TPS65987DDK: Unable to swap power role to source when connecting battery

Jacob Cayetano

Part Number: TPS65987DDK
Other Parts Discussed in Thread: TPS65987

Our board uses the TPS65987DDH to negotiate a USB-C power/data connection between a tablet and the board. The board is powered by a battery when the battery is inserted (source), but is powered by the tablet via VBUS when the battery is disconnected (sink). The tablet should be charged by the board when the battery is connected.

When disconnecting the battery with the tablet still connected, the board successfully swaps to a sink and lets the tablet provide 5V power over VBUS. However, we are unable to swap back to the source power role when reconnecting the battery. VBUS power is still provided by the tablet even though PP_HV2 on the TPS65987DDH is now available to source power to VBUS again. However, if we unplug and replug the USB-C connection to the tablet while in this state, it appears to renegotiate the connection and properly source VBUS from the board and charge the tablet again. We do not want to have to unplug and replug the USB-C connection for this use case and would ideally just be able to disconnect and reconnect the battery.

Our configuration file is set for preferring power source: Cayetano_TPS65987_Firmware_PowerSwap.pjt

We have tried various configurations with the configuration tool without success. We are also observing this behavior on the TPS65987EVM board.

What could be the cause of this issue?

Thanks for any help you can give.

over 1 year ago

0 Kevin Kosta over 1 year ago

TI__Genius 17985 points

Hi,

Thanks for reaching out on E2E!

I will take a look and respond to this thread tomorrow.

Thank you,

Kevin

0 Jacob Cayetano over 1 year ago in reply to Kevin Kosta

Prodigy 70 points

Hello Kevin, thanks for your response.

I've been searching the forum and I came across this thread: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1292764/tps65987d-data-role-changing-during-power-role-swap?pifragment-323297=2#5077980

In this thread, the TI app engineer appears to modify the firmware to adjust some "non-user configurable" settings. I grabbed the project "david_comp-mode-all.pjt" and modified it for our use case and I am now able to reconnect the battery and have power mode swap correctly.

david_comp-mode-all_modded.pjt

While this does "solve" my issue, I would like to know how this project file is different from the base firmware available to us and how this can be made replicable for users. I would prefer that the source of our solution not be sourced from a single forum post, but rather have a build procedure that we can use to create it if the need arises.

Thanks,

Jacob Cayetano

0 Kevin Kosta over 1 year ago in reply to Jacob Cayetano

TI__Genius 17985 points

Hi Jacob,

Glad to hear its resolved!

I will let you know what the differences are as soon as I get the chance.

Thank you,

Kevin

0 Conner Gillette over 1 year ago in reply to Jacob Cayetano

TI__Genius 13880 points

There is a reverse current protection setting in the configuration file (.pjt file) that modifies a non-user configurable register. The base firmware itself is not changed.

Kind regards,

Conner Gillette

0 Jacob Cayetano over 1 year ago in reply to Conner Gillette

Prodigy 70 points

Hello Conner, thanks for the response.

Is there no way for us to be able to build that file ourselves? Having a one-off file is precarious from a source control standpoint and also makes it difficult to troubleshoot or trace in the future.

Thanks,

Jacob Cayetano

0 Kevin Kosta over 1 year ago in reply to Jacob Cayetano

TI__Genius 17985 points

Hi Jacob,

I understand the concern but we cannot expose these registers as changing them can have huge risk and cause damage to the PD if used improperly.

Thank you,

Kevin

0 Jacob Cayetano over 1 year ago in reply to Kevin Kosta

Prodigy 70 points

Hello Kevin,

That makes sense and I appreciate the response. I must do my due diligence for my team by recommending that TI include the modified firmware in the TPS96598x Application installation so that users that have run into this issue have a standardized option. I understand if that may be a big ask coming from someone external to TI, but it appears that this fix has helped multiple users already so it seems significant enough to include.

Thanks,

Jacob Cayetano

+1 Kevin Kosta over 1 year ago in reply to Jacob Cayetano

TI__Genius 17985 points

Hi Jacob,

Understood!

I will work with the team to see the feasibility of including this in future releases!

Thank you,

Kevin

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TPS65987DDK: Unable to swap power role to source when connecting battery