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SBOU196 – December 2017
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Copyright © 2017, Texas Instruments Incorporated
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.
