The LTC9111 is an IEEE 802.3cg compliant Single-Pair Power over Ethernet (SPoE) Powered Device (PD) controller. A wide 2.3V to 60V operating range capability with polarity correction make the LTC9111 particularly well suited for classification-based systems in building and factory automation.SCCP-based classification ensures full operating voltage is applied by the Power Sourcing Equipment (PSE) only when a valid PD is connected. The LTC9111 drives two external N-channel MOSFET switches during classification with micropower operation to minimize reservoir capacitor requirements. An external N-channel MOSFET switch isolates the output capacitance from the connector during classification and inrush. A voltage supervisor enables the external MOSFET when the PD input voltage exceeds the ON voltage threshold for the configured class and after a mandated delay. The EN output asserts after the controlled GATE pin ramp-up. The MOSFET is disabled if the input voltage drops below the OFF voltage threshold for the configured class. The LTC9111 drives a pair of external low-side N-channel MOSFETs with a low start-up voltage of 1.6V for polarity correction with reduced power losses.APPLICATIONSBuilding AutomationFactory AutomationSecurity SystemsTraffic Control Systems