The PoE Power Regulator 28V is an add-on board for our Ethernet Shield and EtherTen that allows them to accept up to 28V supplied via the Ethernet cable as a "Powered Device" (PD) on a home-brew Power-over-Ethernet network. It is also a very useful general purpose 5V or 7V output 1A switchmode supply for projects.

Note: This regulator is not compatible with commercial 48V Power-over-Ethernet systems implementing the 802.3af/at standards. It should only be used with PoE systems that deliver less than 28Vdc. Further background information on Power-over-Ethernet schemes can be found at For commercial PoE systems we have an alternative module called the Power-over-Ethernet Regulator 802.3af.

Installation on Ethernet Shield or EtherTen

1. Remove the jumpers from the PoE header on your Freetronics Ethernet Shield or EtherTen if they are fitted.

2. Place the provided single-pin headers into the GND and 5V rails adjacent to the prototyping area on the Ethernet Shield, or into the special holes provided on the EtherTen.

3. Place the Power Regulator 28V onto the header pins. If fitting to an EtherTen we recommend use of a small piece of cardboard or similar as a spacer to hold the module above the other parts on the board until it has been soldered in place.

4. Solder the header pins to the top of the Power Regulator 28V. Trim off any excess length.

5. Turn over the Ethernet Shield or EtherTen and solder the bottom of the single-pin headers in place. Trim off excess length.

6. Connect your Ethernet Shield or EtherTen to your network.

7. Supply up to 28Vdc to the network segment using Power Sourcing Equipment such as the Freetronics 4-Channel PoE Midspan Injector.

Note: An alternative installation technique is to solder a 4-pin female header to the underside of the Power Regulator 28V, allowing it to be removed from the host board at any time if required. However, this will cause it to sit higher above the board.

Use Stand-Alone or with a Breadboard

The PR28V can also be used as a handy general-purpose voltage regulator in many of the same situations that you would use a simple linear regulator such as an LM7805. The PR28V can accept up to 28V input while providing a regulated 7Vdc or 5Vdc output for your project.

Connect your 9-28Vdc input to the inner pair of pins as marked on the PCB, and use the outer pair of pins as the GND and VCC connections to your project. Make sure you configure the PR28V for 5Vdc output as described below if you will be directly driving a 5V circuit.

Selecting 5V / 7V Output Mode

The PR28V is designed to provide 7Vdc output by default, which is then fed to the onboard voltage regulator of your Arduino for final conversion to 5V. However, the PR28V can be configured to directly provide a regulated 5Vdc output by bridging across the solder jumper provided on the bottom of the PCB. This is ideal if you want to use it as a stand-alone voltage regulator directly delivering 5Vdc to your project.

With the pads separated (default) the output voltage is set to 7Vdc. If you bridge across the pads the output is set to 5Vdc.