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TPS65218: TPS65218 DCDC5/6 output

Expert 1840 points

Replies: 6

Views: 1111

Part Number: TPS65218

Hi team

My customer wants to know maximum output current when it backup for RTC.

Please let me know follow the questions.

1.Is this correct understanding, if Vcc supply will be shut down, the DCDC5/6 will supply to RTC as backup from coin cell?
2.In the datasheet, the output current of DCDC5/6 discribed the 100uA when it is backup. How do you test measure the output current?
Would you send me if you have the figure of circuit?

Best regards

Hayashi

  • Thank you for posting your question on TPS65218 device in the e2e forum. Your thread has been assigned to the expert within TI, who will reply to this thread as soon as possible and attempt to answer your question.

    Thanks & Best Regards,

    Brian

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  • In reply to Brian Berner:

    Hayashi,

    1. Yes, if IN_nCC pin is pulled low, DCDC5/6 will be powered from coin cell.
    2. Not sure what you are looking forhere. To check output current, connect coin cell and Pull IN_nCC low and slowly increase the load current to check when PGOOD_BU is low.

    Regards,
    Jay
  • In reply to Jayanth Kruttiventi:

    Hi Jay

    Thank you for your reply.
    But I still do not understand #2 yet.
    Would you tell me how much the value of resistance is it?
    And, in the case of backup, is it reasonable to say that the output current of this device is 100 uA?

    Best regards
    Hayashi
  • In reply to Hayashi:

    Hayashi,

    The maximum output current is 100uA while running off of the coin cell. The typical output current is 10uA.

    The reason why I think we are not sure what you are looking for is that the amount of current that will be supplied to the RTC depends on how much current the RTC itself pulls.

    The method Jay described can be used to find the max current. In that scenario you keep decreasing the resistance of your load in order to keep increasing the current being pulled from the PMIC and you will find a certain point where the current pull is too high and the PMIC can't supply the voltage required.

    If you want to know how much current the RTC is going to pull it will be more difficult.

    Thank you,
    Nick

    Thank you,
    Nick Jakse
    --------------------------------------------------
    Find the right power solution for your processor or FPGA. Visit www.ti.com/SoCPower today!

  • In reply to Nick Jakse49:

    Hi Nick

    I have a new question about TPS65218.
    I think that it is good to describe only the maximum value of the output current in the data sheet, but why is the typical value listed?
    Please let me know if there is any application that assumes something.

    Best regards.
    Hayashi
  • In reply to Hayashi:

    Hayashi,

    I am not sure where the typical value comes from but I think it is likely that you get better efficiency at 10uA.

    Thanks,
    Nick

    Thank you,
    Nick Jakse
    --------------------------------------------------
    Find the right power solution for your processor or FPGA. Visit www.ti.com/SoCPower today!

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