PD Controllers with Switchers address PoE+ standards.

Press Release Summary:



Offered as interface controllers with integrated switching regulators, LTC4269-1/-2 and LTC4278 comply with IEEE 802.3at - Power over Ethernet (PoE+) - standard and are intended for Powered Device (PD) applications up to 25.5 W and beyond. They support 2-event classification, are backward-compatible with IEEE 802.3af devices, and integrate PD controller and synchronous flyback controller (LTC4269-1 and LTC4278) or synchronous forward controller (LTC4269-2).



Original Press Release:



High Power PD Controllers with Built-In Switchers Address IEEE 802.3at PoE+ Standard



MILPITAS, CA - June 30, 2009 - Linear Technology Corporation introduces the LTC4269-1, LTC4269-2 and LTC4278, IEEE 802.3at compliant Power over Ethernet (PoE+) interface controllers with integrated switching regulators for high-power Powered Device (PD) applications up to 25.5W and beyond. The new IEEE 802.3at definition, also known as the PoE+ standard, simultaneously expands the power budget and improves the classification mechanism used by Power Sourcing Equipment (PSE) and PDs to identify each other. The LTC4269 and LTC4278 support 2-event classification, are backward compatible with IEEE 802.3af devices, and open up the next level of PoE applications. These devices integrate both the PD controller and either a synchronous flyback controller (LTC4269-1 and LTC4278) or synchronous forward controller (LTC4269-2) for a complete IEEE 802.3at PD control solution.

The LTC4269 and LTC4278 cater to a new breed of applications utilizing the new PoE+ standard, including video conferencing stations, RFID readers, pan-tilt-zoom security cameras and long range wireless access points. The LTC4269 and LTC4278 distinguish PSEs and PDs as either Type 1 hardware, complying with IEEE 802.3af power levels, or Type 2 hardware, complying with IEEE 802.3at power levels, allocating power accordingly. 2-event hardware classification allows a Type 2 PSE to identify connection to a Type 2 PD and signals the PD that it can source the higher power levels associated with 802.3at power. This new classification mechanism ensures interoperability between Type 1 and Type 2 devices.

The LTC4269 and LTC4278 offer enhancements to the conventional PoE features. For efficient power allocation, users can configure a classification load current that represents the PD power classification. A shutdown pin with signature corrupt provides flexible auxiliary power supply support. A rugged 100V Hot Swap(TM) MOSFET isolates the PoE interface controller and DC/DC converter during detection and classification, while providing 100mA of inrush current for smooth power-up transitions with any PSE. The LTC4269 and LTC4278 also include complementary power good outputs, an onboard signature resistor, undervoltage lockout, soft-start ramping and comprehensive thermal protection.

The LTC4269-1 and LTC4278 integrate a synchronous flyback controller that features Linear's patented No-Opto feedback topology to provide full IEEE 802.3 isolation. In addition, the LTC4278 accommodates 10V to 57V auxiliary power to provide the ultimate in power sourcing options. The LTC4269-2 integrates a synchronous forward controller that boasts greater than 94% efficiency. All versions are offered in commercial and industrial grades, supporting operating temperature ranges from 0°C to 70°C and -40°C to 85°C, respectively, and are available in a compact, RoHS-compliant, 7mm x 4mm 32-pin DFN package.

The LTC4269-1 is priced starting at $2.40 each, and the LTC4269-2 and LTC4278 are priced starting at $2.60 each in 1,000 piece quantities. The LTC4269 and LTC4278 provide an upgrade path from Linear's existing PD products, including the IEEE 802.3af pin-compatible LTC4268-1 and are supported by Linear's deep technical expertise in PoE circuit design, ensuring a smooth transition to the new PoE+ standard. Please visit www.linear.com/PoE for samples, demo boards, applications support and further product information.

Summary of Features: LTC4269 and LTC4278

Complete 25.5W Power Interface Port for IEEE 802.3at Powered Device (PD)

PoE+ 2-Event Classification with PSE Indicator Bit

Programmable Classification Current for 802.3at (Class 4) & 802.3af (Class 0-3) PDs

Integrated Synchronous No-Opto Flyback Controller (LTC4269-1 & LTC4278) or Synchronous Forward Controller (LTC4269-2)

Adjustable Frequency from 50kHz to 250kHz (LTC4269-1 & LTC4278) & 100kHz to 500kHz (LTC4269-2)

Flexible Auxiliary Power Support Using SHDN Pin

Rugged 100V, 0.7Ohm (typ) Onboard Hot Swap(TM) MOSFET with 100mA Inrush Limit

Compact 32-Pin 7mm x 4mm DFN Package

About Linear Technology
Linear Technology Corporation, a manufacturer of high performance linear integrated circuits, was founded in 1981, became a public company in 1986 and joined the S&P 500 index of major public companies in 2000. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, µModule® products, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.
LT, LTC, LTM, µModule and are registered trademarks and Hot Swap is a trademark of Linear Technology Corp. All other trademarks are the property of their respective owners.

Contacts
North America and General Information
John Hamburger
Tel: (408) 432-1900 ext. 2419
jhamburger@linear.com

Doug Dickinson
Tel: (408) 432 1900 ext. 2233
ddickinson@linear.com

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