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DAC7811: About DAC7811 circuit

Expert 2630 points

Replies: 10

Views: 399

Part Number: DAC7811

Hi team,

 I am considering replacing another maker's multiplying DAC with DAC7811
 at my customer.
 Please see the attached file.

DAC_circuit.xlsx
 I think that DAC7811 is usable and the Cf can be used not only for phase
 compensation but also for LPF by increasing Cf value.
 
 Is my understanding correct?

 If you have any concerns about that please let me know.
 
Sincerely,
Tsuyoshi Tokumoto

  • Hi Tsuyoshi-san,

    Thank you for your query. I don't see any problem in using Cf for creating a first-order LPF. However, if you need a proper BW limit, I would recommend using another LPF stage after the transimpedance amplifier.

    There is a previous E2E post that talks about the multiplying bandwidth and a simplified model of the MDAC. You can use that to replicate the filter behavior by changing Cf.

    e2e.ti.com/.../671207

    Hope that answers your question.

    Regards,
    Uttam Sahu
    Applications Engineer, Precision DACs
  • In reply to Uttam Sahu:

    Hi Uttam-san,

    Thank you very much for your prompt reply.
    I will use your advice as a reference from now on.


    Thank you and best regards,
    Tsuyoshi Tokumoto

  • In reply to Uttam Sahu:

    Hi Uttam-san,

     Please let me ask you an additional question.

     My customer is considering using the DAC7811 now.
     In his current design situation, the DAC 7811 needs to be controlled by a serial
     interface with 24-bit width.
     I believe that the DAC7811 will be controlled correctly by placing valid data
     in the lower 16bits.
      *Please see the attached file.

    Dac7811_input.xlsx
    Is my understanding correct?

    Thank you and best regards,
    Tsuyoshi Tokumoto

  • In reply to tsuyoshi tokumoto:

    Hi Tsuyoshi-san,

    I think this scheme should work but I need to test it on the EVM before I can confirm. I will get back by next week.

    Regards,
    Uttam
  • In reply to Uttam Sahu:

    Hi Uttam-san,

      Thank you very much for your prompt reply.
      I really appreciate your cooperation!

      I look forward to your answer.

    Thank you and best regards,
    Tsuyoshi Tokumoto

  • In reply to Uttam Sahu:

    Hi Uttam-san,

     I would appreciate it if you could share the test result on the EVM with me.
     I apologize for rushing you, but I would like to reply to my customer
     about this question by the end of the week.

    Thank you and best regards,
    Tsuyoshi Tokumoto

  • In reply to tsuyoshi tokumoto:

    Tsuyoshi-san,

    I will upload my findings tomorrow.

    Regards,
    Uttam
  • In reply to Uttam Sahu:

    Hi Uttam-san,

      I appreciate your understanding and cooperation.
      I look forward to your findings.

    Thank you and best regards,
    Tsuyoshi Tokumoto

  • In reply to tsuyoshi tokumoto:

    Hi Tsuyoshi-san,

    I tested it on the EVM. It works. In a 24-bit SPI frame, the DAC8811 takes the last 16 bits.

    Hope that answers your question.

    Regards,
    Uttam
  • In reply to Uttam Sahu:

    Hi Uttam-san,

      Thank you for the good news!
       I shared your answer with my customer.
       I appreciate your cooperation

    Thank you and best regards,
    Tsuyoshi Tokumoto

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