MP8020 Detect Phase and Class Negotiation

Hi Team,

I’m working on a custom board using MP8020 and I’ve some doubts.

I’m checking with the oscilloscope the PoE negotiation part and as I’ve seen and attached here, the PSE (25W) generates the Detection part sourcing voltage between 2.7V and 10V, about 7V in my case, but the MP8020 does not continue with the negotitation class part (14.5V-20V).

I’ve measure between VDD an GND but I can’t see the 25K of RDET. As datasheet shows a N-MOS enable or disable RDET. As it never appends, the controller part doesn’t work as I spect.

Which are the needs for the MP8020 to close that MOS in the Control Logic part? Because voltage reach the IC and that part should be supply.

What could be the reason why it doesn’t work?

I’ll be waiting your news asap.

Best regards.