PoE Power for Raspberry Pi 3 model B+

PoE Power for Raspberry Pi 3 model B+

Raspberry Pi 3 B+

The new Raspberry Pi 3 model B+ design has made it even easier to add PoE hat, without the need for extra cables. The GPIO connector will provide all the connection required for PoE. Silvertel, a UK manufacturer of POE, telecom and power modules, have released a circuit and PCB layout for a 5V PoE adapter board ideal for the new Raspberry Pi 3 model B+ design. This PoE hat design uses the Raspberry Pi 3 B board’s GPIO connector to access the Ethernet transformer and power lines to provide a simple neat PoE solution. The information provided is available for free download and use by any manufacturer of accessories or general hobbyists. The information pack provided includes: a full bill of materials (parts readily available from on-line electronic component suppliers), a circuit schematic and the PCB layout. The Ag9905M is the smallest 12W PoE solution available at this time but Silvertel is constantly surprising the market.

Raspberry Pi 3 B+ 2                                      Raspberry Pi 3 B+ 3

The latest Release downloads including PHY protection can be found below. Released April 2018.

Download Circuit diagrams for PoE Adapter Board

Download PCB silkscreen (Top) for PoE Adapter Board

Download PCB silkscreen (Bottom) for PoE Adapter Board

Download example BOM

Download Gerber files for PCB

The winners of the Wales Technology Awards 2018

Over the last three years, the company has experienced dramatic growth in every overseas operating territory including China, USA, Australia, Italy, Russia and Japan.
The company’s strengths in technological innovation have seen it become the only company in the UK designing its particular product range of Power over Ethernet (POE) modules, and it is seen as one of the leading developers in the world for this type of product. A focus on miniaturization has also seen Silvertel create the world’s smallest POE module, which are perfect for the latest generation of Internet of Things products.

IEEE 802.3bt – The New 4 pair Standard of PoE Current Standards

IEEE 802.3bt – The New 4 pair Standard of PoE

Current Standards

Since its first release, in 2003, it became obvious that PoE provided great benefits however some applications were restricted by the power available. The first specification, called IEEE802.3af, allowed up to 12.95W at the Powered Device (PD) and the second, released in 2009 and called IEEE802.3at, allowed up to 25.5W. This allowed for 100m of cable between the Power Sourcing Equipment (PSE) and the PD. The power could be supplied on the spare pair or the data pair which was referred to as Mode A or B.

Standard Power from PSE
Power a
Cable Type Mode
802.3af 15.4 12.95 Cat 3 or 5 A or B
802.3at 30 25.5 Cat 5 A or B

It is important to note that the standards are backward compatible i.e. an 802.3af PD can be used with an 802.3at PSE and an 802.3at PD can be used with an 802.3af PSE but with the power limited by what the PSE can supply.

PoE can also be defined by the Type where a Type 1 is an IEEE802.3af device and Type 2 is IEEE802.3at device. Within each type there are various classes that the PD presents to the PSE which defines the minimum power delivered to the PD and would allow the PSE to manage its power available.

PoEType Class Current(mA) PD per Pair (W) PSE Power Per Pair (W)
1 0 0 - 4 0.44 - 12.94 15.4
1 1 9 - 12 0.44 - 3.84  4
1 2 17 - 20 3.84 - 6.49 7
1 3 26 - 30 6.49 - 12.95 15.4
2 4 36 - 44 12.95 - 25.50 30

What 802.3bt brings

More Power - This new standard allows the transfer of at least 71W to the PD with the maximum cable length. This extra power is delivered across all four pairs which minimizes the losses in the cable. This extra power available allows more applications at higher power like smart LED lighting, Cameras with AI and larger digital displays. However with this higher power and faster data speeds, cable quality and electronic design now becomes an important factor when trying to achieve maximum power and error free data transmission.

