Power Down Sequence of TPS6590377

prachi panse1

Other Parts Discussed in Thread: TPS659037

Hi,

As per the expected power down sequence for the AM572x processor, the 1.8V core supplies should go down after the PHY supplies. However, as per the ACT2OFF sequence of the TPS659037 PMIC, the 1.8V core supplies (SMPS supplies) go down before the PHY supplies (LDO3, LDO4). Please let me know why is this sequence different and if it is a cause of concern.

In the ACT2SLP sequence, the order is as expected. Can you also tell me why this different is present between the ACT2OFF and ACT2SLP sequences?

Regards,

Prachi

over 8 years ago

0 Karl Wallinger over 8 years ago

TI__Genius 16410 points

Hello Prachi,

This power-off sequence was defined jointly with the AM57xx team to be as short as possible to support the case of uncontrolled power-down. For sleep sequence, this is not a concern.

I don't think that the PHY supplies go down later than the 1.8V supplies. PHY is powered by LDO3/LDO4, and 1.8V is supplied by SMPS8 or LDO2, depending on the OTP version. In both versions, these are switched off at the same time.

Regards,
Karl

0 prachi panse1 over 8 years ago in reply to Karl Wallinger

Intellectual 980 points

Dear Karl,

As per the Power Down Sequence of TPS6590377ZWSR in the user guide, the LDO3 and LDO4 outputs ramp down 500us after the SMPS12, SMPS45, SMPS6, SMPS7, and SMPS8 supplies ramp down.

Below is a snapshot from the user guide for your reference:

Regards,

Prachi

0 Karl Wallinger over 8 years ago in reply to prachi panse1

TI__Genius 16410 points

Hello Prachi,

SMPS12, SMPS45, SMPS6, SMPS7, SMPS8 are not 1.8V regulators. However, I understand your question about the different power-up and power-down timing, so I'm discussing with the AM57xx team and will respond back with our answer.

Regards,
Karl

0 prachi panse1 over 8 years ago in reply to Karl Wallinger

Intellectual 980 points

Thanks Karl. Have you been able to find the reason?

0 Karl Wallinger over 8 years ago in reply to prachi panse1

TI__Genius 16410 points

Hi Prachi,

The discussion is ongoing. We will make sure the datasheet and sequencing are aligned.

Regards,
Karl

0 Karl Wallinger over 8 years ago in reply to Karl Wallinger

TI__Genius 16410 points

Prachi,

The AM572x datasheet is going to be updated to reflect the latest sequencing requirements. The PMIC sequence is in line with this update, so there is no issue using the current power-down sequence.

Regards,
Karl

0 prachi panse1 over 8 years ago in reply to Karl Wallinger

Intellectual 980 points

Dear Karl,

Thank you for the update.

Regards,

Prachi

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Power Down Sequence of TPS6590377