Texas Instruments INA191EVM User manual

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INA191EVM
User's Guide
SBOU218A–February 2019–Revised April 2019
INA191EVM
This user’s guide describes the characteristics, operation, and use of the INA191 evaluation module
(EVM). This EVM is designed to evaluate the performance of the INA191 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 INA191EVM. This document also includes a schematic,
reference printed-circuit board (PCB) layouts, and a complete bill of materials (BOM).

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INA191EVM
Contents
1 Overview...................................................................................................................... 3
1.1 EVM Kit Contents................................................................................................... 3
1.2 Related Documentation From Texas Instruments.............................................................. 3
2 Hardware ..................................................................................................................... 4
2.1 Features ............................................................................................................. 4
3 Operation ..................................................................................................................... 5
3.1 Quick Start Setup................................................................................................... 5
3.2 Measurements ...................................................................................................... 5
4 EVM Components ........................................................................................................... 6
4.1 R1x, R2x, R4x, R7x, R8x, C2x, C3x, C4x, C5x, C6x ......................................................... 6
4.2 C1x ................................................................................................................... 6
4.3 R3x ................................................................................................................... 6
4.4 R5x, R6x ............................................................................................................ 6
4.5 D1x, D2x, D3x, D4x, ............................................................................................... 6
4.6 S0x, S1x, S2x, S3x, S4x, S5x, S6x, S7x, S8x, S9x, S10x, S11x, S12x .................................... 6
4.7 U1x (INA191)........................................................................................................ 7
4.8 J0x, J1x .............................................................................................................. 7
5 Schematic, PCB Layout, and Bill of Materials ........................................................................... 8
5.1 Schematics .......................................................................................................... 8
5.2 PCB Layout ........................................................................................................ 14
5.3 Bill of Materials .................................................................................................... 16
List of Figures
1 INA191EVM Schematic: Gain A1 Panel ................................................................................. 9
2 INA191EVM Schematic: Gain A2 Panel ................................................................................ 10
3 INA191EVM Schematic: Gain A3 Panel ................................................................................ 11
4 INA191EVM Schematic: Gain A4 Panel ................................................................................ 12
5 INA191EVM Schematic: Gain A5 Panel ................................................................................ 13
6 INA191EVM Top Overlay ................................................................................................. 14
7 INA191EVM Bottom Overlay ............................................................................................. 14
8 INA191EVM Top Layer.................................................................................................... 14
9 INA191EVM Bottom Layer ............................................................................................... 14
10 INA191EVM Top Solder .................................................................................................. 14
11 INA191EVM Bottom Solder .............................................................................................. 14
12 INA191EVM Drill Drawing................................................................................................. 15
List of Tables
1 INA191 Gain Option Summary............................................................................................. 3
2 INA191EVM Kit Contents................................................................................................... 3
3 Related Documentation..................................................................................................... 3
4 Bill of Materials ............................................................................................................. 16
Trademarks
All trademarks are the property of their respective owners.

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INA191EVM
1 Overview
The INA191 device is a voltage-output, high- and low-side measurement current sense amplifier with an
enable pin in a very-small DSBGA package. As shown in Table 1, the INA191 has gains that range from
25 V/V to 500 V/V, depending on the gain option that is 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 –0.1 V to
40 V, independent of supply voltages. The device operates and survives common-mode voltages from
–0.3 V to +42 V. The device operates with supply voltages between 1.7 V and 5.5 V, and draws a
maximum of 65 µA at room temperature. The low offset of the zero-drift architecture enables sensing of
very-small differential input voltages, which helps widen the usable input dynamic range and minimize
power dissipation in the shunt resistor. Unlike many current sense amplifiers, the INA191 has a very low
input bias current, and thus, can easily measure microamps of current.
Table 1. INA191 Gain Option Summary
Product Gain (V/V)
INA191A1 25
INA191A2 50
INA191A3 100
INA191A4 200
INA191A5 500
1.1 EVM Kit Contents
Table 2 summarizes the contents of the INA191EVM kit. Contact the Texas Instruments Product
Information Center nearest you if any component is missing. TI also recommends checking the INA191
device product folder at www.ti.com for any further information regarding this product.
Table 2. INA191EVM Kit Contents
Item Item Part Number Quantity
INA191EVM test board INA191EVM 1
Quick Connect Receptacle 10-12AWG, 0.250" 4-520448-2 2
Shunt Connector 2POS 2-881545-2 5
1.2 Related Documentation From Texas Instruments
This document provides information regarding Texas Instruments' integrated circuits used in the assembly
of the INA191EVM.
Table 3. Related Documentation
Document Literature Number
INA191 product data sheet SLYS020

