TPS23755: Issues with Seamless Switchover Using TPS23755 and TPS2121

Yaman Kurrey

Part Number: TPS23755
Other Parts Discussed in Thread: TPS2121,

Tool/software:

Dear Team,

We are utilizing the TPS23755 Power over Ethernet (PoE) Powered Device (PD) controller in conjunction with the TPS2121 for seamless power switchover between PoE and DC jack. However, we are encountering an issue where the switchover is not as seamless as expected. Specifically, we are observing a small delay during the switchover process, which is causing our system to reboot.

Are there any specific recommendations for optimizing the switchover time between PoE and DC jack?
Could there be any additional factors or components we should consider to minimize the delay?
Any insights or suggestions would be greatly appreciated.

over 1 year ago

0 Brandon Beader over 1 year ago

TI__Genius 15275 points

Hi Yaman,

Our PD Apps expert is currently out of office, please expect a slight delay in his response. Thanks for your patience!

Regards,

Brandon

0 Diang Xing over 1 year ago in reply to Brandon Beader

TI__Mastermind 37061 points

Hi Yaman,

Thanks for reaching out!

Could you share a pdf version schematic? The image resolution is too low to review. Thanks!

Besides, our TPS23755 evaluation board (https://www.ti.com/tool/TPS23755EVM-894) is hitless transition. It does not use the TPS2121, where D3 is used for oring and switching; D8 is used for oring.

Best regards,

Diang

0 Yaman Kurrey over 1 year ago in reply to Diang Xing

Prodigy 20 points

Hi Diang,

Thank you for your response.

The pdf version of schematic is attached below :-

1513.PoE_1.pdf

Regards,

Yaman

0 Diang Xing over 1 year ago in reply to Yaman Kurrey

TI__Mastermind 37061 points

Hi Yaman,

Thanks for your pdf file. I will get back to you next week.

Best regards,

Diang

0 Diang Xing over 1 year ago in reply to Diang Xing

TI__Mastermind 37061 points

Hi Yaman,

Thanks for your patience.

For the schematic I did not see an oring issue from TPS23755EVM side. The lose of seamless switchover could be caused by the TPS2121's bidirectional FETs could not response fast enough.

I would recommend you to post the E2E in the TPS2121 team. If you still want to double check original seamless switchover circuit in TPS23755EVM, you can DNP R308, U24, then mount D29 and short 12V_ADAPTER and 12V_POE.

Best regards,

Diang

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TPS23755: Issues with Seamless Switchover Using TPS23755 and TPS2121