TPS65910: TPS65910:About the output waveform of VAUX2

user3976270

Part Number: TPS65910
Other Parts Discussed in Thread: AM3354

I use a combination of TPS65910A31A1 and AM3354 in the product.


The output of VAUX2 of TPS65910 as shown in the attached figure Output with timing and voltage different from the setting.


The settings of TPS65910 are the same as Table 2 of SWCU093F. (VAUX2 = 3.3 V)


1.Is this a specification of this IC?

2.If it is not a specification, is there a way to improve it by setting etc.?

BestRegards

over 6 years ago

0 Richard Solarski over 6 years ago

TI__Genius 10885 points

Hello,

This is not a specification of the IC. The scope capture shows VAUX2 enabling properly 2ms after VDDS_DDR, indicating that the initial voltage on VAUX2 is being supplied from a separate regulator.

The voltage starts increasing ~10ms before VDDS_DDR, which is likely right around the power assertion event.

This indicates there is a parasitic path back to this rail from some supply greater than 2V and present around this time. The dip 4ms later indicates there is a relationship with other domains, possibly supplied by VDIG1 or VDIG2.

Best Regards,

Rick S.

0 user3976270 over 6 years ago in reply to Richard Solarski

Prodigy 30 points

Hi,Richard,

Thank you for answering.

I will investigate the parasitic path from another power source.

Best Regards,

0 user3976270 over 6 years ago in reply to Richard Solarski

Prodigy 30 points

Hi.Richard

Cause of leakage
This is because the signal line using VAUX2 was pulled up with another 3.3V power supply.

If I continue to use VAUX2 with this waveform, is there any damage to the CPU (AM3354)?

Best Regards,

0 Richard Solarski over 6 years ago in reply to user3976270

TI__Genius 10885 points

From similar discussions on E2E, there may be too many variables to guarantee the AM335x will not be affected:

This quote from a related thread about the 1.8V supply sequence indicates that any sequencing outside of the recommendations could have unknown consequences:

"We are not aware of any issue caused by improper sequencing of the 1.8V supplies. However, there are many variables that may contribute to potential problems resulting from improper power sequencing. Therefore, it is not possible to guarantee a system will not have a problem if a product is not designed to follow the requirements/recommendations described in the note."

http://e2e.ti.com/support/processors/f/791/t/776564?tisearch=e2e-sitesearch&keymatch=am335*%25252525252525252520sequence%25252525252525252520vdds

Best Regards,

Rick S.

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TPS65910: TPS65910:About the output waveform of VAUX2