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AM5K2E02: Power down sequence

Jack McCulloch
Prodigy 60 points
Part Number: AM5K2E02
Other Parts Discussed in Thread: AM5K2E04

Hi,

We are working on a prototype board with a AM5K2E02 processor. Our current power down sequence is to power down all rails simultaneously when input power is removed. 

We have measured the rails as they collapse and noticed that CVDD1 is greater than CVDD for roughly 2ms before it falls below CVDD. 

Is this likely to affect long term reliability of the processor?   

The other rails seem fine, but are there any others we should pay special attention to?

I've attached a screen shot of the scope waveforms, yellow trace is CVDD and blue is CVDD1.

Thanks,

Jack

  • 0
    TI__Guru**** 161600 points

    Hi Jack,

    Our current power down sequence is to power down all rails simultaneously when input power is removed

    You unplug the power supply from the board, right?  This is not a sw shutdown (i.e. from linux with poweroff command), correct?

    In this case I've performed the same measurement on K2E EVM (purple line is CVDD, blue line is CVDD1):

    You can see that both supplies power-down at the same time. So the measurement you show is the correct power-down sequence.

    To answer your question, IMO, yes, 2ms is not much so there is little possibility, but in long term this could affect the SoC reliability in some way, see Section 10.2.2 Power-Down Sequence from AM5K2E04 Datasheet.

    Make sure you comply with the power-up and power-down sequences.

    Best Regards,
    Yordan

  • 0 in reply to Yordan Kovachev
    Prodigy 60 points

    Thanks Yordan,

    Yes the power is removed from board to achieve shutdown.