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TPS2375: Rj45 (7499210124A) and LM2592HV

nta_xyz
Prodigy 55 points
Part Number: TPS2375
Other Parts Discussed in Thread: LM2592HV

Hi

I have used 7499210124A as a RJ45 connector and I need to convert the POE voltage to 3.3 volt, so I have some questions:

1- Is it necessary to use TPS2375 or can I connect the POE voltage directly to the LM2592HV?

2- can I connect the 7499210124A RJ45 connector directly to the TPS2375 or I should use DF01S? (there is bridge rectifires in the selected RJ45)

3- is it possible to connect the TPS2375 output voltage to LM2592HV for converting POE voltage to 3.3 volt?  

Thank you in advance for guiding me

 

  • 0
    TI__Mastermind 40670 points
    Hi Nima,

    1. A compliant IEEE802.3 PSE must detect a compliant IEEE802.3 PD to turn ON. This requires a PD controller (like the TPS2375) on the PD front end design.
    2. A compliant IEEE802.3 PD just accommodate the different ways a PSE can send its voltage through the CAT5e cable. As such, the rectifying bridge is necessary.
    3. Yes this PWM controller can be paired with TPS2375 to buck down to 3.3V.
  • 0 in reply to Darwin Fernandez
    Prodigy 55 points

    Hi Darwin,

    Thank you for your good answers.

    about the question number 2, there is a rectifying bridge in the selected RJ45 (7499210124A) so is it enough or I should use DF01S too?  

    this is the 7499210124A RJ45 schematic:

  • 0 in reply to nta_xyz
    TI__Mastermind 40670 points
    Hi Nima,

    Ah yes I didn't notice the integrated diode bridge. If using this then you wouldn't need an external diode bridge. However, looking at this schematic, it does not have the bob smith termination (needed for balancing). It also does not allow to connect them on the two pairs externally. For this reason, I would not recommend using this component. If a magjack is desired, I recommend using one (or similar) that we've used in our evm like shown in the below link. The below magjack as the bob smith terminations but not the diode bridge. Thanks!

    www.ti.com/.../slvu315a.pdf
  • 0 in reply to Darwin Fernandez
    Prodigy 55 points
    Hi Darwin,


    Thanks for your kind answer.

    I have checked the RJ45 connector (MJFR0429) that you recommended, but I need a connector with LEDs, I can not find a RJ45 connector with these specefications:


    . POE 300mA

    . with integrated LEDs

    . with bob smith termination


    So do you know a connector with these features?


    Thank you again for helping me.
  • 0 in reply to nta_xyz
    TI__Mastermind 40670 points
    Hi Nima,

    Yes please see below link. Thanks!
    www.digikey.com/.../4725722

    Regards,
    Darwin