Texas Instruments INA282-286EVM User manual

User's Guide
SBOU083–September 2010
INA282-INA286EVM
This user’s guide describes the characteristics, operation, and use of the INA282-286EVM evaluation
module (EVM). This EVM is designed to evaluate the performance of the INA282-286 family of voltage
output current shunt monitors. This EVM has a flexible configuration, allowing for user evaluation suitable
to a variety of applications. This document also includes a schematic and a complete bill of materials.
Contents
1 Introduction and Overview ................................................................................................. 2
2 Quick Start Setup and Use ................................................................................................ 4
3 INA282-286EVM Circuit .................................................................................................... 6
4 Reference Voltage Setup ................................................................................................. 10
5 INA282-286EVM Schematic ............................................................................................. 13
6 Bill of Materials ............................................................................................................. 14
List of Figures
1 Hardware Included with the INA282-286EVM........................................................................... 3
2 Measurement with Shunt .................................................................................................. 4
3 Measurement without Shunt............................................................................................... 5
4 TO-247 Package in R1..................................................................................................... 6
5 CS3 Package in R1......................................................................................................... 6
6 TO-126 Package in R1..................................................................................................... 6
7 TO-220 Package in R1..................................................................................................... 6
8 Radial Package in R2 ...................................................................................................... 8
9 U1 Populated With DIP Board............................................................................................. 9
10 Unidirectional Mode: Positive Differential Voltage Configuration.................................................... 10
11 Unidirectional Mode: Negative Differential Voltage Configuration .................................................. 11
12 Bi-directional Mode: One Reference to Ground, One Reference to Supply Configuration ...................... 11
13 Bi-directional Mode: Specific Voltage Required Configuration ...................................................... 12
14 Bi-directional Mode: Buffered Voltage Configuration ................................................................. 12
15 INA282-286EVM Schematic ............................................................................................. 13
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Introduction and Overview www.ti.com
1 Introduction and Overview
1.1 INA282-286
The INA282-286 devices are voltage output, high-side measurement, bi-directional, zero-drift current shunt
monitors. This family of devices has gains that range from 50V/V to 1000V/V. 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 INA282-286 devices can sense voltage drops across shunts at common-mode
voltages between –14V to 80V, independent of supply voltages. These devices operate with supply
voltages between 2.7V and 18V and draw a maximum of 900µA. The low offset of the zero-drift
architecture enables current sensing with maximum drops across the shunt as low as 10mV full-scale.
The INA282-286 devices are currently available in an SOIC-8 surface-mount package. Table 1
summarizes the available device options.
Table 1. INA282-286 Device Summary
Product Gain
INA282 50
INA283 200
INA284 500
INA285 1000
INA286 100
1.2 INA282-286EVM
The INA282-286EVM 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 layout of the INA282-286EVM printed circuit board (PCB) is designed to provide these features:
• Easy handling of the small package; a mechanical drawing of the recommended land pattern is found
at the end of the product data sheet.
• Easy access to all pins of the device
• Space for optional input filtering capacitors and resistors as well as a prototype area for additional
user-defined circuitry
• Space for shunt resistors of various footprints
• Multiple input signal options
• Evaluation of all gain options through provided device boards as well as a location to solder a test
device directly on to the board
The INA282-286EVM allows the user to install a shunt resistor, and then connect both the common-mode
voltage and load to develop the input voltage, or to omit the shunt resistor and apply a differential voltage
directly to the device input. This flexibility allows a user to test the device operation in a simulated manner
as well as in an actual application.
Refer to the INA282-286 product data sheet for comprehensive information about the INA282-286 family
of devices.
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www.ti.com Introduction and Overview
1.3 Hardware Included
The INA282-286EVM features the SOIC-packaged version of the INA28x. Device boards populated with
each of the available gain versions of the INA282 family of devices will be provided in all INA282-286EVM
delivered, as Figure 1 shows.
Figure 1. Hardware Included with the INA282-286EVM
The INA282-286EVM kit is shipped with the following items:
• INA282-286EVM PCB
• Five populated test boards (INA282, INA283, INA284, INA285, INA286)
If any of the items in the EVM kit shipment are missing or damaged, please contact the Texas Instruments
Product Information Center nearest you to inquire about a replacement.
