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PSE compatibility with TPS2379

Gaayathri Nagarajan
Intellectual 270 points
Other Parts Discussed in Thread: TPS2379, TPS2379EVM-106, LM3409HV

Hi Team,

Are the below AC powered single port POE midspan injectors compatible with PD controller TPS2379?

6813.POE29U-1AT_30W.pdf

POE31U-1AT_30W.pdf

If so, which can be preferred?

Or what is the difference between them as their datasheets prove to be almost the same.

  • 0
    TI__Genius 15685 points

    Hi Gaayathri,

    From the datasheets, these two PSE injectors look the same except the temperature spec. As long as the PSE injector is IEEE 802.3at compliant, it should be working well with TPS2379. I think both PSE injectors should be OK. 

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    Intellectual 270 points
    Hi Penny,

    Thanks for the response.

    I am planning to use the PD evaluation board TPS2379EVM-106 with PSE POE-31U-1AT.

    The PSE POE-31U-1AT delivers 30W.
    Considering the cable losses, the power delivered to the PD TPS2379 will be 25.5W.

    Can you please clarify on the below queries?

    1. Will TPS2379EVM-106 be driven by power lesser than or equal to 25.5W coming from PSE POE-31U-1AT?
    2. What topology does the data and power transmission follow when used with POE-31U-1AT delivering 30W? (i.e.) are the data & power transmitted through same pair of cables or different pairs of cables?
    3. For TPS2379EVM-106 , what can be the suitable DC-DC converter topologies to be used?

    Thanks in advance.

    Regards,
    Gaayathri.N
  • 0 in reply to Gaayathri Nagarajan
    TI__Genius 15685 points
    Hi Gaayathri,

    Please see the comments below:
    1. Will TPS2379EVM-106 be driven by power lesser than or equal to 25.5W coming from PSE POE-31U-1AT?
    Yes. TPS2379EVM-106 can do that. TPS2379 can work with any IEEE compliant PSE devices.
    2. What topology does the data and power transmission follow when used with POE-31U-1AT delivering 30W? (i.e.) are the data & power transmitted through same pair of cables or different pairs of cables?
    It really depends on the design of the POE-31U-1AT meaning which wiring method does POE-31U-1AT pick. From PD point of view, it doesn't care the power comes from which pairs.
    3. For TPS2379EVM-106 , what can be the suitable DC-DC converter topologies to be used?
    We have a reference design of TPS2379 with DCDC converter(active clamp forward, current booster circuit added)http://www.ti.com/tool/PMP8923. Do know what's the output voltage? Usually we see flyback when the output voltage is higher than 12V, and active clamp forward when output voltage is lower 12V.

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    Intellectual 270 points
    Hi Penny,

    Thanks for the response.

    TPS2379EVM-106 gives an output DC voltage of 37-57 V. Can you please let me know if this can be used to drive the LED Driver IC MP24833 – (3A, 55V) safely?

    Regards,
    Gaayathri.N
  • 0 in reply to Gaayathri Nagarajan
    TI__Genius 15685 points

    Hi Gaayathri，

    The PD's output voltage really depends on the output voltage of the PSE. I noted that the Phihong's PSEs you mentioned above have 56V output. The recommended maximum operating voltage of MP24833 is 55V. If the cable is not very long, there could be some problems from the MPS part. TI has a wide input range LED driver LM3409HV and we have seen customers using TPS2379+LM3409HV.

    How much power do you need in the system? The LED driver can support 165W, but the Phihong PSE only can output 30W. 

    Best regardsm

    Penny

  • 0 in reply to Penny Xu
    Intellectual 270 points
    Hi Penny,

    Thank you.

    The LED load to be driven will be around 25 W and I am planning to operate TPS2379EVM for 25.5 W. Is there any possibility of adding a protection feature with MP24833 to limit the overvoltage, such that it does not exceed 55 V?

    Regards,
    Gaayathri.N
  • 0 in reply to Gaayathri Nagarajan
    Intellectual 270 points
    Hi Penny,

    Continuation of my previous post,

    1. In LED driver IC MP24833 , there is overvoltage protection feature pertaining to pin OVP. Will that not help us?

    2. And, how else to limit the input voltage to < 55V for MP24833?

    Regards,
    Gaayathri.N
  • 0 in reply to Gaayathri Nagarajan
    TI__Genius 15685 points

    Hi Gaayathri,

    We recommend LM3409HV which has wide input range from 6V to 75V. If you want to use MPS part with max 55V input limit, it's better to check with MPS engineers to see if 56V input could cause any problems and possible solutions. Thanks.

    Best regards,

    Penny