Circuits and methods for detecting the presence of a powered device in a powered network

摘要

Circuits and methods for detecting the presence of a powered device in a powered network connection and removing power from the powered network connection (e.g. power over ethernet) when no powered device is present are disclosed. The circuits and methods involve applying a time-varying voltage signal into an analog amplifier circuit that converts the voltage into a current indicative of the impedance of the connection. The analog amplifier circuit may be implemented with a dual-output trans-conductance amplifier that provides a digital voltage to indicate the removal of the powered device from the powered network connection.