IEEE 802.3af Controller Delivers Power Over Ethernet

The LTC4257 -48V, power-over-Ethernet interface controller includes all the elements needed to connect a powered device to an IEEE 802.3af powered network. These include a precision 25k signature resistance, programmable classification, power switching, inrush current limiting, and fault protection. An integrated 100V power MOSFET keeps the PD circuitry disconnected from the Ethernet cable until the input voltage reaches a valid level while inrush current limiting keeps line current below 400 mA. When the voltage across the power FET drops below 1.5V, an open-drain, power-good output indicates that the main output has reached its final value and it is safe to turn on the system. Typical power consumption is less than 13W. Available in a SO-8 package, pricing starts at $1.65 each/1,000. For further information call LINEAR TECHNOLOGY CORP., Milpitas, CA. (800) 454-6327.