TPS659039-Q1: The TPS659039 power-up sequence

user3378603

Part Number: TPS659039-Q1

Hi，

The SOC function modules related to power supply from VDDA_1V8_PHY are not used.
We are testing the TPS659039 power-up sequence and found that the power-on sequence of LDO3_OUT is abnormal.（Note that there is a voltage step before power-on.）

The SMPS_7 of the PMIC output is used for the CORE_VDD supply of the SOC, as shown by the green line;（This voltage step seems to be related to the power supply of CORE_VDD）
Another LDO3_OUT is used to power the VDDA_1V8_PHY of Soc, as shown by the yellow line;

Can you give some advice and how to solve it?

over 6 years ago

0 Nastasha over 6 years ago

TI__Genius 10000 points

Feng,

Is LDO3_OUT floating since you are not using VDDA_1V8_PHY? I would start by making sure there is no connection between the output of SMPS7 and the output of LDO3.

Thanks,
Nastasha

0 user3378603 over 6 years ago in reply to Nastasha

Intellectual 1000 points

Hi Nastasha，

There is no connection between the output of SMPS7 and the output of LDO3. I think it should be through the internal past of the SOC chip.

LDO3_OUT has been connected to the SOC's VDDA_1V8_PHY, I mean the module inside the SOC that needs to use VDDA_1V8_PHY is not used, as shown below。

0 Kevin LaRosa over 6 years ago in reply to user3378603

TI__Genius 17380 points

Hi Feng,

This is expected behavior and not an issue for PMIC or processor.

This is documented in the processor errata (item i931): www.ti.com/.../sprz398i.pdf

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TPS659039-Q1: The TPS659039 power-up sequence