TPS25751: External Mosfet version turns off sourcing after a few seconds

Darren DeBattista1

Part Number: TPS25751
Other Parts Discussed in Thread: BQ25731, PMP41013

Tool/software:

Hi,

I am using the TPS25751 for a 4S battery powered USB-PD application. At first, I was using the TPS25751D (internal MOSFET) version and everything worked fine, both source and sink. Due to supply shortages, we had to redesign using the TPS25751S (external MOSFET) version. We kept the schematic exactly the same, but added the two external MOSFETs as needed. While sink is working correctly, sourcing is not. When I try to charge some smartphones, some will start charging and than cut the charging current to zero after a few seconds. This was not happening with the TPS25751D. I have attached the json file I am using together with two short videos, one showing the smartphone charging on the TPS25751D (no issues) and the other showing the same smartphone charging using the TPS25751S where the issue is happening. What can cause such an issue? Is it something in the TPS25751S chip? (maybe INDPM setting is not being correctly set in the TPS25751S memory?)

Note: As you can see in the videos, I am using a USB-PD analyser. If I turn off the PD coms in the analyser, the smartphones enter PPS mode and this always works fine, as I see the source voltage smoothly rising up until its settles and current keeps flowing. The issue is when it smartphone directly negotiates 9V. Also, the TPS25751 keeps on trying to apply charge until at one point it manages and works.

As a side note the following are the smartphones tried (note that all had no issues when using the TPS25751D)

Samsung Galaxy A23: negotiates 9V, current immediately reaches about 1.5A, than drops to zero after few seconds.

Xiaomi Redmi note 9 pro: Same as the Samsung

Google Pixel 7: worked without issues.

Vids and JSON.zip

22 days ago

0 Raymond Lin 22 days ago

TI__Mastermind 28496 points

Hi Darren,

Are you also able to provide schematic or block diagram of your hardware for both the 'D' and 'S' version of TPS25751?

Thanks and Regards,
Raymond Lin

0 Darren DeBattista1 19 days ago in reply to Raymond Lin

Intellectual 465 points

Hi Raymond,

Find attached what requested.

TPS25751S.pdf TPS25751D.pdf

0 Raymond Lin 18 days ago in reply to Darren DeBattista1

TI__Mastermind 28496 points

HI Darren,

I'll review the schematic and get back to you. What kind of DCDC/BQ are you pairing with TPS25751?

Thanks and Regards,

Raymond Lin

0 Darren DeBattista1 18 days ago in reply to Raymond Lin

Intellectual 465 points

I'm using the BQ25731 following the PMP41013 reference design.

0 Raymond Lin 17 days ago in reply to Darren DeBattista1

TI__Mastermind 28496 points

Are you able to capture PD logs and see what PDO each phone is requesting?

Also as a side note accoring to PD spec the minimum voltage for source PPS is now 5V, 3.3V is not supported on TPS25751.

0 Darren DeBattista1 16 days ago in reply to Raymond Lin

Intellectual 465 points

Hi,

I updated the json file to limit the PPS minimum voltage to 5V. I tried this new file but I still have the same issue.

I tried to see which PDO the smartphone is requesting but cannot really tell. From the testing module, I am assuming that the phone is requesting the 9V PDO as the voltage is being set to 9V.

0 Raymond Lin 12 days ago in reply to Darren DeBattista1

TI__Mastermind 28496 points

Hi Darren,

Can you check and read back the following registers so we can see if a fault has occurred? Also if possible, a PD log would help us understand further why the disconnection keeps occurring (i.e. if one side is sending hard reset or current is being overdrawn, etc.)

Thanks and Regards,

Raymond Lin

0 Darren DeBattista1 8 days ago in reply to Raymond Lin

Intellectual 465 points

Hi,

I tried to read these registers but the data I'm receiving is all 0xFF. I know the connection is correct cause the TPS25751S is returning the correct number of bytes as part of the reply. Moreover, there is a clock stretching of around 7ms.

Am I doing something wrong when trying to read from the TPS? Is there a special command we need to send first?

Note: I tried the same on a TPS25751D but had the same 0xFF replies.

0 Raymond Lin 2 days ago in reply to Darren DeBattista1

TI__Mastermind 28496 points

Hi Darren,

What is the full register read from Power Path Status and PD Status register? Can you capture Saleae scope capture when reading these registers? Is TPS25751 in APP mode when reading the status register (MODE register 0x03)?

In addition do you have scope capture of VBUS, PPHV and PP5V during the sourcing issue?

Thanks and Regards,

Raymond Lin

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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TPS25751: External Mosfet version turns off sourcing after a few seconds