPA6, TPB1, TPB2, TPB3, TPB4,
TPB5, TPB6, TPC1, TPC2, TPC3,
TPC4, TPC5, TPC6, TPD1, TPD2,
TPD3, TPD4, TPD5, TPD6
24 Test Point, Miniature, SMT Testpoint_Keystone_Miniat
ure 5015 Keystone
UA1 1 20V/V 26-V, Low Cost, Zero-Drift, Voltage-Output,
Current-Shunt Monitor With Integrated
Comparator, DSG0008A (WSON-8)
DSG0008A INA381A1DSG Texas Instuments
UB1 1 50V/V 26-V, Low Cost, Zero-Drift, Voltage-Output,
Current-Shunt Monitor With Integrated
Comparator, DSG0008A (WSON-8)
DSG0008A INA381A2DSG Texas Instuments
UC1 1 100V/V 26-V, Low Cost, Zero-Drift, Voltage-Output,
Current-Shunt Monitor With Integrated
Comparator, DSG0008A (WSON-8)
DSG0008A INA381A3DSG Texas Instuments
UD1 1 200V/V 26-V, Low Cost, Zero-Drift, Voltage-Output,
Current-Shunt Monitor With Integrated
Comparator, DSG0008A (WSON-8)
DSG0008A INA381A4DSG Texas Instuments

STANDARD TERMS FOR EVALUATION MODULES
1. Delivery: TI delivers TI evaluation boards, kits, or modules, including any accompanying demonstration software, components, and/or
documentation which may be provided together or separately (collectively, an “EVM” or “EVMs”) to the User (“User”) in accordance
with the terms set forth herein. User's acceptance of the EVM is expressly subject to the following terms.
1.1 EVMs are intended solely for product or software developers for use in a research and development setting to facilitate feasibility
evaluation, experimentation, or scientific analysis of TI semiconductors products. EVMs have no direct function and are not
finished products. EVMs shall not be directly or indirectly assembled as a part or subassembly in any finished product. For
clarification, any software or software tools provided with the EVM (“Software”) shall not be subject to the terms and conditions
set forth herein but rather shall be subject to the applicable terms that accompany such Software
1.2 EVMs are not intended for consumer or household use. EVMs may not be sold, sublicensed, leased, rented, loaned, assigned,
or otherwise distributed for commercial purposes by Users, in whole or in part, or used in any finished product or production
system.
2Limited Warranty and Related Remedies/Disclaimers:
2.1 These terms do not apply to Software. The warranty, if any, for Software is covered in the applicable Software License
Agreement.
2.2 TI warrants that the TI EVM will conform to TI's published specifications for ninety (90) days after the date TI delivers such EVM
to User. Notwithstanding the foregoing, TI shall not be liable for a nonconforming EVM if (a) the nonconformity was caused by
neglect, misuse or mistreatment by an entity other than TI, including improper installation or testing, or for any EVMs that have
been altered or modified in any way by an entity other than TI, (b) the nonconformity resulted from User's design, specifications
or instructions for such EVMs or improper system design, or (c) User has not paid on time. Testing and other quality control
techniques are used to the extent TI deems necessary. TI does not test all parameters of each EVM.
User's claims against TI under this Section 2 are void if User fails to notify TI of any apparent defects in the EVMs within ten (10)
business days after delivery, or of any hidden defects with ten (10) business days after the defect has been detected.
2.3 TI's sole liability shall be at its option to repair or replace EVMs that fail to conform to the warranty set forth above, or credit
User's account for such EVM. TI's liability under this warranty shall be limited to EVMs that are returned during the warranty
period to the address designated by TI and that are determined by TI not to conform to such warranty. If TI elects to repair or
replace such EVM, TI shall have a reasonable time to repair such EVM or provide replacements. Repaired EVMs shall be
warranted for the remainder of the original warranty period. Replaced EVMs shall be warranted for a new full ninety (90) day
warranty period.
3Regulatory Notices:
3.1 United States
3.1.1 Notice applicable to EVMs not FCC-Approved:
FCC NOTICE: This kit is designed to allow product developers to evaluate electronic components, circuitry, or software
associated with the kit to determine whether to incorporate such items in a finished product and software developers to write
software applications for use with the end product. This kit is not a finished product and when assembled may not be resold or
otherwise marketed unless all required FCC equipment authorizations are first obtained. Operation is subject to the condition
that this product not cause harmful interference to licensed radio stations and that this product accept harmful interference.
Unless the assembled kit is designed to operate under part 15, part 18 or part 95 of this chapter, the operator of the kit must
operate under the authority of an FCC license holder or must secure an experimental authorization under part 5 of this chapter.
3.1.2 For EVMs annotated as FCC – FEDERAL COMMUNICATIONS COMMISSION Part 15 Compliant:
CAUTION
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not
cause harmful interference, and (2) this device must accept any interference received, including interference that may cause
undesired operation.
Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to
operate the equipment.
FCC Interference Statement for Class A EVM devices
NOTE: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of
the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is
operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction manual, may cause harmful interference to radio communications.
Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to
correct the interference at his own expense.