Power Electronics

Off-the-shelf Transformers Meet PoE standard

A series of high efficiency, small footprint, off-the-shelf power transformers from Pulse for powered device (PD) side power over Ethernet (PoE) products meet IEEE standard 802.3af. These parts have been tested and approved for use with many of the most popular PoE ICs and are available in standard output voltages from 3.3 V to 12 V. Purchasing standard PoE transformers off-the-shelf significantly reduces the lead time and cost and makes them readily available and economical for small-volume PoE applications that do not warrant the design of custom transformers.

The PoE series consists of twenty-two PD-side PoE transformers for 3-W, 7-W and 13-W output power levels. The Pulse transformers have 50% lower leakage than other PoE power transformers, reducing the need for inefficient snubber circuits and increasing overall power supply efficiency.

The PoE standard allows the PD to request one of three levels or classes of power: 3-W/Class 1, 7-W/Class 2, and 13-W/Class 3. Pulse has designed 3.3-V, 5.0-V and 12.0-V output voltage transformers at each of the three power levels. Three sizes of power transformers and three output voltage levels for each power class allow designers to select the smallest and most efficient package for the class of PoE device they are designing. The footprint of the 13-W/Class 3 output transformers is 40% smaller than competitive packages. Industry-standard footprints provide the opportunity to develop a second source, if required.

Parts in this series include the PA1130NL-PA1138NL, PA1279NL-PA1284NL, PA1253NL, PA1260NL, PA1267NL, PA1269NL, PA1276NL, PA1277NL, PA1370NL, PA1528NL, and PB2115NL. Prices start at $0.69 per unit for 100,000 units.

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