Powered device including a detection signature resistor

A powered device comprising:

• an interface responsive to a powered network;
• a first node responsive to an external resistor;
• a switch to selectively couple the first node to a voltage supply terminal;
• a power over Ethernet (PoE) detection circuit responsive to a detection voltage from the interface and to selectively activate the switch to couple the first node to the voltage supply terminal;
• and
• a reference current generator responsive to the first node to generate a reference current related to the external resistor when the switch is inactive;
• wherein the external resistor comprises a resistor having a resistance value that is approximately 25 K-ohms.

A circuit device comprising:

• a first node responsive to an external circuit element;
• a detection controller to detect a first process and to apply a first voltage to the first node responsive to detection of the first process;
• a reference current generator to apply a second voltage to the first node to generate a reference current related to the external circuit element after the first process is completed;
• and
• a switch including a first terminal coupled to the first node, a second terminal coupled to a voltage supply terminal, and a control terminal coupled to the detection controller;
• wherein the detection controller comprises an open drain pull-down circuit coupled to the control terminal of the switch.

A power over Ethernet powered device comprising:

• a dual-use pin responsive to an external circuit component;
• first logic to apply a first voltage to the dual-use pin during a first process;
• and
• second logic to apply a second voltage to the dual-use pin after the first process is complete;
• wherein the first process comprises a powered device detection process and wherein the first logic applies the first voltage to the pin to generate a detection signature.