Dell N3200-ON EMC Networking N-Series Switches User Guide version 6.6.3 - Page 77

Classification The classification process takes place immediately after PD detection has successfully completed. The goal of the classification process is to detect the PD class, as specified in IEEE802.3AF and AT standards. • In AF mode, the classification mechanism is based on a single event, and the device is classified as a Type 1 PD. • In AT mode, the classification mechanism is based on two events as defined in IEEE802.3AT-2009, and the device is classified as a Type 1 or a Type 2 PD. Port Start Up Upon a successful detection and classification process, power is applied to the load using a controlled Start Up mechanism. During this period, inrush current is limited to 425 milliampere (mA) for a typical duration of 65 milliseconds (ms), which allows PD load to charge to a steady state power condition. Overload Detection and Port Shutdown After power up, the switch automatically initializes its internal protection mechanisms. These are utilized to monitor and disconnect power from the PD in the cases where extreme conditions occur, as specified in the IEEE802.3AF/AT standard. These conditions include over-current or short ports terminals scenarios. Disconnect Detection The PoE switches support a DC Disconnect Function, per the IEEE802.3AF/AT standard. This mechanism continuously monitors load current and disconnects power in cases where the load current is below 7.5mA (typical) for more than 324 ms. IC Thermal Monitoring The PoE IC contains a thermal sensor that is sampled every 20ms so the die temperature is monitored at all times. In case the die exceeds the 150°C, the system ports will be disconnected to protect the ICs. Switch Feature Overview 77