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OPA858DSGEVM: Mouser Tech Request - 504429

Thomas Rosendahl
Intellectual 390 points

Part Number: OPA858DSGEVM

Hi,

We have a customer who ordered evaluation board OPA858DSGEVM from Mouser.

They have reported the following issues: 

    "The appearance of the device is complete and defect free, but the gain

      should be 7 times. Currently, the laboratory has measured that it is only

      1 time. We use a waveform generator to give IN+a 20mV, 1MHz sine wave. The

      input and output (IN+and OUT) waveforms are exactly the same, with no

      change in amplitude, indicating that the gain is only 1."

Could you please advise if there is a way they can test or trouble-shoot this board?

Kind regards

Thomas Rosendahl

Mouser Electronics

S/O 504429

  • 0
    TI__Mastermind 32355 points

    Hello Thomas,

      If you are using the EVM in default configuration with the scope set to 50 ohm impedance, then your output will be attenuated due to the output resistors and 50 ohm to ground from the scope:

      To check this, can you change the impedance on the scope from 50 ohm to high impedance. Or you can probe directly at the output of the amplifier, which we only recommend doing this with a very low capacitance probe or after a small isolation resistor to avoid creating an unstable system leading to oscillations. 

    Thank you,

    Sima