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2 Hardware
The INA191EVM is intended to provide basic functional evaluation of the INA191. 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 INA191EVM consists of one PCB with an option to cut out five individual PCBs, one for each
of the five gain options (A1 to A5) listed in Table 1. Each of the PCB cutouts consists of one INA191Ax
device (where x is 1, 2, 3, 4, or 5), and test points and sockets for external hardware connections, as well
as pads to solder down optional circuitry.
2.1 Features
The INA191EVM 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
• Pads for optional input protections devices (TVS or Zener diodes)
• Multiple input signal options, including a method to solder the shunt resistor (0603, 0805, 1206) and
safely measure current up to 15 A.
See the device data sheet listed in Table 3 for comprehensive information about the INA191 and the
available gain options.

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3 Operation
3.1 Quick Start Setup
Follow these procedures to set up and use one of the panels of the INA191EVM. For the following
instructions, x = 1, 2, 3, 4, or 5, depending on the selected gain option.
Step 1. Choose the desired gain option panel.
Step 2. Make sure the J3x header for the ENABLE pin is set to the appropriate voltage. For the
device to amplify the input signal, the device must be enabled by connecting the VS and
ENABLE pins together.
Step 3. Connect an external dc supply voltage (between 1.7 V and 5.5 V) to a VS test point (TP3x),
and connect the ground reference of that supply to a GND test point (TP4x, TP6x, or TP7x)
on the same panel.
Step 4. Provide a differential input voltage signal to the Rs+ and Rs– nodes by connecting the signal
leads to the J0x and J1x quick-fit tabs on the EVM. This is explained in Section 3.2. The
INA191 is a unidirectional current-sensing device because there is no reference pin;
therefore, the device can only measure current in one direction.
3.2 Measurements
The INA191EVM 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 Rs+ and Rs– pads, and these
inputs can be connected in series with the external system and load. Onboard sockets allow for a through-
hole shunt resistor to be inserted between S0x and S1x, given that the following socket pairs are shorted
with wire jumper: S4x/S5x and S1x/S2x.
To configure a measurement evaluation without a shunt resistor, follow this procedure:
1. Connect a positive differential voltage across the Rs+ (J0x) and Rs– (J1x) tabs. Given the internal
GND reference of the device, make sure that the Rs+ pin is the more positive of the two inputs.
2. Additionally, if the differential voltage supply is a floating supply, connect a –0.1-V to 40-V common-
mode voltage to the inputs by connecting the positive lead of the external voltage source to the Rs–
(J1x) 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. Measure the output voltage at the OUT test point (TP5x) with respect to GND.
To configure a measurement evaluation with a shunt resistor, follow this procedure:
1. Solder a 0603 to 1206 resistor at the R3x pads that connects the Rs+ (J0x) and Rs– (J1x) inputs.
2. Connect the Rs+ (J0x) and Rs– (J1x) 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 J0x and J1x does not exceed 15 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 OUT test point (TP5x). The output
voltage (VOUT) is equal to the gain of the device multiplied by the differential voltage measured
directly at the device input pins.

