Power by Linear™/Analog Devices’ LTC4278 is an integrated powered device (PD) controller and switching regulator intended for high power IEEE 802.3at and 802.3af applications. The input voltage range of the LTC4278 is specifically designed to support PD applications that include a low-voltage auxiliary power input such as a 12 V wall adapter. The inclusion of a shutdown pin provides simple implementation of both PoE and auxiliary dominate applications. In addition, the LTC4278 supports both 1-event and 2-event classifications as defined by the IEEE, thereby allowing the use in a wide range of product configurations.

The LTC4278 synchronous, current mode, flyback controller generates multiple supply rails in a single conversion step providing for the highest system efficiency while maintaining tight regulation across all outputs. This controller includes Linear Technology’s patented no-opto feedback topology to provide full IEEE 802.3 isolation without the need of an optoisolator circuit. A true soft-start function allows graceful ramp-up of all output voltages. This device is available in a 32-pin DFN package with operating temperature ranges of -40°C to +85°C. The LTC4278 was designed for security systems, industrial controls, and dual-radio access points.