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RM57L843: Can RM57L843 be powered with TPS65381AQDAPRQ1 companion chip?

Dmitri Chtchvyrkov
Prodigy 130 points
Part Number: RM57L843
Other Parts Discussed in Thread: TPS65381A-Q1

In our new design we've decided to move to RM57L843 part.
I could not find any information about current consumption of that chip.
I wonder if TPS65381AQDAPRQ1 companion chip can support that part - does it have enough current capability to do it?

Thank you,

Dmitri Chtchvyrkov.

  • 0
    TI__Guru 59540 points

    Hello Dmitri,

    Unfortunatly, the current consumption of the RM57x device is too much for the TPS65381 PMIC. This doesn't mean it can't be used to take advantage of its safety related features (Q&A WD, ERROR pin monitoring, etc), but additional circuitry may be needed to add additional current supply capability. I have CCed an associate from our PMIC team to, hopefully, provide more details on how this can be done.

    By the way, the max current for the RM57 is provided in section 5.7 of datasheet SPNS215C.pdf. It can be retrieved at this link:

    For reference, this is the table from rev.C of this datasheet:

  • 0 in reply to Chuck Davenport
    Prodigy 130 points
    Dear Chuck,
    Thank you very much for your help. We'll have to think then how to maintain the safety requirements with additional circuit.
    Regards,
    Dmitri.
  • 0 in reply to Chuck Davenport
    TI__Mastermind 20590 points

    Hi Dmitri,

    The TPS65381A-Q1 is very scalable on the VDD1 core supply since the integrated rail is an LDO controller with independent voltage monitoring (VMON).  Attached is a PDF showing how to use an external DCDC for the core rail supply instead of the LDO1 controller FET.  Basically you can derive the core rail either with DCDC directly from the VDD6 pre-regulator if the efficiency is high enough and the loading on the other rails low enough, or you can have the DCDC directly from your main supply down to the core.  In either case the VDD1_SENSE pin is then used to monitor the core rail (same as using the VDD1 LDO controller) but the VDD1_G is left open since the LDO isn't used. 

    3173.2017-02-03 TPS65381A-Q1 with External DCDC.pdf

    Best Regards,

    Scott

  • 0 in reply to Scott Monroe
    Prodigy 130 points
    Hi Scott,
    Thank you very much. These are excellent proposals to solve functional safety issues as well as thermal problems. In our current design they were not severe, but with a new chip, even if TPS could handle the current, we would have to look very close on heat dissipation.
    I appreciate your help very much.
    Regards,
    Dmitri.