Connected Devices -The new standard allows for this higher total power to be split across two separate PD devices from a single IEEE802.3bt PSE output. The PSE will check both pair sets to see if it’s connected to single or dual signature PD. A single signature PD connection will operate as you would expect, monitoring the overall power consumption and imbalance between pair sets. A dual signature connection allows the designer to have two individual PD devices within their system, monitored by a single IEEE802.3bt PSE, thus giving them the opportunity for 2 independent rails within their system whilst only using a single Cat5e cable. The independent monitoring on each pair set also allows for power saving in the end users device where one of the rails may choose to go into standby mode whilst the other rail may need to continue to operate at full power.

New classes and types - The increase of power is not implemented in one step the standard brings 2 new PoE types and 4 new classes for effective power management.

PoEType Class Current(mA) PD per Pair (W) PSE Power Per Pair (W)
3 4 0 - 4 12.95 - 25.5 30
3 5 9 - 12 40 45
3 6 17 - 20 51 60
4 7 26 - 30 62 75
4 8 36 - 44 71 90

Lower standby power –After powering the port the PSE monitors the current drawn is above a set limit, known as the Maintain Power Signature (MPS), to detect if the PD has been disconnected. The IEEE802.3bt is more energy conscious and has improved its MPS to allow a lower stand by power which is ideal to meet today’s needs.

In order to keep the port active, an IEEE802.3af or IEEE802.3at PD must draw approximately 10mA or a duty cycle of 30% from the PSE. With most systems, we would expect to see about 150mW of loss per port, so if we had multiple lighting systems on multiple ports, for example 10, this would equate to 1.5W of lost power when unit in standby. The new standard has changed this and now the PSE will only require a very conservative duty cycle of ~2%. This reduces the amount of power lost per port by a factor of 15. This is beneficial where devices can be put into sleep mode i.e. PoE lighting systems or security systems that may only be needed to be active during night time and turned off during the day.

Automatic Classification -Auto classification is a new system in which the PSE can automatically detect the actual maximum power drawn by the PD. The PSE will measure the maximum power drawn by the PD over a set amount of time and then assign this power to that port plus some margin.

Backwards Compatibility -As with 802.3at, the 802.3bt standard will be fully backwards compatible with the previous standards of PoE. This system, in theory, should work automatically with any PD (As long as the PSE has the means to supply the required power). In the scenario where an 802.3bt PD is plugged into a lower standard PSE, the device may turn on if the power consumed is within the PSE power limitations, but will fail to start or shutdown if its power is much greater than the PSE’s power capability.

802.3bt Applications

* LED Lighting * Industrial PCs * Automated Teller Machine (ATM)
* LED displays * POS terminals * IoT access points
* Automated Teller Machine (ATM) * Smart IP Cameras * Automation Control Systems

Considerations – When using higher power applications

As with every product produced, there must be considerations made. As the new standard is released and we start to see an influx of new designs, it is important to consider the thermal requirements of the PD. In this new age of technology, size is everything. Products and devices are getting smaller and slimmer, as such it is important to monitor and rectify the thermal implications of high power designs. Heatsinks and thermal management are a must and are more important than ever. With the amount of power almost tripling, internal temperatures of devices will rise much quicker. PD placing within the enclosure becomes a vital factor in being able to operate the device at its maximum operating power, such that maximum airflow and heatsinking can be achieved.


In conclusion 802.3bt, will bring a whole new avenue of opportunity to the world of PoE. Introducing new ways to improve LED lighting, smart homes and other connected devices. We will see new and more advanced security systems taking advantage of the new power limit. As the world continues to evolve and we develop more energy efficient devices, the list of applications for PoE will only increase.

Silvertel’s range of PoE modules will make the transition into the new standard easier than ever. With our 802.3bt compliant modules, implementation of 4 Pair PoE technology into your device will be seamless, easy and cost effective. They provide the complete solution using minimal external components.

