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OPA2188AIDT noisy

FREDERIC SZTRENACZKA
Prodigy 30 points
Other Parts Discussed in Thread: OPA2188

Dear Forum,

We are using the OPA2188AIDR into an application.

We measure the gage displacement when we drive a piezo.

The system is in close loop, and some time we have some spikes after the error amplifier.

The OPA2188 is used to construct and amplify the gage signal. We suspect the following circuit OPA2188,

if we touch the device with a finger, it will be very sensitive.

If we place a mini "shield" with a copper foil connected to earth top of the body of the circuit,

we minimize noise and spikes due to esd.

Is this how to configure the circuit is normal?, or so we have another problem relating to it?.

How to reduce spikes or ESD? problem. Have we to add extra components around the OPA. 

Thank you for your valuable information.


Best regards.

Frédéric S

  • 0
    TI__Guru 60610 points

    Frederic,

    Could you please provide us with the circuit schematic you use as well as a scope picture of the noise spikes you refer to.

    This can be done by clicking on Insert Media or Insert File buttons shown above.

  • 0 in reply to Marek Lis
    Prodigy 30 points

    Hello Marek,

     

    Here after the principle of the OPA2188 into a closed loop.

    On the scope the blue one : is normally a triangle Voltage applied on the piezo.

    On the yellow side : the output after the error op-amp.

    We look a very noisy signal.

    Thank you for your expertise.

    Best regards.

    Frédéric

  • 0 in reply to Marek Lis
    Prodigy 30 points
    We also have another phenomenon that occurs on the card: the "noise" is generated and amplified by itself something. the disturbance is temperature.
    The appearance of oscillations temperature range is between 40 and 50 ° C.
    How do you analyze this?
    Thank you for your réponce
    best regards.
    Frédéric