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INA310EVM: Creating a load current measurement module.

Tomoki Minamino
Prodigy 10 points

Part Number: INA310EVM
Other Parts Discussed in Thread: CS-AMPLIFIER-ERROR-TOOL, INA293

Tool/software:

Thank you for your help.
I'm a new engineer and would appreciate any advice.
I am thinking of creating a high-side current detection module using the INA310EVM.
The load current I want to measure is minimum 1mA, maximum 1A, with a bandwidth up to 1MHz.
I plan to observe the waveform of the INA310EVM output using an oscilloscope, and perform FFT and AC analysis.
I understand that if INA310A2 is used, the measurable bandwidth specifications are met, but is this correct?
I would also appreciate any advice you could give me on things to keep in mind when selecting a shunt resistor.
I would be grateful for any guidance you can provide.

  • 0
    TI__Mastermind 30535 points

    Hello Minamino-san,

    Thank you for using the TI forum. The INA310A2 has a bandwidth of 1.3MHz, so this will be sufficient for your 1MHz requirement. You may be interested in our TI Precision Labs video training series, which can be found here: https://www.ti.com/video/series/precision-labs/ti-precision-labs-current-sense-amplifiers.html. This video series has many helpful topics that can get you started with using current sense amplifiers, including a video on how to choose a shunt resistor (under the "Current sense amplifier applications" subsection). For selecting shunt resistors in general, you will have the most accuracy when picking the largest shunt you can for the application, but that will use more power so there is a balance based on your needs. You may also be interested in some other recourses we have for this device (including the CS-AMPLIFIER-ERROR-TOOL), which can be found here: https://www.ti.com/product/INA310A#design-development.  

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 10 points

    Thank you for your reply. I apologize for the late reply. I am starting to design a circuit using the INA310A2. The power supply voltage is 12V. The shunt resistor value is 100mΩ. I am considering a configuration of the above. For the circuit around CMPin and CMPout, I refer to table 8-2 on page 23 of the datasheet. The measurement range is 100uA to 1A, and the frequency band is required to be up to 1MHz. IMAX * RSENSE *GAIN=1A*200m*50=10V＜Vs IMIN * RSENSE *GAIN=100uA*200m*50=10mV＞VSN I believe that the conditions are met from the above formula, but if there are any mistakes, please advise me.

  • 0 in reply to Tomoki Minamino
    TI__Mastermind 30535 points

    Hello Minamino-san,

    The values you gave in your formula look correct, however I will note that you used a shunt of 200mΩ in your equations but said 100mΩ in the sentence above. I will presume you meant 200mΩ like your equations. 

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 10 points

    Thank you for your reply. As you pointed out, I plan to use 200mΩ. I apologize for the incorrect statement. I also have a new question. I was researching current sense amplifiers and found the INA293. I think that unlike the INA310, it can have a simpler circuit configuration. By using a shunt resistor of 200mΩ, as with the INA310, I think it will be possible to measure 100uA to 1A, with a frequency band up to 1MHz. I would appreciate your advice if my understanding here is incorrect. I apologize for asking the same question so many times, and I would appreciate your help.

  • 0 in reply to Tomoki Minamino
    TI__Mastermind 30535 points

    Hello Minamino-san,

    Yes, if you do not need the comparator function of the INA310, then the INA293 looks like it would work fine for you. Note that both the INA310 and INA293 have input bias currents around 20µA. This will add some error, especially at lower current measurements. You can calibrate your system to mitigate this error. Other devices that have a lower input bias current would not meet your bandwidth requirements. 

    Regards,

    Mitch