MP8030 EN pin voltage rating

Hi all, I have made a PCB for a 12V 36W solution by using MP8030 through PoE.

Problem facing:
DCDC convertor no response after plug the PoE cable.

The PoE section of MP8030 works normal. I pulled up the PG by 200K resistor through SRC and pull the EN up by another 200K resistor through PG.

Strange part:
The DMM show my MP8030 EN pin is 56V while powering by PoE. Yes the typical circuit in datasheet is pulling up the EN pin by SRC pin which is 57V in max. But the maximum rating of EN pin voltage should only 6.5V.
So What I thinking is that is I will get 6.5V on EN pin if it works fine. Even pulling up by 57V it will clamp by the internal clamping diode.

Does it mean my MP8030 IC is already burnt or something? What is the voltage level of EN pin when it’s in working condition?

Hi Ben,

Apologies for the delayed response.
Do you have a schematic you can share? Is this initial testing and bringing up board?
With internal zener, if EN is pulled above 6.5V, need to ensure the current is below 0.4mA.

Best Regards,

Hi Yu,

Thanks for the reply. Apology that the problem is solved and it’s faulty PCB layout.

The MP8030 QFN-32 layout pitch is not identical for every pin. The short edge pitch is 0.65mm. Where the long edge is 0.5mm.

The chip works fine for new PCB layout now thanks.:slight_smile: