Linear Technology introduces the LTC4268-1, a Power over Ethernet (PoE) interface controller with a synchronous, current mode, switching regulator for delivering regulation to Powered Devices (PDs). The LTC4268-1 provides up to 35W for 2-pair systems and as much as 70W for 4-pair systems.

At the heart of the LTC4268-1 is a switching regulator optimized for isolated PoE applications. The LTC4268-1 incorporates Linear Technology’s NoOpto feedback topology to provide full IEEE 802.3 isolation without the need for optoisolator circuitry. A feedback amplifier senses the output voltage through the transformer winding during the flyback period and uses this voltage to regulate the output. The transformer isolates the load from the input supply and provides feedback, improving output transient response and overall reliability.

The LTC4268-1 offers programmable switching frequency from 50kHz to 250kHz for the power supply design. In low-noise system designs, the controller can be synchronized to an external oscillator. 

The chip is capable of handling 750mA with an on-resistance of 0.55 Ohm typ Hot Swap MOSFET. Specified over the commercial and industrial temperature ranges, the LTC4268-1 is offered in a  32-pin 7mm x 4mm thermally enhanced DFN package. Available today, pricing begins at $2.40 each in 1,000 piece quantities.