PD controllers handle up to 90W

July 27, 2015 | 02:17
The LT4276 is available in a 28-lead 4 x 5mm package
The LT4276 is available in a 28-lead 4 x 5mm package
Providing power via the Ethernet cable (Power over Ethernet or PoE) is becoming an increasingly popular solution to simplify wiring to remote equipment. A standard RJ45 connector can provide both high speed data and DC power. The LT4276A powered-device controller from Linear Technology allows higher power operation than existing solutions while maintaining backward compatibility with Power Source Equipment (PSE) providing power to the Powered Device (PD). The LT4276 combines a PoE PD controller and a switching regulator controller capable of either flyback or forward isolated power supply operation. A signalling protocol between the PSE and PD allows the device and source to negotiate the amount of power required or available.

The LT4276A employs Linear Technology’s LTPoE++ classification scheme, receiving 38.7 W, 52.7 W, 70 W and 90 W of power at the RJ45 connector to support operation for applications such as picocell base stations, security CCTVs and public information displays for example. Unlike conventional PD controllers with an inbuilt power MOSFET, the LT4276 controls an external MOSFET to drastically reduce overall PD heat dissipation and maximize power efficiency. This approach allows designers to specify the MOSFET according to the specific application.

The LT4276 is supplied in a 28-lead, 4×5-mm QFN package available in both industrial and extended temperature grades with operating temperature ranges of -40°C to +85°C and -40°C to +125°C, respectively. Prices start at $2.25 each in quantities of 1000 units.
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