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TPS23730EVM-093: Poe Magnetic and ESD, EMI and Overcurrent protection in Poe PD

Part Number: TPS23730EVM-093
Other Parts Discussed in Thread: TIDA-01411, TPS23730

Dear *,

1) i read that the CMC in Poe magnetic is recommended on cable side but in TPS23730EVM-093 magnetic used have CMC  with three-wires on phy side.

1a) Why do you use PoE magnetic with CMC in PHY side?

1b) Is there a benefit to use three-wire CMC instead of standard two wire CMC?

1c) Can we use Poe Magnetic with CMC (like VP6014 HF) on cable side?

2) ESD Protection recommendation  between Poe magnetic and Diode bridge? (slua469, slua736 and TIDA-01411)

2a) The MOV are required for lightning surge protection only is that correct ? What test or standard describes the requirement of MOV?

2b) i can't find in the mentioned docs above following : Bidirectinoal TVS1 and TVS2 between 

Are these TVS required for ESD protection?

Also  what is better to use here a TVS eg 5.0DMDJ58CA or an SIDACtor thyristor eg P0640SDLRP ?

Protecting PoE Equipment from Overvoltage

2c) in slua736 there ia TVS from VSS to RTN used while in TPS23730EVM-093 there is only a shottkey diode B3100-13-F from VSS to RTN why?

3) Over current protection on PD side

3a) i don't see any fuse protection on PD side , is this not needed?

3b) if we like to add fuse, where is the recommended place to put a fuse 

- before diode bridge on all for wires ( need 4 0603 chi fuses)

- after diode bridge ? and then before or after CMC filter on VDD ?


do you recommend , chip fuse, resettable fuse, efuse or DTCS TCS-DL004-250-WH

does TI has a recommended efuse for Poe?

Best Regards,


  • Hello,

    1. You can use any PHY you want to. We chose this to match previous designs. 

    2.  The papers and designs you mentioned are for lighting surge considerations. This EVM is meant to display the capabilities of the TPS23730 IC. We do not contest that this EVM is the compete design that follows all lighting surge applications. However, if your application requires these protections, please follow the guidelines in those papers. 

    It is difficult to say, "MOVs are required." - surge protection is based on the design, the layout, the common mode caps, the grounding, the cabling, etc. It also depends on what level of surge you are trying to protect against. Based on our designs for our testing, they are required for 6-kV surge. 

    For the b-directional TVS on the data lines, there is one SPD per data line in slua736 

    We recommend 5.0DMDJ58CA. 

    3. The TPS23730 has over current protection. Consider figure 8 in the user's guide - this is when the output is shorted and load current would be "infinity." the device enters a hiccup mode. 

    I suggest ordering an EVM and taking the load current up until you see this behavior. 

    Additionally, our PSE's have a current foldback feature so that they do not provide more power than they are able. 

    We designed multiple current protections so we do not have a recommendation for a fuse or where to put it. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.




    Michael P.

    Applications Engineer

    Texas Instruments