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AM625: Power down sequence inconsistency between AM625 and TPS65219

Koichiro Tashiro
Mastermind 22915 points
Part Number: AM625
Other Parts Discussed in Thread: TPS65219,

Tool/software:

Hi,

My customer found that power-down sequence does not match between AM625 datasheet and TPS65219 TRM(SLVUCL0).
Below is AM625 datasheet Figure 7-6.


Suppose VDD_CORE is 0.75V, above waveform requires,
Waveform C and D are shut down, then waveform G goes off.
On the other hand, below is TPS6521902 power down sequence. Waveform G(Buck1 / 0.75V) is shut down at the same timing as Waveform C(Buck2, LDO3, LDO1) and Waveform D(LDO4).
Is this valid power down sequence?




Thanks and regards,
Koichiro Tashiro

  • 0
    TI__Guru**** 188979 points

    Hello Koichiro Tashiro

    Thank you for the query.

    Let me review the inputs and come back.

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    TI__Mastermind 22156 points

    Hi Koichiro,

    As shown in the AM62x datasheet, VDDSHV4/5/6 (waveform D) were designed to support power-up, power-down, or dynamic voltage change without any dependency on other power rails. All the remaining rails (except VDD_CORE and CANUART) can be turned OFF at the same time. 

    The main power-down requirement is for the CORE rails, if you are running VDD_CORE at 0.75V, then it must turn-OFF after VDDR_CORE. These are waveforms G and H. The power-down sequence configured on TPS6521902 meets this requirement. 

    Thanks,

    Brenda