Texas Instruments INA901EVM-CVAL User manual

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INA901EVM-CVAL Evaluation Module User's Guide
User's Guide
SBOU216A–October 2018–Revised June 2020
INA901EVM-CVAL Evaluation Module User's Guide
This user’s guide describes the characteristics, operation, and use of the INA901EVM-CVAL evaluation
module (EVM). This EVM is designed to evaluate the performance of the INA901-SP 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 INA901EVM-CVAL. This document also includes a
schematic, reference printed-circuit board (PCB) layouts, and a complete bill of materials (BOM).
WARNING
Danger: HIGH VOLTAGE! This evaluation board is intended for
professional use only. It has exposed high voltages. Do not
operate this board without proper high-voltage/high-current safety
practices. Read the General Texas Instruments High Voltage
Evaluation (TI HV EVM) User Safety Guidelines section before using
the EVM.

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Contents
1 General Texas Instruments High Voltage Evaluation (TI HV EVM) User Safety Guidelines ...................... 3
2 Overview...................................................................................................................... 4
2.1 INA901-SP Overview............................................................................................... 4
2.2 INA901EVM-CVAL Overview ..................................................................................... 4
2.3 EVM Kit Contents................................................................................................... 4
2.4 Related Documentation From Texas Instruments.............................................................. 4
3 Hardware...................................................................................................................... 5
3.1 Features.............................................................................................................. 5
4 Operation ..................................................................................................................... 5
4.1 Warnings............................................................................................................. 5
4.2 Quick Start Setup................................................................................................... 5
4.3 Measurements ...................................................................................................... 6
5 EVM Components.......................................................................................................... 10
5.1 Input Current....................................................................................................... 10
5.2 Input Filter Options................................................................................................ 10
5.3 First Order and Sallen Key Filter Options ..................................................................... 10
5.4 Comparator......................................................................................................... 10
5.5 Unused Comparator Channel and Best Practices ............................................................ 10
5.6 Comparator Disconnect .......................................................................................... 10
6 Schematic, PCB Layout, and Bill of Materials.......................................................................... 11
6.1 INA901EVM-CVAL Schematics ................................................................................. 11
6.2 PCB Layer Plots................................................................................................... 12
6.3 Bill of Materials .................................................................................................... 16
List of Figures
1 High-Side Setup Using Onboard Shunt Resistor ....................................................................... 7
2 High-Side Setup Using An External Shunt Resistor .................................................................... 8
3 Supply Setup for Common and Differential Voltage .................................................................... 9
4 INA901EVM-CVAL Schematic ........................................................................................... 11
5 INA901EVM-CVAL Top Overlay ......................................................................................... 12
6 INA901EVM-CVAL Top Copper.......................................................................................... 13
7 INA901EVM-CVAL Bottom Copper...................................................................................... 14
8 INA901EVM-CVAL Bottom Overlay...................................................................................... 15
List of Tables
1 INA901EVM-CVAL Kit Contents........................................................................................... 4
2 INA901EVM-CVAL Bill of Materials ..................................................................................... 16
Trademarks
All trademarks are the property of their respective owners.

WARNING
www.ti.com General Texas Instruments High Voltage Evaluation (TI HV EVM) User Safety Guidelines
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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.

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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.
2 Overview
2.1 INA901-SP Overview
The INA901-SP is a space-grade, radiation-hardness-assured (RHA) current-sense amplifier. It can sense
drops across shunt resistors at common-mode voltages from –15 V to +65 V, independent of the supply
voltage. The INA901-SP operates from a single +2.7-V to +16-V supply, drawing 700 μA (typical) of supply
current. The voltage output has a gain of 20 V/V with a typical gain error of ±0.2%. The device is specified
over the extended operating temperature range of –55°C to +125°C, QML-V qualified and is offered in an
8-pin CFP package.
2.2 INA901EVM-CVAL Overview
The INA901EVM-CVAL is designed to demonstrate the functionality and performance of the INA901-SP.
The board contains a footprint for a size 2512 surface mount shunt resistor. It can also be operated with
an external shunt resistor or by simply applying differential voltages to the inputs.
The board also comes equipped with a space-grade LM193AJRLQMLV-SP dual comparator, which is
used to configure the EVM as an over current detector.
2.3 EVM Kit Contents
Table 1 summarizes the contents of the INA901EVM-CVAL kit. Contact the Texas Instruments Product
Information Center nearest you if any component is missing. TI also recommends checking the INA901
device product folder at www.ti.com for any further information regarding this product.
Table 1. INA901EVM-CVAL Kit Contents
Item Item Part Number Quantity
INA901EVM-CVAL Test Board INA901EVM-CVAL 1
2.4 Related Documentation From Texas Instruments
This document provides information regarding Texas Instruments' integrated circuits used in the assembly
of the INA901EVM-CVAL.
Document Literature Number
INA901 Product Data Sheet SBOS938

