All of Linear Technology’s next generation PD controllers offer a number of key benefits. All the PD controllers use a rugged 100V 0.7Ω HotSwap™ MOSFET to manage inrush currents. A precision dual current limit keeps inrush current within IEEE 802.3af levels to ensure interoperability with any PSE. In some applications, it is desirable to power the PD from an auxiliary power source such as a wall adapter. Auxiliary power can be injected in the PD controllers either at the PD’s input or at the power supply output. PDs can then be configured for PoE dominance or auxiliary supply dominance with an option for seamless transitions – without power disruption between PoE and auxiliary power. Under the IEEE 802.3at standard, a PD must be able to handle power received in either polarity from the data or spare pair, therefore requiring a PD to implement two diode bridges. One diode bridge alone can result in a 3% to 5% drop in efficiency, which further emphasizes the crucial need for both the PD controller and switcher to be ultra efficient or “green”.