Texas Instruments INA234EVM User manual

User’s Guide
INA234EVM and INA236EVM
ABSTRACT
This user’s guide describes the characteristics, operation, and use of the INA234 and INA236 evaluation
modules (EVMs). These EVMs are designed to evaluate the performance of the INA234 and INA236.
Throughout this document, the terms evaluation board, evaluation module, and EVM are synonymous with
the INA234EVM and INA236EVM. This document includes a schematic, reference printed circuit board (PCB)
layouts, and a complete bill of materials (BOM).
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Table of Contents
1 Trademarks..............................................................................................................................................................................2
2 Overview..................................................................................................................................................................................3
2.1 Kit Contents........................................................................................................................................................................3
2.2 Related Documentation From Texas Instruments.............................................................................................................. 4
3 Hardware................................................................................................................................................................................. 4
3.1 Features............................................................................................................................................................................. 4
4 Operation.................................................................................................................................................................................5
4.1 Quick Start Setup............................................................................................................................................................... 5
4.2 EVM Operation...................................................................................................................................................................5
5 Circuitry................................................................................................................................................................................. 15
5.1 Current Sensing IC...........................................................................................................................................................15
5.2 Input Signal Path..............................................................................................................................................................15
5.3 Digital Circuitry................................................................................................................................................................. 15
6 Schematics, PCB Layout, and Bill of Materials................................................................................................................. 16
6.1 Schematics.......................................................................................................................................................................16
6.2 PCB Layout...................................................................................................................................................................... 18
6.3 Bill of Materials.................................................................................................................................................................19
7 Revision History................................................................................................................................................................... 20
1 Trademarks
All trademarks are the property of their respective owners.
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2 Overview
The INA234 and INA236 devices are digital power monitors with integrated 16-bit (INA236) and 12-bit (INA234)
delta-sigma ADCs specifically designed for current-sensing applications. The devices can measure a selectable
full-scale differential input of ±81.92 mV or ±20.48 mV across the shunt with common-mode voltage support
from –0.3 V to +42 V (–0.3 V to +28 V for INA234). The built-in digital accumulation calculates average power
and current if calibration register is programmed. The INA234 and INA236 devices also have built-in diagnostics
to indicate system health accessible through a digital output pin, ALERT. The output can be interfaced with a
multitude of microcontrollers (MCUs) with a standard I2C interface.
Table 2-1. Device Summary
PRODUCT
DIGITAL
PROTOCOL
ADC
RESOLUTION
MAX GAIN
ERROR
MAX OFFSET
VOLTAGE
INA234 I2C 16-bit 1% ±100 µV
INA236 I2C 12-bit 0.2% ±10 µV
2.1 Kit Contents
Table 2-2 lists the contents of the EVM kit. Contact the nearest Texas Instruments Product Information Center if
any component is missing.
Table 2-2. Kit Contents
ITEM QUANTITY
INA234EVM OR INA236EVM board 1
Note that this EVM requires the TI Sensor Control Board (SCB), which is sold separately.
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2.2 Related Documentation From Texas Instruments
This user's guide is available from the TI website under literature number SBOU241. 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 (800)
477-8924 or the Product Information Center at [phone]. When ordering, identify the document by both
title and literature number. Table 2-3 lists documentation related to the EVM. Click the links in Table 2-3 for
further information. The device name links to the product web folder on www.ti.com. The literature number links
to the document PDF.
Table 2-3. Related Documentation
DOCUMENT TITLE
DOCUMENT LITERATURE
NUMBER
INA234 data sheet SBOS844
INA236 data sheet SBOSA81
3 Hardware
The EVM is an easy-to-use platform for evaluating the main features and performance of the INA234 or INA236.
The EVM supports current measurements up to 10 amps, and includes a graphical user interface (GUI) used to
read and write device registers as well as view and save results data.
