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Original question:

AM5726: Power supply connections

AM5726: Powering AM5726

Christoph Dr. Stiebel
Prodigy 115 points
Part Number: AM5726
Other Parts Discussed in Thread: TPS659037

I want to power an AN5726 without GPU, EVE and IVA. According to SLIU011F page 4

I must connect the unused power pins to 1.06 V. Do I need to use the high current SMPS4 in parallel with SMPS5 for that purpose or is a LDO output (per example LDO2) sufficiant for that purpose. I want to use SMPS4 and SMPS5 to power a FPGA. How big is the current for this unused power pins?  

  • 0
    TI__Guru 51695 points

    The Power Management IC (PMIC) is pre-programmed for specific voltage levels and sequences.  I'm not sure you can change voltage levels/sequences for SMPS4, SMPS5, and LDO2.  Is that your expectation?

  • 0 in reply to Robert Eschler
    Prodigy 115 points

    I am quite shure I can change the powering sequence and the voltage levels of the PMIC, but I have to proove it. My question is: What current do I I need to satisfy the unsed core voltages for
    the GPU, the EVE and the IVA. Do I need additional buffer capacitors or is the 1 uF at the output of an LDO enough.

  • 0 in reply to Christoph Dr. Stiebel
    TI__Guru 51695 points

    At high temp (125C), the leakage on those core can still be very high (even if unused can be multiple amps) - thus it is still recommended to connect as recommended in the diagram.  You can certainly reduce much of the decoupling capacitor - as there wont be any switching activity.

  • 0 in reply to Robert Eschler
    Prodigy 115 points

    After reading many post within this forum, I know that I can not change the startup voltages or the bootup sequence of the TPS659037 chip. All I can do ist to select the right OTP version in my case it will be the TPS6590378ZWSR. With this chip according to manual of the Sitara SPRS953G page 376  for the unused power supplies this wiring should also be possible:

    Doing so I should have 3 DC/DC conterters free for other stuff SMPS4/SMPS5 (powering up first with 1.05 volt but can be changed later via I2C) and SMPS7 and SMPS8 (powering up first with 0 volt but can be changed later via I2C). Is that correct?

  • +1 in reply to Christoph Dr. Stiebel
    TI__Guru 51695 points

    This is the picture/OTP you should use, yes?

    The modified drawing you provided does not supply correct voltage to DSP_EVE, IVA, and GPU.