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INA240: Current sense amplifier recommendations

DanFer
Prodigy 60 points
Part Number: INA240
Other Parts Discussed in Thread: INA190, INA191, , INA301

Hi there,

I am looking for the most accurate current sense solutions for two situations:

1) 2 mOhm shunt where the voltage drop across can range from 7 mV to 25 mV

- CM Voltage range support from 2.8 to 4 V

- Bandwidth of at least 25 KHz

- A gain of at least 50 (the greater the better)

- Minimal gain error, offset voltage

Possible options I have found: INA190, INA191, INA240

2) 10 mOhm shunt where the voltage drop across can range from 11 mV to 24 mV

- CM Voltage range support from 5 to 14 V

- Bandwidth of at least 50 KHz

- A gain of at least 50 (the greater the better)

- Minimal gain error, offset voltage

Possible options I have found: INA240, INA301
Please let me know
  • 0
    TI__Mastermind 27715 points

    Hello DanFer,

    1. INA190 or INA191 is the highest-performance choice in terms of offset voltage and gain error here. For the A2 version (gain of 50 V/V) the bandwidth is typically 37 kHz. At maximum gain of 500 V/V with the A5 version, bandwidth is 27 kHz.
    2. INA240 is the best choice here due to the higher bandwidth requirement. The INA301 also works, but offset voltage is significantly higher, and you don't mention needing the comparator function for overcurrent detection.

    Best regards,

    Ian Williams
    Applications Manager
    Current Sensing

  • 0 in reply to Ian Williams
    Prodigy 60 points

    Thanks for the feedback. What is the difference between the INA190 and INA191?

    Are there any other options which are better fits but not mentioned by me?

  • 0 in reply to DanFer
    TI__Mastermind 27715 points

    Hi Dan,

    The INA191 is the INA190 in a small wafer chipscale package (WCSP). The die is the same.

    In terms of best offset voltage and gain error while meeting the required Vcm and bandwidth, these are the best fits.

    Best regards,

    Ian Williams

  • 0 in reply to Ian Williams
    Prodigy 60 points

    Thanks Ian. It looks like the INA190 and 191 have different accuracies. It looks like the 191 is more accurate with a lower offset voltage?

    How can they be the same die? Is the difference in packaging causing these differences?

  • 0 in reply to DanFer
    TI__Mastermind 27715 points

    They are indeed the same die, but yes the package-level effects and the results of our characterization and test affect how we spec the datasheet. In truth the performance is extremely similar from one to the other - I doubt you would see much difference in the end application. Either way, they're both among the most precise current sense amplifiers in the industry, and offered for the same 1ku price.

    Best regards,

    Ian Williams

  • 0 in reply to Ian Williams
    Prodigy 60 points

    Great, thanks for all of your help!

  • 0 in reply to DanFer
    Prodigy 60 points

    Regarding the different gain options, I see that for the INA190, increasing the gain results in an increase in gain error whereas the INA191 shows the reverse relationship. Is this an error?

  • 0 in reply to Ian Williams
    TI__Mastermind 27715 points

    Just to back up what I'm saying with a quick calculation:

    The minimum sense voltage in your first application is 7mV. The %error due to offset voltage is dominant at minimum input and is computed as simply (Vos/Vsense)*100.

    Using typical offset:

    • INA190: %error = (-3uV / 7mV) * 100 = -0.043%
    • INA191: %error = (-2.5uV / 7mV) * 100 = -0.036%

    Using maximum offset:

    • INA190: %error = (15uV / 7mV) * 100 = 0.21%
    • INA191: %error = (12uV / 7mV) * 100 = 0.17%

    Best regards,

    Ian Williams

  • 0 in reply to DanFer
    TI__Mastermind 27715 points

    DanFer, I will double-check the gain error vs. gain relationship for both parts and get back to you early next week.

    Best regards,

    Ian Williams

  • 0 in reply to Ian Williams
    TI__Mastermind 27715 points

    DanFer, I have confirmed with our test team that the datasheets are correct. They reflect some minor changes in our test system that were made for INA191, which came after INA190.

    Best regards,

    Ian Williams

  • 0 in reply to Ian Williams
    Prodigy 60 points

    Great, so increasing the gain for the INA191 decreases the gain error?

  • 0 in reply to DanFer
    TI__Mastermind 27715 points

    That's right, or put another way, the A1 version at 25 V/V has just slightly worse gain error than the higher gain versions.

    Best regards,

    Ian Williams