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TPS65220: Random Power up Issue

Aditya Patil
Prodigy 50 points
Part Number: TPS65220
Other Parts Discussed in Thread: AM6442

Hi Team,

We are using the “TPS6522053RHBR” PMIC and the “IS46LQ16512A-062BLA2” DDR4 IC on our custom AM6442 board. We have observed that, in some cases, the board fails to power up as the PMIC does not generate the output voltages. Occasionally, the outputs appear after one or two power-up attempts.

From a previous ticket (https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1586525/am6412-am6412-1-1v-and-1-8v-boot-sequencing-question), it was noted that the ISSI DDR4 device may cause backfeed voltage on Buck3 (1.1 V). We are noticing a similar issue on a few of our boards; however, it is not consistent across all units.

Please find the attached oscilloscope waveforms for your reference. Kindly advise on the possible root cause and recommended solution to resolve this issue.

Thank you,  
Aditya

FAILING_3TIMES.pngFAILING_ONCE.pngNOT_FAILING.pngFALING_2_TIMES.png

  • +1
    TI__Genius 15715 points

    Hi Aditya,

    Thank you for posting on E2E. As you mentioned this is a known problem with ISSI DDR4 memory. Unfortunately at this time there is no clean answer as the RV fault is not a maskable fault. It is there for protection for short circuit conditions to ensure no damage occurs, there is no direct workaround.

    We recommend disqualifying any ISSI DDR4 memory that causes this issue.

    A potential workaround, is to ensure the rails turn on simulataneoulsy. There is no violation from the memory perspective on the timing of the rail power ups and it helps to mask the RV fault seem by the PMIC when all rails are enabling simulateneously. 

    Regards,

    Brandon