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+
C1
R4
R3
R1/2 IS
Load
Load
INA282
INA282-286EVM
V+
V+
VOUT
REF1
REF2
VIN
2.7V to 18V
GND
Quick Start Setup and Use www.ti.com
2 Quick Start Setup and Use
Follow these procedures to set up and use the INA282-286EVM.
Step 1. Insert the device board to be evaluated into the U1 location. The U1 location allows the user
to either evaluate one of the provided device boards or to install the test device directly on
the surface-mount pads in the U1 footprint.
Step 2. Connect an external dc supply voltage between 2.7V and 18V to the V+ terminal referenced
to the GND terminal of T4. The INA282-286 device output voltage is limited to 40mV above
ground to 400mV below the supply level.
Step 3. The default connection for the references is to have the jumper in place on J3 and J4. This
configuration allows for bi-directional operation with the output referenced to mid-supply. The
voltage applied at the reference input can be varied depending on how the device is to be
used. Further details regarding the use of the reference voltage are discussed later in this
guide; refer to Section 4 for additional information on configuring the reference pins based on
the user's application requirements.
Step 4. Connect the Input.
2.1 Measurement With Shunt
This connection method allows the user to install a shunt resistor on the evaluation board and connect the
common-mode voltage and load to incorporate the test device directly into a sample application, as
Figure 2 illustrates. To configure a measurement evaluation with a shunt, follow these procedures.
1. Install shunt resistor into the R2 location. If not using a surface-mount or through-hole shunt, refer to
Section 3.1 for a summary of the R1 component specifications.
2. Connect the common-mode voltage to the VIN terminal of T1.
3. Connect load to the Load terminal of T1.
Figure 2. Measurement with Shunt
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+
+
C1
R4
R3
R1/2 IS
Load
INA282
INA282-286EVM
V+
V+
VOUT
REF1
REF2
VIN
VDIFF
VCM
2.7V to 18V
GND
www.ti.com Quick Start Setup and Use
2.2 Measurement Without Shunt
This connection method allows the user to either simulate the voltage developed across a sense resistor
based on a given set of system conditions, or to connect the INA282-286EVM remotely to an existing
shunt already included in an example application. Figure 3 illustrates a measurement configuration without
a shunt. As a result of the internal architecture of the INA282 family of devices, if this measurement
method is used, make sure the voltage source is either a very low impedance or the differential voltage
applied to the inputs is buffered to prevent additional errors in the circuit.
To configure a measurement evaluation without a shunt, follow these procedures.
1. Connect a differential voltage to the VIN+ and VIN– terminals of T2.
2. Measure the output voltage at the VOUT terminal of T2.
Figure 3. Measurement without Shunt
NOTE: The output voltage is equal to the reference voltage plus the gain of the device multiplied by
the differential voltage measured directly at the device input pins.
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INA282-286EVM Circuit www.ti.com
3 INA282-286EVM Circuit
This section summarizes the INA282-286EVM components.
3.1 R1
R1 can be used for shunt resistors that have a package that is not easily adaptable to a standard,
two-terminal, through-hole footprint or to a 0603 through 1206 surface-mount footprint. Specifically, this
component location was added to allow for the use of TO-126, TO-220, TO-247, and four-terminal inline
radial packages such as the CS3 series of shunts from Ohmite. The numbers located on the PCB
between R1 and J1 correspond to each of the holes in the R1 footprint. Holes with the same number are
connected together. The designation of 1and 2indicates that particular hole is connected directly to the
VIN+ and VIN– inputs, respectively. The designation of 3and 4indicates that particular hole is intended for
the sense measurement of a four-wire shunt.
Care must be taken to ensure that the shunt is placed in the correct position in the R1 location. This
placement consideration is evident when using a two-connection shunt with a spacing of 200 mils (.200in
or 5,080mm). As shown in Figure 4 through Figure 7, the shunt must be placed in the second
1-designated hole in order for the other leg to fit into the 2position. If the shunt is placed in the first 1
position, the second leg is left floating; no differential voltage is then generated for the current monitor.
Additional packages can be tested by using the provided prototype area of the board.
