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INA149: -IN and +IN OPEN → Vout=?

cafain
Mastermind 6445 points
Part Number: INA149

Hi, Staff

We are evaluating INA149.

Please confirm below.
The circuit configuration of INA149 data sheet (SBOS579B) page13 Figi43 is evaluated.

What kind of voltage does Vout output when both the -IN and +IN input terminals are open?

As a result of evaluation, Vout is confirmed to be +13.5V or -13.5V.

best regards

cafain

  • 0
    TI__Mastermind 20097 points

    Cafain,

    1. I would expect the output to go to 0V if you are configured as shown in figure 43, and the in+ and in- bin are floating, but pins 1 and 5 are grounded.  Can you confirm that pins 1 and 5 are grounded?
    2. The reason that the output should go to zero is that the circuit input is being provide from pin 5.  If pins 1 and 5 are floating you will see the output go to a power rail.  I think this is what is happening in your case.
    3. You can use TINA SPICE to confirm this (picture and TINA file below).

    I hope this helps!  Best regards, Art Kay 

    ina149 floating input.TSC

    ina149 floating input.TSC

  • 0 in reply to Art Kay
    Mastermind 6445 points

    Hi, Kay-san

    Thank you for your support.

    The REF pin is connected to GND.

    The resistance between the operational amplifier input terminal and the REF terminal is higher than other devices.

    I have used more than tens of thousands so far, but there are 3 devices that work this time.

    Maybe ESD stress was applied to the device.

    cafain

  • 0 in reply to cafain
    TI__Mastermind 20097 points

    Cafain,

    1. Let me confirm:  You have used many (10,000+) devices in the past without issue.
    2. Now, you have failures.  How many device have failed?  How many devices are working / not working in your current manufacturing build?
    3. If you are doing a new manufacturing run and many of the devices are not behaving correctly, it is unlikely that they all were damaged by ESD.  If it is just one or two devices ESD (or other overstress) is a possibility.  
    4. Did you purchase the devices through an authorized source for TI devices?  Some vendors doing resale of TI devices are counterfeit devices.  Sometimes you can tell by comparing the packaging of a counterfeit to an authentic device that it is counterfeit.  For example, the marking is poor quality or different from the standard device.  Did you get these parts from an authorized source?  

    Best regards,

    Art

  • 0 in reply to Art Kay
    Mastermind 6445 points

    Hello Art san

    1. We have already shipped products incorporating more than 10,000 devices.

    2. 3 defects found during manufacturing process testing.

    3. Proven production line.
    　　It is conceivable that stress is applied by ESD in some line process.
    (Since then, no malfunctioning devices have been confirmed)

    4. Purchased from an authorized distributor in Japan.

    We plan to consult with TI-Japan on whether to conduct device analysis.
    Please let me know if you have any problems in the future

    Thank you.