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EVMK2H: Power-up sequence does not align with datasheet

Koichiro Tashiro
Mastermind 22020 points

Part Number: EVMK2H

Hi,

My customer is asking power-up sequence on EVMK2H.
According to 66AK2Hxx datasheet, ether two power-up sequencing is acceptable.

The first sequence stipulates the core voltages starting before the IO voltages as shown below.
1. CVDD
2. CVDD1, CVDDT1, VDDAHV, AVDDAx, DVDD18
3. DVDD15
4. VDDALV, VDDUSB, VP, VPTX
5. DVDD33

The second sequence provides compatibility with other TI processors with the IO voltage starting before
the core voltages as shown below.
1. VDDAHV, AVDDAx, DVDD18
2. CVDD
3. CVDD1, CVDDT1
4. DVDD15
5. VDDALV, VDDUSB, VP, VPTX
6. DVDD33

But EVMK2H power-up sequence does not follow them.
Below figure is page#6 of EVMK2H schematics
Power-up sequencing is something like this;
1. CVDD
2. CVDD1
3. CVDDT1
4. DVDD33
5. VDDAHV(0.85V)
6. VDDAHV(1.8V)
7. DVDD15

Is this acceptable ?




http://wfcache.advantech.com/www/support/TI-EVM/Rev4_0/Schematics_PDF/K2H_K2EVM-HK_SCH_A104_Rev4_0.pdf

Thanks and regards,
Koichiro Tashiro

  • 0
    TI__Guru**** 161600 points

    Hi,


    You must follow the datasheet.

    As for the EVMK2H not following the power-up sequence, have you checked Table 11-2. Core-Before-IO Power Sequencing? There are some clarifications there, for example:
      "CVDD1 and DVDD18/ADDAVH/AVDDAx may be enabled at the same time but do not need to ramp simultaneously. CVDD1 may be valid before or after DVDD18/ADDAVH/AVDDAx are valid, as long as the timing above is met."

    I've not checked thoroughly and compared to EVMK2H sequence, but I think the EVM is within datasheet specs regarding power-on sequence.


    Best Regards,
    Yordan

  • 0 in reply to Yordan Kovachev
    TI__Mastermind 22020 points

    Hi Yordan,

    OK. I understood the datasheet sequence needs to be followed.

    For EVMK2H, I do not agree the EVM is within datasheet specs.
    In any scenarios in datasheet, DVDD33 ramps up the last, but it is not in EVM.

    Thanks and regards,
    Koichiro Tashiro

  • 0 in reply to Koichiro Tashiro
    TI__Guru**** 161600 points

    Hi,

    This may not be as strict of a rule (i need to verify it), nevertheless, you MUST follow the datasheet recommendations and ensure the power-on/power-off sequences are as described in the document.

    Best Regards,
    Yordan