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LM10500: PowerWise interface documentation & long term support

Tom Oldbury (TTX)
Prodigy 40 points
Part Number: LM10500
Other Parts Discussed in Thread: LM10010, TPS62136

Hi all,

I have a requirement for an adjustable core supply voltage for a SoC.  The core supply voltage will be controlled by an external microcontroller from about 0.9V to 1.1V.  Crucially, the product has limited board area available so we would prefer an integrated solution.

I found the LM10500 which seems to be ideal for this application, and it supports PowerWise Interface.

However, I cannot find any documentation on this protocol, other than it predating the National-TI merger and having the support of ARM.  Since we are not using a SoC that natively supports PWI, we need to implement the protocol in software.  The best documentation I found was a bit-banged protocol implementation,  which would be a good resource if we could also compare it against a protocol spec.  The National pages and pwistandard.org are down.  But archive.org shows there was never any documentation at pwistandard.org - how odd!

The secondary issue a member of the engineering team raised was that given the age of this device and the relative dearth of PWI capable TI power management ICs, is this a long-term solution (5+ years) or would TI be expecting to NRND this part in the near future.  If so, is there an alternative part we could use.

Kind regards

Tom Oldbury,  Snr Engineer Thermoteknix Systems Ltd.

  • 0
    TI__Mastermind 23105 points

    Hi Tom,

    You are right all the major PWI sites and their links are not working anymore. Looking at the timeframe, it seems to be around 2003-2007 when most ICs with this technology were released. I could not find a lot of information on this protocol except a few technical documents.

    Can you please provide the input voltage min-max range and the load current requirements for this supply? I would recommend looking for a newer IC which can be used for the adaptive voltage scaling purposes.

    Thanks,

    Amod

  • 0 in reply to Amod Vaze
    Prodigy 40 points

    Hi Amod,

    We do have rather unusual requirements due to being powered off 4 x AA and targeting maximum efficiency so want to avoid a second step-down converter.

    Our input range is 3.5V - 7.35V and output range is 0.9 - 1.1V at 3.5A.   The load current is a peak figure, we expect steady state current around 1A.

    At the time of posting, I could not find an alternative TI solution.

    Kind regards

    Tom

  • 0 in reply to Tom Oldbury (TTX)
    TI__Mastermind 23105 points

    Hi Tom,

    Thanks for these details. In this range, you can use TPS62136 which meets your input/output specification and should provide very high efficiency with the PFM/PWM mode operation. And, you can use the LM10010 in conjunction to adjust the output voltage. Hoping there is some PCB space for this solution. Let me know if you have further questions. 

    Regards,

    Amod

  • 0 in reply to Amod Vaze
    Prodigy 40 points

    Hi Amod,

    Thanks for the response and the device suggestions.  I will consider it, although ideally we would keep this to a one-device solution.

    Does this mean you are *not* recommending the LM10500 as a design going forward?  As provided we could source the necessary documentation for this part, we believe it would be quite a suitable part and it is currently listed as actively supported.

    However, if we cannot find the PWI documentation, then we will not be able to use it.

    Thanks,

    Tom

  • 0 in reply to Tom Oldbury (TTX)
    TI__Mastermind 23105 points

    Hi Tom,

    The recommendation I made is an alternate option with newer part with better efficiency which seemed like the key consideration. In parallel, I am trying to find out more about PWI documentation from internal contacts but have not found any information yet. For a single device solution, LM10500 is a good fit for your application. I will keep you updated ideally within a day.

    Thanks,

    Amod

  • 0 in reply to Amod Vaze
    TI__Mastermind 23105 points

    Tom,

    Unfortunately there is no additional information available on the PWI 1.0/2.0 specification. Also given that most other PWI parts have now been discontinued, I would recommend checking the alternative option I had proposed. Hope that works out for you. Thank you for your patience in this matter.

    Thanks,

    Amod

  • 0 in reply to Amod Vaze
    Prodigy 40 points

    Hi Amod,

    Thanks for getting back to me.  OK, that's a shame but that's the way it goes.  I think the two-device solution you suggested will be best for us then,  thanks for the research there.  In the meantime, if anyone becomes aware of PWI1.0/2.0 documentation,  I'm listening.

    Kind regards

    Tom