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OPA858DSGEVM: The product I purchased doesn't work

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Prodigy 10 points

Part Number: OPA858DSGEVM
Other Parts Discussed in Thread: TDC7201

Tool/software:

Dear TI:

I recently bought your OPA858DSGEVM and want to use it with TDC7201 to conduct laser ranging experiments, but some problems have occurred. The output of my APD is shown in the first picture. The 1064nm beam is used and the maximum level output reaches 1.48V. I refer to the data sheet and the user manual. When I use a single power supply input, VCC uses 5V, and VEE is grounded, the output is only more than 200mv. When using dual power supplies VCC3V and VEE0.8V, the output is only 320mv. This does not conform to the principle that it can amplify 7 times in phase. Is there something wrong with the product I bought? I have read all the posts about OPA858DSGEVM in the forum and tried VCC+2.5V, VEE-2.5V, but it still doesn't help. I hope the engineer can reply to me after seeing it. Thank you. My project is very urgent.

  • 0
    TI__Mastermind 20810 points

    Hi,

    I wanted to run through a couple debug steps to see if we can find the issue. I would like to highlight that with the expected input signal of around 1.48V, the output will saturate as the device is in a gain of 7V/V. However, there does seem to be something wrong despite the concern of an overly saturated output. It would be good to take a step back and try turning the device on in its nominal configuration and confirm it is on properly. Could you set the device in a +/-2.5V supply and remove the input and output connections. I would like to confirm the Iq of the device to ensure it is not damaged. You should be seeing around 20.5mA being supplied to the device in a +/-2.5V configuration.

    Best Regards,

    Ignacio