Supporting 802.3af and 24v Passive PoE with MP8007

DC-DC Power Converters
1

I am designing a board with the MP8007 to support standard 802.3af as well as non-standard 24v passive (always on) PoE using the buck topology described in the datasheet (fig.16 p.26) with 5v out.

I assume the IC won’t take kindly to being force fed 24v without the standard negotiation, so I am planning on using the 24v passive PoE supply as the AUX power supply to the IC to allow the downstream DCDC converter to work as normal, and use a dip switch to disconnect Ethernet pins 7,8 from the IC VSS and connect them to the adaptor GND rail.

Is it reasonable to expect this to work as described?

2

Hello,

If you are using a 24V supply instead of PSE input, you can use the AUX pin.
Please follow the application section on page20 in the datasheet. You can also refer to figure14.

Best Regards,
Yu