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4 EVM Components
This section summarizes the INA191EVM components. For the following components, x = 1, 2, 3, 4, or 5,
depending on the selected gain option.
4.1 R1x, R2x, R4x, R7x, R8x, C2x, C3x, C4x, C5x, C6x
R1x, R2x, R7x,R8x, and R4x are factory-installed 0-Ω0603 resistors.
C2x, C3x, C4x, C5x, and C6x are not populated except for C3x.
Collectively, these pads allow for user-defined filters for the input pins (IN+ and IN–) and output pin (OUT)
of INA191. If a filter is desired, remove these resistors and replace them with > 0-ΩSMT resistors, and
populate the capacitor pads with capacitors. Additionally, these resistors can limit current for protective
clamping diodes D4x, D3x, D2x, and D1x during overvoltage events. Additional information regarding the
use of input filtering and input protection is provided in the INA191 Low-Power, Zero-Drift, Wide Dynamic
Range, Precision Current-Sense Amplifier data sheet.
4.2 C1x
C1x is a 0.1-µF, power-supply bypass capacitor.
4.3 R3x
R3x is unpopulated, but allows a surface-mount shunt resistor to be soldered down in between the Rs+
and Rs– pads, which are sensed by IN+ and IN– input pins. If used, make sure R3x has proper power
dissipation for the user-set current load. The chosen resistor must at a minimum have a 0603 Imperial
footprint.
4.4 R5x, R6x
R5x and R6x are unpopulated resistors and are meant for 0402 shorting 0-Ωresistors that connect the
IN+ and IN- pins of INA191 directly to S2x and S5x sockets. These resistors are useful when an input filter
is implemented, and the voltages must be measured directly at the INA191 input pins.
4.5 D1x, D2x, D3x, D4x,
These diodes are unpopulated, and are meant for the onboard implementation and experimentation of
input protection circuitry when the input common-mode voltage exceeds the absolute maximum rating of
the INA191 during a transient event. D4x and D2x tie the input traces to ground, and protect for
overvoltage events. D3x and D1x connect the inputs to the supply plane, and protect for undervoltage
events.
4.6 S0x, S1x, S2x, S3x, S4x, S5x, S6x, S7x, S8x, S9x, S10x, S11x, S12x
These pin sockets are not populated, and are for inserted wires and through-hole components, or to
provide a test point. The pin sockets are used to test the INA191 with input/output filters, a through-hole
shunt resistor, test points, or a combination of any three.

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4.7 U1x (INA191)
U1x is the location for the INA191Ax test device. Five device boards are supplied with the INA191EVM
board. Each board is populated with one of the available device gains. This option allows users to test the
devices and determine the gain setting that is best for a given application.
The following list of factors are involved in selecting the appropriate device:
• The INA191 devices are identical with the exception of the different gain settings.
• 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.
4.8 J0x, J1x
J0x and J1x are 0.240-inch, noninsulated, quick-fit terminals that are designed to insert into similarly-sized
female receptacles. The kit provides two receptacles. Using insulated receptacles with J0x and J1x
terminals allows the user to make sure that there is a strong and safe connection between the current
source and EVM when dealing with high currents.
WARNING
If using the EVM to measure currents, make sure a proper power
resistor is soldered at the R3x pads. Also make sure that the
receptacles (connecting to J0x and J1x) and the respective
crimped wires can support the amperage of the current being
measured, and the necessary power dissipation. Do not exceed 15
A of current flowing between J0x and J1x. Failure to follow this
requirement can result in hot surfaces (> 55°C), damage to the
EVM, or personal injury.
Standard metal clips can electrically interface with these tabs for lower currents.
The Rs+ (J0x) and Rs– (J1x) inputs accept a differential voltage that is amplified by the selected device
gain, and is presented at the OUT test points (TP5x and S7x, if populated). 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 is determined by the supply voltage and gain of the selected
device.

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5 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 INA191EVM PCBs.
5.1 Schematics
Figure 1 through Figure 5 show the schematics for the INA191EVM PCB.

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Figure 1. INA191EVM Schematic: Gain A1 Panel

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Figure 2. INA191EVM Schematic: Gain A2 Panel