The EVM is intended to provide basic functional evaluation of the devices. The layout is not intended to be a
model for the target circuit, nor is it laid out for electromagnetic compatibility (EMC) testing. The EVM consists
of two printed circuit boards (PCBs). The larger PCB is referred to as the EVM, and has either the INA234 or
INA236 installed. The smaller PCB is referred to as the SCB Controller, and is used to interface the EVM with
the GUI.
3.1 Features
• GUI support to read and write device registers as well as view and save results data
• EVM detached from SCB for custom use cases
• Conveniently powered from a common micro-USB connector through the SCB
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4 Operation
4.1 Quick Start Setup
The following instructions describe how to set up and use the EVM.
1. Purchase an SCB if you do not already have one.
2. Download this driver and install it as an administrator: https://www.ti.com/lit/zip/sbac253.
3. Attach the EVM to the SCB Controller as shown in Figure 4-1.
a. Refer to Figure 4-2 when connecting multiple EVMs of the same type together.
4. Connect the EVM to a PC using the provided USB cable.
a. Insert the micro USB cable into the SCB Controller onboard USB receptacle J2.
b. Plug the other end of the USB cable into a PC.
5. Access the GUI from this link in either Chrome or Firefox: https://dev.ti.com/gallery/info/3907820/
INA234_236EVM_GUI/ver/1.0.0/.
6. Connect the GND reference of the external system to the GND node of the EVM (pin 1 of J1).
7. Provide a differential input voltage signal to the IN+ and IN– nodes by connecting the signal leads to J1 pin 5
or 6 and J1 pin 3 or 4 on the EVM as explained in Section 4.2.2.
4.2 EVM Operation
To use the EVM with the SCB Controller (sold separately), connect the EVM as shown in Figure 4-1.
Figure 4-1. EVM Connected to SCB Controller
If using multiple EVMs, connect them as shown in Figure 4-2. Make sure to use a different chip address for each
device. The GUI only supports one EVM/device type at a time.
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Figure 4-2. Multiple EVMs Connected to SCB Controller
4.2.1 Setup
4.2.1.1 Driver Installation
Download and install this driver: https://www.ti.com/lit/zip/sbac253. This is a one-time step per computer. Unzip
the folder and run the .exe file with administrator privileges.
4.2.1.2 Firmware
Firmware updates will be pushed through the GUI (requires previous driver to be installed). Downloaded offline
GUIs will only update the SCB Controller with the latest firmware available at the time of download. To check for
the latest GUI or Firmware updates, launch the GUI from the web browser.
4.2.1.2.1 Firmware Debug
If the firmware must be manually reinstalled for any reason, follow these steps to reinstall the firmware. Make
sure the EVM is connected to the SCB.
1. First, see if the GUI can program the firmware manually.
a. Plug in the SCB controller to the PC.
b. Launch the GUI.
c. It is possible that the MCU has already entered DFU mode. If so, the GUI may notify you and try to
update the firmware to the latest version.
d. If it does not update automatically, go to File > Program Device...
2. If that does not work (or if the Program Device button is grayed out), manually configure the MCU on the
SCB Controller to be in Device Firmware Update (DFU) Mode. This can be done through either of the below
methods with the SCB Controller powered on:
a. Through software:
• For safety, turn off and disconnect all load sources and external voltages.
• Send the command 'bsl' on the SCB's USB Serial (COM) port.
b. Though hardware:
• While shorting the two test points labeled "DFU" (shown in Figure 4-3) with a pair of tweezers (or
wire), press and release the RESET button.
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Figure 4-3. Test Points Used to Enter DFU Mode Manually
With the MCU in DFU mode, the firmware can now be uploaded through the method outlined in Step 1.
4.2.1.3 GUI Setup and Usage
The GUI can be accessed from this link in either Chrome or Firefox: https://dev.ti.com/gallery/info/3907820/
INA234_236EVM_GUI/ver/1.0.0/.
4.2.1.3.1 Initial Setup
To set up the GUI the first time:
1. Make sure that the previously mentioned driver was installed successfully to ensure that everything works
properly and that the GUI can update the EVM firmware, if necessary.
2. Check to make sure the EVM/SCB Controller unit is plugged into the PC, then go to the previously-provided
GUI link.
