Power Management Power-Over-Ethernet (PoE) Interface Controllers Powered Device (PD)

Powered Device (PD)

Linear Technology’s Powered Device (PD) controllers support multiple power levels of Power over Ethernet: IEEE PoE (13W), IEEE PoE+ (25.5W), and Linear Technology LTPoE++ (up to 90W) standard. PD controllers are ultimately responsible for providing the correct signature and classification to Power Sourcing Equipment (PSE), so that PSEs source the right amount of power to PDs over the Ethernet cables. Some of our PD controllers integrate efficient DC/DC converters to simplify designs, while our other PD controllers give designers the ability to choose their own DC/DC converters which helps designers achieve unique cost-efficiency requirements. Our 4th generation PD controller, the LT4275, uses an external MOSFET which allows designers to size the MOSFET per their application’s exact heating and efficiency requirements, enabling the use of low RDS(ON) MOSFETs on the order of 30mΩ. The LT4275 also has a wide -40°C to 125°C operating temperature range, 100V abs max rated port pin, and overtemperature protection to ensure robust operation.

Linear Technology’s LTPoE++ is a proprietary high power standard that uses a single CAT-5e Ethernet cable to provide four different PD power levels: 38.7W, 52.7W, 70W and 90W. These LTPoE++ power levels allow external components in the power path, such as transformers and DC/DC converters, to be sized accordingly so designs can be optimized both in terms of cost and efficiency. LTPoE++ is interoperable and backward compatible with both IEEE 802.af PoE and 802.3at PoE+ standards, so LTPoE++, PoE+ and PoE devices can all be mixed and matched. LTPoE++ has a simple plug-n-play nature, so PD and PSE controllers can seamlessly connect, classify and communicate with one another. With a complete end-to-end solution that requires no additional code, LTPoE++ PSE and PD controllers can power a wide variety of power hungry applications, including heated outdoor surveillance cameras, microwave dishes and pico cells.

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