• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 388 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

INA186: VSENSE Minimum voltage

Asha C
Intellectual 445 points

Part Number: INA186

Hello,

We are using 20mhom sense resistor , for 0.5A current we get sense voltage of 10mV. 

But i see gain error mentioned wrt Vout >0.1V , is 1%. I do not see wrt sense voltage.

Could you please provide feedback on this!

  • 0
    TI__Mastermind 19245 points

    Hello,

    Thank you for your post. 

    This is a great question. The reason we show it with respect to the output is that there are many errors that contribute to the gain error. 

    This error presents itself as a different slope on the ideal transfer curve. Below is the equation for the relationship between Vsense and Vout for current sense amplifiers. 

    There are the gain error contributions that you would use from the EC table for the above equation:

    We also have this video explaining the process: https://www.ti.com/video/6117678391001

    I hope this helps, 

    Joe

  • 0
    Intellectual 445 points

    Hello Joe,

    Thanks for the reply!

    I have another query with the same part.

    WRT Vref pin , we are going with Vref of 0.5V which is derived from a resistor divider of source 3.3V using 0.1% tolerance resistors.

    Could you please confirm if this approach will effect the gain or any other performance of the current sense amplifier.

    Attached below is the circuitry for reference!

  • 0 in reply to Asha C
    TI__Mastermind 19245 points

    Hello Asha,

    Thank you for the follow-up. This is another great question. I like the bypass you are using for the reference to add more stability.

    I would consider the accuracy of this reference to make sure this is meeting your needs. There is an app note on driving reference pins and here is an image from the following app note: https://www.ti.com.cn/cn/lit/an/sboa551/sboa551.pdf 

    The highest accuracy is using a reference IC, medium accuracy is Divider + Buffer, and lowest accuracy is a divider approach like the one you are implementing. The bypass cap does help stabilize your divider but not to the accuracy that a reference IC would offer. 

    To reiterate, you should see if the performance of your circuit meets your needs and if this divider does, great. If not, here are some other options. 

    I hope this helps. 

    Best Regards, 

    Joe