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TPS659037: TPS6590378ZWSR additional supply , unused SMPS

thomas mlynek
Prodigy 60 points
Part Number: TPS659037

Hello,

I use TPS6590378ZWSR as  supply for AM574x with 3V3 as main supply.

together with 1x DP83867 for Gigabit Ethernet and 1x DP83822 for 100Mb Ethernet, needed seperately,

as I dont use PCIe and HDMI there is some current ability on LDO4 1.8V which I want tu use to supply both PHYs on 1.8V (67mA DP83822supply at 1.8V completely,  and 24mA VDDIO of DP83867 approx)

can I use free programmable SMPS 9 for 1.0VDD1P0 108mA  and SMPS7 for 2.5VDDA2P5 ?mA   for the DP83867 Eth PHY  as they are not used for processor supply in this concept

any restrictions or doubts to do this?

many thanks & Regards, Thomas

  • 0
    TI__Genius 10000 points

    Thomas,

    Hi, you can use the unused SMPS rails to supply other items under the following conditions:

    1. You have I2C capability to enable the extra rails at the desired voltages

    2. The devices supplied by these unused SMPS rails can be powered up after the power up sequence programmed in the PMIC

    If there is no power sequence violations by enabling the extra rails after everything else has turned on, then there is no issue using them.

    Thanks,

    Nastasha

  • 0 in reply to Nastasha
    Prodigy 60 points

    Hello Nastascha,Thanks for the Info,

    ad 2) does this mean the need of implementing some switching device to separate- in my case DP83867 supplys- as long as the PMIC Voltage is programmed and on the desired level to avoid  Problems with SMPS default levels which might be to high ?

    how's About my first Question:

    as I don’t use PCIe and HDMI there is some current ability on LDO4 1.8V which I want use to supply both PHYs on 1.8V (67mA DP83822supply at 1.8V completely,  and 24mA VDDIO of DP83867 approx.)

     

    many thanks, kind regards, Thomas

  • 0 in reply to thomas mlynek
    TI__Genius 10000 points

    Thomas,

    What I mean by my #2 comment is that any unused rails in the TPS659037 can be used for powering additional items, however, you will see in the user's guide for the device, that the additional rails (SMPS7 and SMPS9) are not included in the power up sequence. This means you will have to turn them on (through I2C) after the power sequence completes. You can turn them on to what ever voltage you need, the default is set to 0V.

    The thing you need to consider is if there is any issue in your system by turning on the DP83867 supplies after all the other rails are enabled. If they are peripherals, it probably doesn't matter. The important thing is that the AM57x sequencing requirements are still met.

    In regards to your questions about LDO4, it is a similar case as above. If there is enough available current on LDO4, you can combine some of the processor rails from a power perspective. However, they can only be combined if they are intended to turn on at the same time in the AM57x power sequencing requirements. They must be powered separately if they need to turn on as separate times.

    Thanks,

    Nastasha