A1989 / 820-0850-A PPVCCEDRAM_S0_CPU low

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  • cruiser_
    Senior Member
    • Nov 2019
    • 124
    • Ireland
    #1

    A1989 / 820-0850-A PPVCCEDRAM_S0_CPU low

    Struggling to get this board working...

    I noticed it had PPVCCEDRAM_S0_CPU at 0V (with a microsecond spike over 1V) ; enable ( PVCCEDRAMS0_EN_FILT_BUF @ 1.8V) for U7710 was present & had no PVCCEOPIO_EDRAM_PGOOD.

    I replaced U7710 from a 820-01041 board (U8110) - same chip, ISL 95870hruz.

    Getting PVCCEOPIO_EDRAM_PGOOD at 0.7V but PPVCCEDRAM_S0_CPU only at ... 50-60 mV.

    Thought ok, maybe the chip was bad. Took it from yet another board - same behavior. Injecting 1V to this rail only pulled 500mA...

    Is it possible at all that at the early start the T2 (or PMIC?) requests this rail to be at such a low output? What am I missing?
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