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INA 326 not working!!!

Purushottam Pawar
Intellectual 400 points

Hi,

I am using INA 326 instrumentation amplifier. I have connected it in bridge arrangement as shown in datasheet. But it is not working. 
I have checked it on TINA simulator where it works fine. But when I am testing it practically there is no output. 
I have attached circuit and pics of my board for reference. Please have a look and suggest.6888.INA 326.pdf

  • 0
    TI__Mastermind 25865 points

    Hello Purushottam,

    I recommend removing/disconnecting the potentiometer, R3, and R4. Then try grounding pin 2 and applying a voltage to pin 3 such that the ouput does not exceed the product of the gain (which is unknown...R5 is not specified in the schematic) and the voltage you place on pin 3. Please let us know the result.

  • 0 in reply to Pete%20Semig
    Intellectual 400 points

    Hi Pete,

    Thanks for your prompt reply.

    I removed the potentiometer, R3 and R4 as suggested, pin 2 connected to ground and applied input signal(0 to 500 mV) to pin 3. I have placed R5 with 100K, hence gain is 4.
    But still there is no response. I have checked it on 2 different boards and in both cases the result was same. Also 2 IC's are burnt during testing when I was increasing input signal from 0 to 1V.
    I have a Gas sensor whose signal I have to amplify.
    I feel that I am doing something wrong. Please advice with your opinion.
    Thanks,
    paddy

  • 0 in reply to Purushottam Pawar
    TI__Mastermind 25865 points

    Hello Paddy,

    Here are a few more suggestions:

    a) Try new devices (it sounds like the ones you have may be damaged)
    b) Verify that the supply voltage is present at pin 7
    c) Verify the ground connection at pin 4 of the device and at R2

    Please let me know the results.

  • 0 in reply to Pete%20Semig
    Intellectual 400 points

    Hi Pete,

    The supply voltage at pin no 7 and ground connections at pin no 4 and at R2 seems fine.

    I have placed a new device and checked with the arrangement suggested by you, i.e. pin no 2 connected to ground and input applied to pin no 3 and it worked fine.

    But when I have connected 1.2 V to pin no 3 and 1.1 V to pin no 2, it stops functioning. I think it is damaged because there is 0.7 V  coming on pin no 3 (even if input signal is 0 V) and output voltage is 1 V for all the time.

    Also the damage rate is too high. Till now 6-7 IC's are burnt during testing. 

    Please suggest if there is any alternate to do this and help me to figure out what I am doing wrong.

    Thanks, 

    paddy