TPS25730: TPS25730 passing on the lower voltage than the set voltages. How?

Deep Raj Khadka

Part Number: TPS25730

Tool/software:

The controller is configured to accept input voltage between 9V and 20V. (ADC1 and 2 are configured for 9 and 20V)
When I connect 5V (from USBA) connector I see 5V on the PPHV, which I was not expecting when input voltage(5V) is below the lower limit voltage(9V).
So, there is no power negotiation and still 5V goes through VBUS to PPHV. Can you help to explain this situation?

1 month ago

0 Aya Khedr 1 month ago

TI__Mastermind 24582 points

Hi Deep,

Thank you for reaching out!

1- Are you testing with a TPS25730 EVM or a custom board?

2- What are the ADCIN3&4 settings?

Best Regards,

Aya Khedr

0 Deep Raj Khadka 1 month ago in reply to Aya Khedr

Prodigy 30 points

Hi Aya,

1. We are using TPS on a custom design.

2. ADCIN3and4 are configured for 3A (operating and maximum both at 3A)

(a side question => was curious what is the difference if for example operating current is set at 0.5A and max at 3A vs setting both at 3A)

0 Aya Khedr 1 month ago in reply to Deep Raj Khadka

TI__Mastermind 24582 points

Hi Deep,

Thank you for the additional information. TI is on Holiday today. I will look into this and get back to you by Wednesday.

Best Regards,

Aya Khedr

0 Deep Raj Khadka 28 days ago in reply to Aya Khedr

Prodigy 30 points

In the datasheet, the measurement example also shows that the 5V is enabled at the output for a short time before the negotiated (20V). Can you also help to explain this behavior in addition to the question above? Thanks

0 Aya Khedr 25 days ago in reply to Deep Raj Khadka

TI__Mastermind 24582 points

Hi Deep,

I will provide a detailed explanation for the observed behavior by end of day.

Best Regards,

Aya Khedr

0 Deep Raj Khadka 17 days ago in reply to Aya Khedr

Prodigy 30 points

Hi Aya,
Any updates on this .

0 Aya Khedr 16 days ago in reply to Deep Raj Khadka

TI__Mastermind 24582 points

Hi Deep,

Apologies for the delay. I need some additional time to look into this and will get back to you this week.

What is the desired behavior that you’re looking for when plugging in a USB-A to USB-C cable?

Best Regards,

Aya Khedr

0 Deep Raj Khadka 15 days ago in reply to Aya Khedr

Prodigy 30 points

When plugging USB-A power supply (that only has 5V and no PD negotiation), I was expecting 0V (because the accepted range is set to 9-20V input)
Also would be nice to get answer to other questions about operating and maximum current above)

0 Aya Khedr 14 days ago in reply to Deep Raj Khadka

TI__Mastermind 24582 points

Hi Deep,

The TPS25730 asserts its capability mismatch bit in the PD request message when the negotiated voltage is lower than the minimum required power but does not automatically disable the sink path. The minimum required power is the minimum voltage * operating current (9*3 = 27A for example in your case).

The maximum voltage and maximum current determine the maximum allowed power.

I will check internally if there is a way to disable the sink path upon capability mismatch and get back to you.

Best Regards,

Aya Khedr

0 Deep Raj Khadka 7 days ago in reply to Aya Khedr

Prodigy 30 points

Thanks for the explanation. Please let us know if there is a way to disable the sink path when there is capability mismatch.

0 Aya Khedr 2 days ago in reply to Deep Raj Khadka

TI__Mastermind 24582 points

Hi Deep,

I am checking with the team and will get back to you by end of week the latest.

Best Regards,

Aya Khedr

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TPS25730: TPS25730 passing on the lower voltage than the set voltages. How?