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The 6 Top Reasons to Consider Silvertel Power over Ethernet (PoE) Modules

Monday, June 16, 2014

What is Power over Ethernet, and How Does it Work?

Simply put, Power over Ethernet (PoE) is the passing of electronic power with data over an Ethernet cable. Have you ever needed to place a piece of equipment near the Ethernet router and didn’t have an AC outlet? PoE would have been a solution to avoid this.

In 10 and 100BASE-TX we use the data pins 1 and 2 and pins 3 and 6 on the RJ45 Ethernet connector. This is considered Mode A and can alternate with a change in polarity. These are the same two pairs used for data transmission in 10BASE-T and 100BASE-TX, allowing the provision of both power and data over only two pairs in such networks.

The other, or more common, option is the use of the unused pins 4, 5 and 7, 8 on the RJ-45. This is called Mode B. However this will not work with 1000base T (Gigabit Ethernet), as all of the wires are used on the 8 pin RJ-45. So a different injection of power technique sometimes referred to as phantom powering is used. This is completed by power sent over the same wire pairs used for data. Because electricity and data function at opposite ends of the frequency spectrum, they can travel over the same cable. Electricity has much lower frequencies and data transmissions have very high frequencies.

There is a great application note covering Gigabit Ethernet on 

Two Types of Equipment Required for PoE Designs

  1. Power Sourcing Equipment (PSE) is a device such as an Ethernet switch that provides power on the Ethernet cable. The device is called an endspan or endpoint. When the device is an intermediate or sits between a non-PoE and a PoE device it is called a midspan. For instance, an external PoE device used to inject power is called a midspan device. Applications include small cell 3G/LTE, mid-span, and digital video recorder (DVR).
  2. Powered Device (PD) is a device that is powered by a PSE and in turn uses the energy from the source. Examples are wireless access points, IP phones, and IP cameras.

Features and Benefits of Silvertel PoE Modules Versus Discrete Solutions

A discrete design cycle can take months of evaluation, engineering design time and quality control. Discrete solutions are more complex and create multiple failure points while modules are a single point of failure. Modules offer a complete tested environment and meet all of the requirements of IEEE802.11fa.  

  1. Cost Saving – PoE modules save time and money by avoiding the need for separate installation of data and power infrastructures. Cable and power equipment costs, such as the rewiring of wiring closets, can grow to hundreds or thousands of dollars per Ethernet installation. This is especially true when an electrician is called upon to install outlets.
  2. Simplicity – PoE modules are easy to implement in design. They come in different packages and offer multiple hardware options. Power is fully integrated within the module offering the Ethernet infrastructure ease of deployment in hard to get at areas, such as ceilings, attics, and walls where AC outlets are not easily accessed. PoE modules are offered for both PSE and PD equipment so a complete design at both ends can easily be implemented.
  3. Flexibility of Design – Using the flexibility of modules can extend product life cycles. Once committed to PoE modules, new applications can offer solutions to known problems as end customers find unique ways of deploying hardware. Silvertel PD modules come in both isolated and non-isolated platforms.
  4. Reliability – Modules are fully tested to both IEEE specifications and internal manufacturers’ quality and reliability standards. Modules meet the 1.5K volts isolation per the IEEE802.11af and 802.11at specifications. As a result overall system reliability is aided by meeting quality goals known as "five nines”.
  5. Power Efficiency & Safety – Modules can run as high as 98% efficient for a variety of select output power ratings. Silvertel designs and manufactures a range of PoE devices covering various power options from 12 to 200 watts without using AC voltage, only safe direct-current 48V levels.
  6. Control and Management – Modules feature internal controls for overload and short circuit protection.  Modules easily provide signature and control circuitry to give full PoE compatibility. The signature is required by the Power Sourcing Equipment (PSE) before it will provide power to the port.

Silvertel PoE modules meet all of the required needs of any Power over Ethernet design. PSE and PD devices through selected power ratings covering 30W, 60W, and 200W are available. 

If you need assistance with your PoE design, please call us at (310) 536-6190, or contact us online.



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