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DAC 34H84 EVM and SPARTAN SP605

Prodigy 65 points

Replies: 7

Views: 1044

Hello,

I am trying to connect a DAC 34H84 EVM with a SPARTAN SP605 FPGA board via tha TI  DAC-FMC  Adapter rev.D and I have a couple of questions.

1) I am trying to physically connect the DAC-FMC Adapter to the DAC34H84EVM but the connectors do not seem to be compatible. I attach the following pictures to ensure that I should try to connect the two boards  without ruining any of the connectors. Both boards are rev. D

2) Since I am using a SPARTAN SP605 board I want to feed the DAC with data and DATACLK. As I understood the DACCLK is provided to the DAC via the CDC module which in turn is fed in external clock for reference. Is this true?

3) Apart from the DATA and DATACLK should I expect to have as input to the FPGA the FPGA_CLK providing a DACCLK copy? Should this be used as  the REF CLK for my FPGA design creating the DATA?

4) Concerning the remaining ports such as SYNC, PARITY and ISTR should I feed a signal to them or can they just stay unconnected?

5) Since I am willing to output DC currents which procedure should I

follow to bypass the output transformers and have a DC coupled output? 

Thank you very much,

Christos

7 Replies

  • Christos,
    1. The connector may not work well. We will need to send you a replacement EVM. I will contact you offline.
    2. Correct.
    3. This depends on firmware implementation. Most of the firmware implementation requires a reference clock to ensure system synchronization.
    4. Please refer to the datasheet for detail on the control signal usage. There is an app note associated with these control signals.
    www.ti.com/.../slaa584
    5. Refer to the following app note for detail on DC termination.
    -Kang
  • In reply to Kang Hsia:

    Dear Kang,

    thank you very much for your immediate response!

    When you say that the connector may not work well you mean that the specific board is faulty or that the revisions between the EVM board and the FMC adapter are not matching?

    I am asking this because we are working on a project with an upcoming deadline and it is crucial to know if I could try to connect the two boards or else speed up the process of sending you back the EVM and getting a new one as soon as possible.

    For the other questions your answers were very helpful and I will follow the app note you sent me.

    However, searching a bit I did not find any part describing how to ensure that the outputs could be DC coupled. To clarify a bit the discussion, for our application we want to produce prgrammable (via the FPGA board) DC output currents that change their DC level every 200us and thus the transformer would probably kill any DC output.

    Thank you again for your help! Looking forward to hearing back from you,

    Christos
  • In reply to Christos Spatharakis:

    After searching I found this wiki page and it seems like we have an EVM board with the wrong connectors.

    e2e.ti.com/.../3316.dac348x-hsmc-connectors

    Could you please confirm that this is the case and if so initiate the replacement procedure? I am just asking again because we have very tight timing requirements for this project and we would like to be able to test the FPGA-DAC connection as soon as possible.

    Finally, I have one more question:for using the full functionality of the C,D channels as well as for bypassing the transformers to achieve DC-coupled output many forum answers indicate removing and installing several resistors. Should this be done manually by us or could you send us an EVM with the desired configuration?

    Thank you very much,

    Christos
  • Guru 54100 points

    In reply to Christos Spatharakis:

    Christos,

    Please send a shipping address and contact phone number and I will ship you another DAC34H84EVM ASAP.

    Regards,

    Jim

  • In reply to jim s:

    Dear Jim,

    thank you for your immediate response, I sent you a private message with the details.

    As far as the removing and installing of resistors is concerned, do you have any advise or comment?

    "Finally, I have one more question:for using the full functionality of the C,D channels as well as for bypassing the transformers to achieve DC-coupled output many forum answers indicate removing and installing several resistors. Should this be done manually by us or could you send us an EVM with the desired configuration?"

    Thank you very much,

    Christos
  • Guru 54100 points

    In reply to Christos Spatharakis:

    Christos,

    Do to current availability, I can send a DAC34SH84 (1.5 Gsps DAC) instead of a DAC34H84 with the transformers removed. Will this work for you?

    Regards,

    Jim

  • In reply to jim s:

    Dear Jim,

    Our application requires a DAC that will get input from an FPGA and give as an output DC currents that will change to a different DC level every 200us (5KHz). The output currents we want to achieve are in the range of 5-30 mA (if needed we can reduce this dynamic range to some extend). This need of DC coupling is the reason we need to have the transformers bypassed.

    We purchased DAC34H84 after consulting a TI expert and deciding that this was an EVM that would fit our needs. Do you think that the DAC34SH84 would meet these requirements?

    If yes we are happy to work with the DAC34SH84 EVM instead, of no is there another DAC that could meet our requirements in a better way?

    Thank you again,
    Christos

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