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TPS65911: TPS65911 for G12 - LDO1 problem

Kamil Kazelle
Prodigy 140 points
Part Number: TPS65911
Other Parts Discussed in Thread: 66AK2G12

Hello,

we are using TPS65911AA2ZRCR as power supply for 66AK2G12 in very similar way as on evaluation board. We have problem with 1V8_LDO1 (see first picture). On startup edge there is a peak that violates maximum ratings of G12 (peak is about 2.1 V and maximum ratings for PLLs is 1.98V). We have measured also evaluation board and it is the same (see second picture). Is it not a problem? Is it safe to use it like that for G12? Is there some way how to fix it and what is the cause of that?

Thank you for answer

Best Regards

Kamil

   

  • 0
    TI__Mastermind 49301 points

    Hi, Kamil,

      Thanks a lot for using TI devices and reporting us the issue!

      If you're using the LDO1 for DVDD18 which is I/O voltage for 66AK2G12, it's safe and has no problem since DVDD18 max voltage can be 2.45V according to its specs; no need to fix it; but more cap can reduce it. We don't know the cause of that; we'll update by an Apps note when we find the cause. 

  • 0 in reply to Phil Yi
    Prodigy 140 points

    Hi Phil,

    actually we are using it also for all PLLs (AVDDA_ARMPLL, AVDDA_DDRPLL... AVDDA_UARTPLL) in the same way as on evaluation board. So it is probably a problem? Adding capacitance doesn't work, peak is just shifted in time.

    Thanks for advice

    Best regards

    Kamil

  • 0 in reply to Kamil Kazelle
    TI__Mastermind 49301 points

    Hi, Kamil,

      Since our evaluation board design has been verified working well with all connections; so, as long as you're using in the same way as on evaluation board then everything will be fine without any problem. Please let's know in case you do find any issues.