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INA195/196

eli
Guru 13485 points
Other Parts Discussed in Thread: INA195

Can you please clarify the issue of using the INA195/196 to measure current of -15V supply , even though the maximum absolute rating of the device is -16V (stress issues).

If not how can I decrease the input current (As mentioned in the absolute maximum rating )  without affecting the accuracy ?

  • 0
    TI__Mastermind 25805 points

    Hello Eli,

    This is the first I have heard of any issues measuring current at a common-mode voltage of -15V with the INA195/6.  If possible, please share your schematic and data.

  • 0 in reply to Pete%20Semig
    Guru 13485 points

    Hi,

    As needed to measur -15V which is close to the maximum absolute rating of the device ,customer is hesitate to use it.

    Can you confirm it can be usaed with no problems at all?

  • 0 in reply to eli
    TI__Mastermind 25805 points

    Hello Eli,

    The device will meet the specifications (under the given conditions) outlined in the Electrical Characteristics table.  I can't confirm, however, that it will work for the customer for I have no knowledge of their system.

  • 0 in reply to Pete%20Semig
    Guru 13485 points

    Hi,.

    See attached schematic+questions

    .5732.INA195196.msg

  • 0 in reply to eli
    TI__Mastermind 25805 points

    Hello Eli,

    Thanks for the schematic.  Unfortunately it is difficult to read.

    There are 5kohm (+/-30%) resistors in series with the inputs of the device.  What is the customer's load impedance?  We typically see loads of much lower impedance.

  • 0 in reply to Pete%20Semig
    Guru 13485 points

    Hi Pete,

    As I understand, in case of voltage that is greater from -16V I need to limit the input current to 5mA. This is the reason that I thought that serial resistors that I will connect to the inputs will solve this issue and protect the inputs.

    Now I think serial resistors is not solution since the 5Kom inside resistor is used for converting the voltage to current and any serial resistor will change the gain.

    If it correct,Do you have another solution for voltages greater from -16V (with the same device or maybe other device ) ?

  • 0 in reply to eli
    TI__Mastermind 25805 points

    Hello Eli,

    I don’t recommend using the device with a common-mode outside of the specified range.  If the device is normally monitoring a common-mode voltage of -15V and may occasionally experience a transient event, you may be interested in reading the Transient Protection section of the datasheet.  It recommends the use of zeners or transorbs to protect the inputs. That is probably your best option if my assumption is correct.