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3 Hardware
The EVM is user configurable so that a wide range of operating conditions and filtering options can be
demonstrated. The board also contains an LM193AJRLQMLV-SP space-grade comparator so that the
EVM can be evaluated as an overcurrent detector. The board can support –15-V to 65-V common-mode
signal on the inputs, and a 10-A load current with a user installed shunt resistor.
3.1 Features
• Flexible input connections, including both onboard and external shunt
• Ease of access to device pins with test points
• Onboard comparator for out-of-box overcurrent detection
• Footprints for optional filtering at the input pins
4 Operation
4.1 Warnings
4.1.1 High Voltage
The common-mode voltage rating of the INA901-SP and the INA901EVM-CVAL is –15 V to 65 V. When
using the device and EVM under such circumstances, all proper safety practices must be followed. Do not
apply less than –15 V or more than 65 V.
4.1.2 High Current
An unpopulated footprint is provided for the user to install an onboard shunt resistor. The shunt resistor
traces have a maximum current rating of 10 A. Ensure that the power rating of the resistor is sufficient for
the application.
4.1.3 Board Component Grades
All components on this board are intended for evaluation purposes only and not for flight.
4.2 Quick Start Setup
Follow these procedures to set up and use the INA901EVM-CVAL:
Step 1. Connect the positive lead of an external DC supply voltage to J2 (V+), and connect the
ground reference of that supply to J3 (GND). Set the supply for 5 V. Ensure this supply is
turned off for now.
Step 2. Ensure the shorting plug is populated at J5. Alternatively, a separate pullup voltage can be
applied to the comparator. To do this, depopulate the shorting plug at J5, and apply the
desired voltage to J6 (V_PULLUP).
Step 3. Provide a differential input voltage signal to the IN+ and IN– nodes by connecting the signal
leads to the positive and negative terminals of J1 on the EVM, respectively, as explained in
Section 4.3.

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4.3 Measurements
WARNING
CAUTION HOT SURFACE! 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 10 A.
Failure to do so can result in hot surfaces (> 55°C), damage to the
EVM, or personal injury.
The shunt resistor will become hot during use. Ensure proper
precautions are taken to prevent contact with R1 during operation.
Failure to do so can result in personal injury.

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To configure the EVM using an onboard shunt resistor, follow this procedure:
Step 1. Solder a size 2512 resistor at the pads of R1. Ensure the area is clean of flux, and the
chosen resistor is thermally capable of the desired use case.
Step 2. Connect the positive and negative terminals of J1 in series with the load and bus voltage
sources while powered off. You will need to ensure proper logical order to test either the
high-side, or low-side application. See TI Precision Labs - Current Sense Amplifiers: Design
Considerations for additional information on proper application and orientation. Figure 1
shows the correct connections for a high-side application using this method.
Figure 1. High-Side Setup Using Onboard Shunt Resistor
Step 3. Power on all supplies.
Step 4. Measure the output voltage at INA_OUT with respect to GND.
Step 5. Observe the overcurrent trigger: Using either a DMM or oscilloscope, measure the voltage at
CMP_OUT. Slowly increase the magnitude of the load current until it measures > 125 mV.
Observe the comparator output change states.