Ag6800 - IEEE802.3bt PSE Ag5800 - IEEE802.3bt PD (12/24V output)
 Ag6800 web  Ag5800 web

pdfDownload this document

Silvertels Shrinking POE

The ever shrinking world of POE from Silvertel and the new Ag9900M.


This tiny ultra-miniature POE PD module is truly the smallest POE module and POE solution in the world. Capable of delivering up to 12W of power, and even rated for up to 12W at 85°C, it packs an incredible performance into the smallest of spaces. It is the culmination of years of development in high power and size reduction from Silvertel……

We said in our last article about solar power energy harvesting that there many trends in electronics. One such long standing and pervasive trend is the need and drive for continual miniaturisation. With many technologies it can be relatively straightforward, but in the world of power, it’s never easy, as power components, transformers and heat dissipation all create difficult to overcome barriers to miniaturisation. Meanwhile, cutting-edge miniaturization typically becomes more expensive as sizes are reduced. Luckily, Silvertel now have years of experience in pushing the boundaries of POE back with modules for up to 100W and squeezing high power into ever smaller packages through creative and innovative engineering. This expertise has delivered the miniaturised Ag9900M series, at almost the same price point and with improved performance over the larger Ag9800M. The expertise comes in part from experience gained in producing the world’s highest power 100W POE modules. High power POE is typically used in high end AV HDBaseT applications, IP Cameras, marine sensors, access control systems and video conferencing systems. Silvertel’s SIL range of 802.3af compliant Ag9XXX modules has also been used extensively throughout the world since 2005 and the format of the modules and package will be familiar to everyone in the industry.

At first the driving force behind the evolution of the module range was to reduce cost, resulting in the Ag9700 series, the lowest cost module Silvertel produce. Then the real miniaturisation work began.


With requests and demand for smaller footprints the Ag9700M, our first isolated SMT package POE module was designed and released. While well received, the height of the Ag9700M series (18mm) was a restricting factor, using the standard transformer package from earlier Silvertel ranges. With IOT applications such as sensors and home automation systems requiring small packages and fingerprint readers housings continuing to shrink, pressure to further reduce package sizes continued. The Silvertel engineering team embraced the challenge, to produce an even smaller footprint and lower profile SMT package POE, Ag9800M, using a new much smaller transformer. The re-design created the smallest ever POE module in a tiny footprint, Ag9800 series.

Amazingly, Silvertel’s engineering team identified during the Ag9800 design, that significant further reductions were still possible, through improvements in efficiency and an even smaller footprint transformer.

Enter the Ag9900M: Now released, Ag9900M is the latest and truly cutting edge POE module from Silvertel.
Ag9900 has superseded the Ag9800M as the world's smallest POE module, with an
amazingly tiny 21mm x 14mm footprint.

With a rapidly increasing number of remote sensors and gateways being designed for the Internet of Things, all in increasingly small packages, with low power consumption and frequently requiring external installation, the advent of the Ag9900M is perfectly timed to deliver all the advantages of industrial temperature low power POE in the smallest of footprints.

To put the package reductions into context, the footprint size reductions from the Ag9700SIL package to the current Ag9900 ultra miniature SMT package are illustrated below:


That’s an overall package size reduction from Ag9700S to Ag9900M of 71%.

The Ag9900 is already complemented by the Ag5300, with a SIL footprint comparable to the standard Ag9700 series, Ag5300 is the worlds smallest POE+ module. For further details contact your local distributor or Silvertel.

Smallest PoE + PD with 5V output - Ag5305

Silvertel has just released a 5V output version of the Ag5300. The Ag5305 is the first PoE+ module delivering up to 20 Watts of output power at 5V that requires less than 10.3cm2 of PCB space. This is ideal for any applications where space is at a premium, such as SBCs, AI applications, Wireless IoT Access Point, touch panel IoT and intelligent lighting control units, PTZ camera, door entry system and fog computing applications.

Full Featured IEEE 802.3at 12W Low Profile Power over Ethernet (PoE) PD module Ag5305 Shortform