The MAX5972A provides a complete interface for a powered device (PD) to comply with the IEEE 802.3af/at standard in a power-over-Ethernet (PoE) system. The MAX5972A provides the PD with a detection signature, classification signature, and an integrated isolation power switch with inrush current control. During the inrush period, the MAX5972A limits the current to less than 180mA before switching to the higher current limit (720mA to 880mA) when the isolation power MOSFET is fully enhanced. The device features an input UVLO with wide hysteresis and long deglitch time to compensate for twisted-pair cable resistive drop and to assure glitch-free transition during power-on/-off conditions. The MAX5972A can withstand up to 100V at the input. The MAX5972A supports a 2-event classification method as specified in the IEEE 802.3at standard and provides a signal to indicate when probed by Type 2 power-sourcing equipment (PSE). The device detects the presence of a wall adapter power-source connection and allows a smooth switch over from the PoE power source to the wall power adapter. The MAX5972A also provides a power-good (PG) signal, two-step current limit and foldback, overtemperature protection, and di/dt limit. The MAX5972A is available in a 16-pin, 5mm x 5mm, TQFN power package. This device is rated over the -40°C to +85°C extended temperature range.
IEEE 802.3af/at Compliant
2-Event Classification or an External Wall Adapter Indicator Output
Simplified Wall Adapter Interface
PoE Classification 0 to 5
100V Input Absolute Maximum Rating
Inrush Current Limit of 180mA Maximum
Current Limit During Normal Operation Between 720mA and 880mA