• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 2 answers
  • Subscribers 47 subscribers
  • Views 480 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.

INA381-Q1: Multi-Device in Parallel

Evan Wang
Genius 9690 points
Part Number: INA381-Q1
Other Parts Discussed in Thread: INA381

Hi Team,

May I know whether I can leverage all three INA381-Q1 and connect them to the same Rsense?

We will connect the VOUT pin to CMPIN pin in each INA381-Q1 and set the different threshold(CMPREF) for each CMPREF pin to get different trigger(/ALERT) condition.

All the /ALERT pins will connect to MCU's GPIO0/1/2.

But since the source is the same so I would like to know whether there is any side effect for such connection.

Like parasitic capacitance or offset current.

Our targeting current through that Rsense is 20mA ~ 100mA.

Kindly let us know if you have any concerns. 

  • 0
    TI__Expert 8175 points

    Hello,

    The biggest effect you will see is that the additional input current to the INA381 devices will create an additional voltage drop across the resistor, and this will cause the measurement to change slightly. For the INA381, the input bias current is typically 80µA, so you should expect an additional error current of about 0.24mA, or 1.2% of the 20mA current you are trying to measure. This will be the main effect, I believe the parts will function as you expect otherwise.

    I am curious; what are you accomplishing by using these devices together? Keep in mind that the main error specifications for these devices will be similar.

    Let me know if you have any more questions,

    Levi DeVries

  • 0 in reply to Levi DV
    TI__Genius 9690 points

    Hi Levi,

    Thank you for the comment.

    I will send you the block diagram through email.

    close this case first.

  • 0 in reply to Evan Wang
    TI__Genius 9690 points

    Hi Levi ,

    One more question.

    May I know the definition of the VIH & VIL of comparator part?

    Means if we use VOUT as COMPIN then we have to make sure VOUT/COMPIN pin is larger than 1.4V than internal comparator can work?

    Thank you. 

  • 0 in reply to Evan Wang
    TI__Genius 9690 points

    Hi Levi,

    May I have your comment?

    Thank you.

  • 0 in reply to Evan Wang
    TI__Expert 8175 points

    Hello Evan,

    Sorry for the late response I was travelling and was unable to respond.

    The VIL and VIH specs refer to the digital input pin of the comparator, the only digital pin being the RESET pin which is used to switch the device in and out of latched mode.

    Let me know if you have any more questions,

    Levi DeVries

  • 0 in reply to Levi DV
    TI__Genius 9690 points

    Hi Levi,

    oh~ i see.

    Thank you for your help.