LM5072 used in AUX mode causing network shutdown

James Autry77

Other Parts Discussed in Thread: LM5072

I am using an LM5072 with an AUX mode available. In our situation, we can have a POE input while still being used in AUX mode with an external supply. It appears that when the RAUX is active, it supposedly disqualifies the POE class sense which shuts down the POE. Unfortunately, on some POE switches, this appears to also shutdown the network link. Is there a way to shutdown the LM5072 switcher without the input POE being shut down?

over 10 years ago

0 Darwin Fernandez over 10 years ago

TI__Mastermind 41800 points

Hi James,

By network link shutdown, do you mean, that when an aux input is connected and powering the load (so PSE is not providing power to the PD but the RJ45 ports are connected with an Ethernet cable ), data canNOT be sent or received?

0 James Autry77 over 10 years ago in reply to Darwin Fernandez

Prodigy 30 points

That is correct, the cisco switch shuts down the link. If I remove the RAUX signal from the LM5072, it comes back.

0 James Autry77 over 10 years ago in reply to Darwin Fernandez

Prodigy 30 points

I am thinking that if Rt timing resistor input is used to sync, perhaps it could be used to shutdown the oscillator.

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LM5072 used in AUX mode causing network shutdown