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PoE+ PSE isolated supply

Other Parts Discussed in Thread: LM5020

Hello,

I am starting to design isolated power supply for Power over Ethernet injector. Frankly speaking, this is my first isolated converter design and I don't know if I'm heading in a good direction.

This should be:

18-60 V input, 56 V output. . Power 35W. And price should be as low as possible.

Industrial purpose.

I am considering using LM5020 controller (flyback) with external transistor. Working around 250 kHz. I am a bit afraid using higher frequency because it will be my first flyback converter. I wish also to use planar power transformer.

I would like to ask if I'm heading in good direction with my design. Maybe I should consider other controller, topology or frequency?

I would be really grateful for any suggestions, materials of similar designs or design tips.

The only reference design I have found is PMP4068, using UCC2809. There are a lot of designs of converters used as power device (48V -> 3.3 or similar) but i have troubles in finding reference designs for power source equipment converter.

Best regards,

Tomas

  • I am working on similar problem and am using the LM5020. 

    My specs are 20-70 V input, 24V output @ 3A.

    How is your progress? 

    One requirement I have for my project is that the circuit go into hiccup mode on persistent overcurrent condition. By hiccup mode, I mean that the output drops to zero, and the unit shuts down for a bit before restarting. I am using an auxiliary winding on my transformer to produce 12V for the circuit to run off, which shuts down the integrated linear regulator.  think I can accomplish hiccup mode by sizing capacitor on auxiliary winding and capacitor on softstart pin. 

    Do you have a similar requirement on hiccup mode. Have you tried hiccup mode overcurrent protection?