The LT4276 integrates a PD controller and an isolated switched-mode regulator controller capable of synchronous operation in both forward and flyback topologies with auxiliary power support. This integration simplifies PD designs at the input stage by reducing the number of components and board space, enabling the LT4276A (LTPoE++), LT4276B (PoE+), and LT4276C (PoE) to efficiently power PD loads using a single IC.
Linear Technology's LTPoE++ standard extends support to today's very high-power applications, such as picocell base stations, signage, and outdoor security cameras, expanding the available power to four new levels (38.7W, 52.7W, 70W, and 90W). Unlike traditional PD drivers that integrate the power MOSFET, the LT4276 controls an external MOSFET to greatly reduce the PD's overall heat dissipation and maximize power efficiency—especially important at high power levels. This innovative technique allows users to size the MOSFET based on their application's heating and efficiency requirements, enabling the use of MOSFETs with RDS(ON) values ​​as low as 30 mΩ if needed. A nominal input voltage of 100 V means the LT4276 withstands and protects PDs from most common Ethernet line transients.
The LT4276 is available in industrial and extended temperature versions, for operating temperature ranges of -40°C to 85°C and -40°C to 125°C, respectively, and comes in small, RoHS-compliant, 28-pin, 4 mm x 5 mm QFN packages. The LT4276 starts at $2.39 per unit for orders of 1,000 units and is available in production quantities. The LT4276 offers a way to upgrade existing Linear Technology PD products, such as the LT4275 LTPoE++ PD controller, and is compatible with any of Linear Technology's latest PSE controllers, including the single-port LTC4274, the four-port LTC4266, the eight-port LTC4290/71 circuit set, and the twelve-port LTC4270/71 circuit set. The LT4276 can also be used with the ideal LT4321 diode bridge driver to maximize available power and reduce heat dissipation in PDs.

More information or a quote