The new board will also eases a supply problem. “Unfortunately, the first-gen PoE HAT uses silicon that’s in short supply,” according to Raspberry Pi. “The old HAT will remain in production, but we are taking the unusual step of announcing this new product before we have stock in channel so that industrial customers can consider migrating to the new PoE+ HAT, which will have shorter lead times.”
Raspberry Pis from 3B+ onward have an Ethernet jack with tapped windings connected to a 4pin header through which a PoE board can extract power. The add-on board picks up this header and produces 5V to power the Pi and its peripherals from the 37-57Vdc carried by the Ethernet cable through rectifiers and an isolated regulator.
The original PoE HAT implements 802.3af and can deliver 13W. By complying with 802.3at, the plus version can deliver up to 25W.
|PoE HAT||PoE+ HAT|
|Supported standards||802.3af||802.3af, 802.3at|
|at up to||2.5A||5A|
|PCB||4 layers, 2oz copper||4 layers, 2oz copper|
|Compatible with||Raspberry Pi 3B+, 4B||Raspberry Pi 3B+, 4B|
The 2.2 CFM fan (photo) is included to cool the Pi processor
Operation is over 0 to +50°C.
Changes from the original include a move to active rectification (Microchip PD70224ILQ mosfet bridge chip) to remove power dissipation due to diode drops, and a planar transformer, supplied by Bourns, which is lower profile than the earlier version (height is dominated by the fan).
Raspberry Pi PoE+ HAT will be available in early June.