Both of these problems are solved by the LT4321 ideal diode bridge controller. It replaces the two diode bridge rectifiers with low-loss N-channel MOSFET bridges to increase the available power and reduce heat dissipation in a PD. The LT4321 rectifies and smoothly combines power from both the data and spare pairs into a single, polarity-correct supply output. Circuit size and cost are reduced as the enhanced power efficiency eliminates heat sinking requirements. Power savings of ten-times or more enables PDs to stay within PoE classification levels or to add value-rich functionality while maintaining class. Carefully designed to be compliant with the IEEE 802.3 PoE specification, the LT4321’s bias current does not corrupt detection and classification. The controller is compatible with both 2-pair PoE or PoE+ and 4-pair LTPoE++TM standards.