IEEE 802.3bt PD Controller Offers 99% Efficiency

Recently acquired by Linear Technology, Analog Devices has announced the LT4294 IEEE 802.3bt Powered Device (PD) interface controller. Intended for applications requiring up to 71 W of delivered power, this new Power over Ethernet (PoE) standard (IEEE 802.3bt) both increases the power budget and supports 10-Gb Ethernet (10GBASE-T). The LT4294’s features, benefits, and specs:

  • Available in 10-lead MSOP and 3 mm x 3 mm DFN Packages.
  • It maintains backward compatibility with older IEEE 802.3af and 802.3at PoE equipment.
  • It provides up to 99% of power available from the RJ-45 connector to the hot swap output.
  • Supports new features: additional PD classes (5, 6, 7, and 8), PD types (Type 3 and Type 4), and five-event classification.
  • It can be married to any high efficiency switching regulator.
  • It controls an external MOSFET to reduce overall PD heat dissipation and maximize power efficiency.
  • An external MOSFET architecture enables you to size the MOSFET to your application’s requirements.
  • It’s available in industrial and automotive grades, supporting operating temperature ranges from –40°C to 85°C and –40°C to 125°C, respectively.Linear LT4294

The LT4294 starts at $1.95 each in 1,000-piece quantities and is available in production quantities. The LT4294 complements the LT4295 802.3bt PD interface controller with integrated switcher, both of which provide an upgrade path from our existing PoE+/LTPoE++ PD controllers, including the LT4276 and LT4275.

Source: Linear Technology

IEEE 802.3bt PD Controller

Linear Technology Corp. recently introduced the LT4295IEEE 802.3bt powered device (PD) interface controller for applications that require up to 71 W. The next Power over Ethernet (PoE) standard—IEEE 802.3bt—enables manufacturers to go beyond the 25.5 W allocated by the 2009 IEEE 802.3at standard. The new standard—PoE++ or 4PPoE—increases the power budget to enable new applications and features, while supporting 10GBASE-T and maintaining backward compatibility with older IEEE equipment. The LT4295 is IEEE 802.3bt (Draft 2.0) compliant and supports newly introduced features, including all additional PD classes (5, 6, 7, and 8), additional PD types (Type 3 and Type 4), and five-event classification.Linear-LT4295

The LT4295 is a single-signature 802.3bt PD controller that integrates an isolated switching regulator controller. It is capable of synchronous operation in both high-efficiency forward and no-opto flyback topologies with auxiliary power support. This simplifies front end PD designs by reducing component count and board space, which means the LT4295 can deliver power to PD loads using just one IC. Unlike traditional PD controllers, the LT4295 controls an external MOSFET to reduce overall PD heat dissipation and maximize power efficiency. You can size the MOSFET to your application’s requirements. Standard LT4295-based implementations routinely select 30-mΩ RDS(ON) MOSFETs.

The LT4295’s features and specs:

  • IEEE 802.3af/at/bt (Draft 2.0) Powered Device (PD) with Forward/Flyback Controller
  • External hot swap N-channel MOSFET for lowest power dissipation and highest system efficiency
  • Supports up to 71-W PDs
  • Five-event classification sensing
  • Superior surge protection (100-V absolute maximum)
  • Wide junction temperature range (–40° to 125°C)
  • 94% End-to-end efficiency with LT4321 ideal bridge
  • No-opto flyback operation
  • Auxiliary power support as low as 9 V
  • Available in 28-lead 4 mm × 5 mm QFN package

Source: Linear Technology