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TPS2373-4EVM-758: one question about TPS2373-4EVM

Oliver Ou
Intellectual 2845 points
Part Number: TPS2373-4EVM-758
Other Parts Discussed in Thread: TPS2373, PMP20859

 Hi,

Customer has some questions about the oring application on  TPS2373-4VM:

1. On TPS2373-4EVM-758,  if the pass FET is turned off by APD pin, Adapter would power the system.

The DCDC output would break off, when switching from adapter to PSE. Is it right?

2.  The PSE side still keeps connecting since MPS function in TPS2373 would turn on, is it true?  

Datasheet shows the MPS would work if APD is higher than 1.65V.

 3. If item2 is true, why it can’t switch back from adapter to PSE to achieve smoothly switch between adapter and PSE ?

Can you give some comments about the oring application?

Thanks.

 

  • 0
    TI__Expert 3700 points
    Hi,

    Thank you for your question. Our team is currently out of the office celebrating the US holiday of Memorial Day and plan to be back in the office on Tuesday, 5/28. We will respond as soon as possible. Thank you for considering Texas Instruments PoE products.

    Best Regards,
    Brett
  • 0
    TI__Mastermind 40100 points
    Hi Oliver,

    1. As the EVM is designed, yes it would NOT have smooth transition between PoE and adapter.
    2. Auto MPS will work and PSE will remain connected. The pass will be OFF and adapter will be powering the DCDC.
    3. I recommend looking at the training video below. It's the same concept with a adapter and PoE as it is with two PoE inputs. It has to do with the inrush current when transitioning between adapter voltage and poe voltage.
    training.ti.com/designing-dual-input-poe-pd-systems-power-redundancy-smooth-transition-and-power-sharing

    For a smooth transition solution, I recommend using PMP20859 as this have smooth transition between 2 poe inputs and primary side adapter. If only one poe input is required, you can always remove one PoE channel of PMP20859 and then you have design that can do smooth transition between adapter and PoE. Thanks!