The LTC4278 is an integrated Powered Device (PD) controller and switching regulator intended for high power IEEE 802.3at and 802.3af applications. With a wide input voltage range, the LTC4278 is specifically designed to support PD applications that include a low-voltage auxiliary power input such as a 12V wall adaptor. 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.