3. Click the GUI Composer application (Figure 4-4) to launch the GUI from the web browser.
Figure 4-4. GUI Composer Application
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a. Follow the prompts to download the TI Cloud Agent and browser extension shown in Figure 4-5 for the
first-time GUI Composer setup These prompts will appear after you close the README.md dialog.
Figure 4-5. TI Cloud Agent
4. Optionally, click the icon in the GUI Composer application (Figure 4-4) and follow the prompts to
download the GUI for offline use.
4.2.1.3.2 GUI Operation
To operate the GUI, follow these steps:
1. Connect to and launch the GUI as described in Section 4.2.1.3.1.
2. Check to make sure that the EVM connected to the GUI, then close the README.md file page to initiate the
connection. If successful, the Hardware Connected message should be visible near the bottom-left corner
of the GUI as in Figure 4-6.
Figure 4-6. Hardware Connected
a. A green indicator with the device type and the text DEVICE CONNECTED should also be visible near
the top-left of the GUI window, as shown in Figure 4-7.
Figure 4-7. Device Connected
b. If Hardware Connected and DEVICE CONNECTED do not show in the GUI, check the different
hardware COM ports under Options >> Serial Port, as shown in Figure 4-8.
Figure 4-8. Change Serial Port
c. If the hardware still does not connect, make sure you are using the correct GUI/EVM combination.
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i. If you are using the correct GUI/EVM combination, you may need to reprogram the firmware of the
SCB, as described in Firmware Debug.
3. Click the (registers) icon on the left menu to view and edit the device register map.
a. From this page, you can read and write register settings on the EVM. For questions about a register or
register bit field, select the icon. For more questions about registers, check the data sheet.
4. Click the (plots) icon on the left menu to go to the plots page. Under the plots page, you can view and
collect results data over time. The plots page will look similar the one shown in Figure 4-9, depending on the
connected device.
Figure 4-9. GUI Plots Page
a. Below is a description of how to use the buttons and settings at the top of the plots page and next to
each plot:
i. Check the Results to collect/show box on the left to collect data from specific register values. If
a results register is unselected, then the plot below will not show the data and the EVM will not
try to read this value during the collect cycle. If you disable one of these settings while the EVM is
collecting data, then the plot will not show, but data will still be collected and the plot will update in
the background.
ii. Set the Number of EVMs drop-down menu to the number of EVMs currently in use. See Figure
4-2 to see how to attach multiple EVMs together. Use the onboard switch(es) to select a different
address for each EVM. The GUI only supports one EVM/device type at a time.
1. Set the switch settings for each connected EVM. EVM 1 will automatically populate with the
lowest addressed device unless a setting has already been selected.
2. Click the LINK TO REGMAP button to set the regmap of the desired EVM. Use this button to
change settings for each connected device through the register map. Functionally, this button
sets the default read/write address in the MCU and then reads all register values back to update
the register map. Note that if data is being collected at a high frequency, then this may cause a
minor delay in the collection data. For optimal performance, set device settings before you start
collecting data.
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iii. Click the COLLECT DATA button to start data collection.
1. In this mode, the MCU reads and sends the selected result values for each device over a USB
BULK channel. All results from one device are read before moving on to the next device. All
result values from all EVMs together are considered one "sample set".
2. The Delay between samples shows the delay between the start of each sample set. A delay
of 0 corresponds to "as fast as possible". If the delay used is shorter than the amount of time it
takes to read all results from all EVMs, the setting would be the same as a delay of 0. Note, the
registers are read when the firmware is ready to read them, optionally based on the delay timer.
It does not take into account conversion time or averaging. Although you can read and write to
other registers through the register map page while collecting data, it is possible that this adds a
delay to the data being collected.
3. Click the CLEAR ALL PLOTS button to clear the data from all plots together. This can be done
individually for each plot. Similarly, you can check the #Samples all: box to change the number
of samples shown in each plot. This can also be done individually per plot.
4. Click the SAVE PLOT button next to each plot to save the data in a spreadsheet.
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