Patent ID: 7511930

Claim:
A powered device comprising: a rectifier circuit having two inputs to receive an input voltage from a powered network and having two output terminals to provide a rectified power supply voltage in response to the input voltage; a logic circuit coupled between the two output terminals and adapted to receive data from the powered network, the logic circuit comprising a regulator to provide a regulated power supply to a load circuit; and a power protection element coupled between the two output terminals in parallel with the logic circuit, the power protection element to protect to the logic circuit from high power transients, the power protection element comprising a circuit including a zener diode having a breakdown voltage defining a threshold voltage level and including at least one switch coupled to the zener diode, wherein, in a first mode of operation, the power protection element presents a high impedance to the two output terminals, in a second mode of operation, the power protection element has a first power protection characteristic, and in a third mode of operation, the voltage protection element has a second power protection characteristic, wherein the power protection element is adapted to reduce the rectified power supply voltage at the logic circuit when an over-voltage condition is detected and to return to the first mode of operation when the over-voltage condition is finished.