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ADC3643EVM: Schematics and Pspice for TI

ClausD
Prodigy 10 points
Part Number: ADC3643EVM
Other Parts Discussed in Thread: THS4541, , THS4551, THS4521

Hi TI

I have looked at the Schematics for the ADC3643EVM to understand how the THS4541 is used with ADC364x in a single-ended to differential configuration. I could not find any information in the ADC366xEVM User's Guide on what components to remove or add to enable the THS4541 inputs.

The image below is cut-out from the ADV3643EVM schematic (sbar014a.zip).

Q1: Should the components in the red box be removed when using THS4541? The FDA has already centered the differential signal at the VCM level (0.95V).

I have modelled the circuit in Pspice for TI (see image below) to get a baseline and then work from that.

Q2: I would like some sort of refence to verify my measurements in Pspice for TI. E.g. what input signal to the EVM board will give a full scale ADC input (2.25Vpp)?

Q3: Can you provide a bit of background of the EVM design? I can see the glitch filter is modified compared to suggested design in the data sheet.

Thanks, Claus

  • 0
    TI__Mastermind 26990 points

    Ho Claus,

    The components in the red box can be removed and are not required when connecting the THS4541 amplifier.

    With the input amplifier network, the input signal would need to be roughly, 1Vpp or less in order to achieve the FS of the ADC.

    The glitch filter can be modified or removed depending on your application.

    What BW are you trying to use for this application? Do you have any AC performance requirements?

    Such as SNR, SFDR, etc? This will help provide some guidance here.

    Regards,

    Rob

  • 0 in reply to Rob Reeder
    Prodigy 10 points

    Hi Rob,

    Thanks for the quick reply.

    My application should initially be designed for DC to 10MHz. So far I have a loose requirement of an SNR of 75dB or better. Would that be reasonable out of a circuit like the ADC364xEVM?

    I read in a TI document that for frequencies below 5MHz the THS4551 should be considered instead of THS4541. Would that apply to ADC364x as well? If yes, what about the 5MHz to 10MHz range?

    Regards,

    Claus

  • 0 in reply to ClausD
    TI__Genius 14981 points

    Hi Claus,

    Can you share the document that you are referring to?

    Regards, Amy

  • 0 in reply to Amy
    TI__Mastermind 26990 points

    Hi Claus,

    Looking at the two THS devices, not sure where the 4551 amplifier would be a better fit. We can certainly provide a solution from DC to 10MHz using the THS4541. Please let us know if you want us to forward.

    Regards,

    Rob

  • 0 in reply to Amy
    Prodigy 10 points

    Hi Amy,

    In my notes I found a reference to "TIDUBS9A–August 2016–Revised October 2016". On page 5 and 16 it says to consider THS4551 for applications below 5MHz. I believe I have seen the same comment in another document as well. Just can't remember where.

    In "TIDA-00294-August 2014" on page 7 it says to consider THS4521 for applications below 5MHz. But on the THS4521 product page it pretty much says THS4551 is better device.

    Regards,

    Claus

  • 0 in reply to Rob Reeder
    Prodigy 10 points

    Hi Rob,

    Yes please. That would be great if you can forward a DC to 10 MHz solution. Thanks.

    Regards,

    Claus

  • +1 in reply to ClausD
    TI__Mastermind 26990 points

    Hi Claus, 

    See attached. Also, I spoke to the amplifier group and the THS4541 is the better choice.

    Regards,

    Rob


    ADC3683-30MHzFrontendEval_2022.pptx