Figure 4. TO-247 Package in R1 Figure 5. CS3 Package in R1
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Figure 6. TO-126 Package in R1 Figure 7. TO-220 Package in R1
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INA282-286EVM Circuit www.ti.com
3.2 R2
R2 is intended to handle two- and four-terminal radial packages (as Figure 8 illustrates) as well as
surface-mount packages that range in size from 0603 to 1206.
Figure 8. Radial Package in R2
3.3 R3, R4, C1
R3 and R4 are factory-installed 0Ωresistors. These resistors, in combination with C1, form an input filter.
These locations allow for through-hole and surface-mount packages that range in size from 0603 to 1206.
Additional information regarding the use of input filtering is provided in the INA282-286 product data sheet.
3.4 Bypass Capacitors and Jumpers
C2, C3, and C4 are 0.1mF supply bypass capacitors.
J1 is intended to be used as measurements points of R1, if necessary.
J2 is used as a test port at the factory but can be used for the corresponding input and output pins, if
desired.
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3.5 U1
U1 is the location for the test device. Five device boards are supplied with this INA282-286EVM board;
each device board is populated with one of the available device gains. This interchangeable option allow
users to test the devices and determine the gain setting that is best suited for a given application.
Here is a list of the factors involved in selecting the appropriate device.
• The INA282-286 devices are identical with the exception of different gain settings.
• The limiting factor that requires attention to be given to device selection is the output voltage.
• The output voltage has a restriction: it must remain within the range of 40mV above ground to 400mV
below the supply voltage.
• The differential input voltage is either applied across the inputs, or developed based on the load
current flowing through the shunt resistor.
• 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.
• 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
smaller gain.
In addition to being able to accommodate the device boards, a surface-mount footprint has been added as
well. This footprint, though, is for an MSOP package that will be available at a later date. This option will
allow a device to be installed directly onto the EVM if needed. Figure 9 shows the U1 slot populated with a
DIP board device as an example.
Figure 9. U1 Populated With DIP Board
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REF1
REF2
Reference Voltage Setup www.ti.com
3.6 Voltage Inputs
The VIN+ and VIN– terminals of T2 are intended to be used if the designer is configuring this EVM for
measurement without an onboard shunt resistor (see Figure 3). These inputs accept a differential voltage
that is amplified by the selected device gain and is presented at the VOUT terminal of T2. These inputs
could 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,
reference voltage, and gain of the selected device.
The VIN and Load terminals of T1 are intended to be used if the user configures this EVM for
measurement with a shunt resistor, as shown in Figure 2. The common-mode voltage should be
connected to the VIN terminal and the load should be connected to the Load terminal. The shunt can be
installed in R1, R2, or the prototype area, and wired to the R2 footprint. As in the setup for the
measurement without a shunt resistor, the input voltage range and polarity are determined by the supply
voltage and the reference voltage, and the gain of the selected device.
3.7 Miscellaneous
The REF1 and REF2 terminals of T3 allow the user to configure the INA282-286EVM for either
unidirectional or bi-directional operation.
Two easily-accessed oscilloscope ground pads are located on the PCB to facilitate easier probing.
4 Reference Voltage Setup
The INA282-286 devices allow an external voltage signal to be used for the device’s reference voltage.
This reference voltage determines how the output responds to certain input conditions. The configurable
settings of the reference allow these devices to be used in both unidirectional and bi-directional
applications.
4.1 Unidirectional Mode
Unidirectional refers to a load current that flows in only one direction. For unidirectional applications, the
reference voltage can be set to ground or to +5V. If the reference is set to ground, the output is set at near
ground with no input voltage, and responds to input voltages that are positive with respect to VIN–/Load. If
the reference is set to +5V, the output is set near +5V with no input voltage and responds to input
voltages that are negative with respect to VIN–/Load.
In unidirectional applications that are configured to create a positive differential voltage across the device
input pins with respect to the VIN– pin, both the reference pins can be tied to ground, as shown in
Figure 10. This configuration results in an output set near to ground with no input voltage. Increasing the
differential input voltage increases the output up from the near ground output level.
Figure 10. Unidirectional Mode: Positive Differential Voltage Configuration
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