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TPS23753: POE & DC JACK Power ORING || 12V ADAPTER DC JACK PRIORITY

Hemal Patel
Intellectual 345 points
Part Number: TPS23753
Other Parts Discussed in Thread: TPS23731, PMP22477

we have requirement of 12Volt [12W to 15W] POE Supply. 

We are providing both POE and DC Supply [12V DC Adapter] as a input supply source and for that we need to give priority to 12V DC Adapter in case of both POE and DC Supply available.

Requirement:- So suppose if a device is running on POE Supply and in this condition 12V Adapter DC supply entered then according to DC Supply as a priority, supply need to switch power from POE  to DC Adapter and switching must be seamlessly so that device able to switch smoothly without Reboot. And now further by taking this scenario continue suppose DC Adapter Power supply removed [POE supply still plugged in] then device supply again get back to POE as input source smoothly without Reboot.

We have referred below documents For adapter or’ing solutions  

https://www.ti.com/lit/an/slva306a/slva306a.pdf

in this we have checked Option 2 [Adapter Preference and APD] & Option 3 [Adapter Priority & DEN Pin to Disable the PoE MOSFET] solution but in both solution as our understanding device going to reboot while switching so kindly confirm that our understanding is right and suggest what additional circuit need to add to avoid reboot while switching.

Please support us and provide ref. design to set Adapter priority without reboot.

  • 0
    Intellectual 345 points

    Block Diagram of Option 2 [Adapter Preference and APD] 

    Block Diagram of  Option 3 [Adapter Priority & DEN Pin to Disable the PoE MOSFET] 

  • 0 in reply to Hemal Patel
    TI__Mastermind 37121 points

    Hi Hemal,

    Thanks for reaching out!

    We will get back to you by Feb/23.

    Best regards,

    Diang

  • 0 in reply to Diang Xing
    TI__Mastermind 37121 points

    Hi Hemal,

    Thanks for your patience.

    Looks that you want seamless transition for both AUX->PoE and PoE->AUX cases. Meanwhile, the AUX priority should be higher than PoE.

    I would recommend you to use TPS23731 if your target is Class-3 considering TPS23731 has auto maintain power signature function.

    You can considering using TPS23731's reference circuit (PMP22806) + PMP22477’s secondary oring circuit (PMP22477). It will lower the PoE output voltage when 12-V adapter is added. Please see the heighted circuit in below.

    I saw you also asked a similar question so I will close this thread for now and keep communication with you in another thread.

    Best regards,

    Diang