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To configure the EVM using an external shunt resistor, follow this procedure:
Step 1. Choose an external shunt for the desired use case. Ensure the chosen resistor is thermally
capable of the desired use case.
Step 2. Connect the positive and negative terminals of J1 with the load and bus voltage sources
while powered off. Figure 2 shows the correct connections for a high-side application using
this method. Ensure that you make the connections such that the sensing location is directly
across the shunt, and there will be no high current on the sensing path. See TI Precision
Labs - Current Sense Amplifiers: Shunt Resistor Layout for additional information.
Figure 2. High-Side Setup Using An External Shunt Resistor
Step 3. Power on all supplies.
Step 4. Measure the output voltage at INA_OUT with respect to GND using a DMM.
Step 5. Observe the overcurrent trigger: Using either a DMM or oscilloscope, measure the voltage at
CMP_OUT. Slowly increase the magnitude of the load current until it measures > 125 mV.
Observe the comparator output change states.

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To configure the EVM to evaluate a specific voltage use case, follow this procedure:
Step 1. Set the differential voltage: Connect an unpowered positive differential voltage across the
positive and negative terminals of J1. Given the internal GND reference of the device, make
sure that the IN+ pin is the more positive of the two inputs.
Step 2. Set the common mode voltage: to evaluate at a specific common mode, connect an
unpowered –15-V to 65-V voltage supply to the inputs by connecting the positive lead of the
external voltage source to the negative terminal of J1, and negative lead 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. Figure 3 shows how this supply setup should look
when this is done. Ensure that the supplies used to perform this are able to withstand the
voltages present before using this method.
Figure 3. Supply Setup for Common and Differential Voltage
Step 3. Power on all supplies.
Step 4. Measure the output voltage at INA_OUT with respect to GND using a DMM.
Step 5. Observe the overcurrent trigger: Using either a DMM or oscilloscope, measure the voltage at
CMP_OUT. Slowly increase the magnitude of the load current until it measures > 125 mV.
Observe the comparator output change states.

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5 EVM Components
This section summarizes the INA901EVM-CVAL components.
5.1 Input Current
J1 is the primary input terminal of the INA901EVM-CVAL. This terminal allows the EVM to be placed in
series with a bus voltage and load current. R1 is able to be fitted with a size 2512 resistor in this use case.
Alternatively, a differential voltage is able to be applied directly across the terminals of J1 to evaluate the
EVM.
5.2 Input Filter Options
Resistors R2 and R3, along with capacitor C3, form an optional filter on the inputs of the device. By
default, R2 and R3 are populated with 0-Ωresistors, and C3 is not populated. If this filter is populated, use
resistance of less than 10 Ωto minimize the introduction of additional errors.
C1 and C2 serve as additional options for common mode filtering on each input if desired. C1 and C2 are
not populated by default.
5.3 First Order and Sallen Key Filter Options
C5 is populated by default with a 15-pF capacitor which, along with the internal 96-kΩresistor at the PRE
OUT pin of U1, forms a first-order filter between the PRE OUT and BUF IN stages of U1.
By default, C6 is not populated, and R4 is populated with a 0-Ωresistor. These values may be changed
along with C5 to form a second order Sallen-Key filter. See the Device Functional Modes section of the
INA901-SP Radiation Hardened, –15-V to 65-V Common Mode Unidirectional Current-Shunt Monitor Data
Sheet for additional information on how to configure this.
5.4 Comparator
The "A" channel of comparator U2 is configured by default as an overcurrent detector. Resistors R6 and
R7 are configured by default so that the comparator reference is ½ of V+. As V+ also sets the full scale
output range of the INA901, this sets the overcurrent point of the comparator to ½ of the full scale output
range of the INA901, or when VSENSE > 125 mV for a supply voltage of 5 V. This set point can be changed
by adjusting the values of R6 and R7.
5.5 Unused Comparator Channel and Best Practices
The "B" channel of comparator U2 is unused by default. Resistors R8, R9, and R11 are configured in
accordance with the Unused Comparator Connections section of the Application Design Guidelines for
LM339, LM393, TL331 Family Comparators Including the New B-versions Application Report.
5.6 Comparator Disconnect
If the INA901 needs to be evaluated without other devices present, R5 can be depopulated to disconnect
the INA901 from the comparator.