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BUF20800-Q1: Analog/Digital power supply current

Nam, Dino
Expert 5775 points
Part Number: BUF20800-Q1

Hello team,

At datasheet,

1. Analog power supply current is max 28mA under no load. If under full load, How can I estimate max supply current?

2. Digital power supply current is max 100uA under no load, two-wire bus inactive. If under full load, two-wire bus active, How can I estimate max supply current?
   =>Digital power supply : 3.3V. The 3.3V power supply of customer is not enough to cover their whole system.

Please review and let me know your opinion.

Thank you.

  • 0
    TI__Expert 5775 points
    Dear team,

    Is there any update on this request?

    Thank you
  • 0 in reply to Nam, Dino
    TI__Guru 58215 points

    Hello Dino,

    Please excuse the late response on your request.

    For the digital supply, the current is dependent on the frequency you are using to communicate with the part and in addition you will have some current for the pull ups if they are connected to the same supply. Nevertheless, there should not be more current than few mA during communication. Do you think that it is necessary to change the gamma buffer setting very often?

    For the analog supply, the maximum current is dependent on the output current as well as on the voltage on the outputs. If the output voltage is below the set voltage, the output needs to source current and then the full output current is coming out of the analog supply, so if all outputs are sourcing, the sum of the maximum output currents is the maximum supply current.

    Nevertheless, keep in mind, if the output is higher than the set voltage, the output is sinking current and then the current will go into GND and the analog supply will not source any current.

    Best regards,

    Brigitte

  • 0 in reply to Brigitte
    TI__Expert 5775 points
    Hi Brigitte,

    Thank you for your comment. the customer do not change the gamma buffer setting often.
  • 0 in reply to Nam, Dino
    TI__Expert 5775 points
    Hi Brigitte,

    I have moer questions.

    Would you please lel me know output tolerance as changing temp(-40C to 105C) or load condition?
    For load condition,There is graph of output voltage per output current at datasheet 5 page Fig4, but the customer want to speccific number like %. If possible, Please let me know output tolerance number or % as changing temp or load condition?

    Thank you.
  • 0 in reply to Nam, Dino
    TI__Guru 58215 points

    Hello Dino,

    Please excuse the late response.

    The output voltage is dependent on the load condition as you can observe in Figure 4. We cannot give a percentage for the whole load range because it is not fully linear as you can observe in this figure. In addition, the figure shows that the tolerance is dependent on the code as well. If the output needs to source current, the tolerance is different than for sinking current.

    The output accuracy is given with +/- 50mV with no load. Over temperature it is typically +/-25mV.

    The load regulation is given with 1.5mV/mA.

    Which concerns does your customer have? Why does he need percentage numbers?

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Expert 5775 points
    Hello Brigitte,

    Thank you for your reply.
    There is no specific concern about that. They just need a data for approval document to submit to their End customer.
    I will have a meeting with your comment and will contact you again if more information is needed.

    Thank you.