System and method for controlling a power budget at a power source equipment using a PHY
A system and method for controlling the delivery of power to a powered device in a Power over Ethernet Broad Reach (PoE-BR) application. Cabling power loss in a PoE-BR application is related to the resistance of the cable itself. A PHY can be designed to measure electrical characteristics (e.g., insertion loss, cross talk, length, etc.) of the Ethernet cable to enable determination of the cable resistance. The determined resistance in a broad reach cable can be used in increasing a power budget allocated to a power source equipment port.
1. A power over Ethernet system that allocates individual power budgets for each of a plurality of powered devices that are coupled to a power source equipment via a corresponding plurality of power source equipment ports, comprising:
a first cable detection component that measures one or more electrical characteristics of a first Ethernet cable that couples a first of said plurality of powered devices to a first of said plurality of power source equipment ports, said first Ethernet cable having a length that is less than 100 meters;
a second cable detection component that measures one or more electrical characteristics of a second Ethernet cable that couples a second of said plurality of powered devices to a second of said plurality of power source equipment ports, said second Ethernet cable having a length that is between 300 and 500 meters; and
a power controller that controls an allocation of a total power budget amongst said plurality of power source equipment ports by an assignment of an individual power budget to each of said plurality of power source equipment ports, said allocation of said total power budget being based on a first individual power budget that accounts for a first power loss determined for said first Ethernet cable having a length less than 100 meters using said one or more measured electrical characteristics of said first Ethernet cables, and on a second individual power budget that accounts for a second power loss determined for said second Ethernet cable having a length between 300 and 500 meters using said one or more measured electrical characteristics of said second Ethernet cable.
2. The power over Ethernet system of claim 1 , wherein said individual power budgets are determined using an Ethernet cable type.
3. The power over Ethernet system of claim 2 , wherein said individual power budgets are determined using an Ethernet cable length.
4. The power over Ethernet system of claim 1 , wherein said power controller controls an allocation of power based on a calculated Ethernet cable resistances.
5. The power over Ethernet system of claim 1 , wherein said power controller identifies power budgets allocated to each of said plurality of power source equipment ports.
6. The power over Ethernet system of claim 1 , wherein a power allocation is changed through an adjustment to a current limit.
7. A power over Ethernet method in a system that supplies power to a plurality of powered devices via a plurality of ports in a power source equipment, comprising:
upon connection of a first powered device to a first power source equipment port via a first Ethernet cable that is less than 100 meters, measuring one or more electrical characteristics of said first Ethernet cable;
determining a first individual power budget for said first power source equipment port using said one or more electrical measurements of said first Ethernet cable;
upon connection of a second powered device to a second power source equipment port via a second Ethernet cable that is between 300 and 500 meters, measuring one or more electrical characteristics of said second Ethernet cable;
determining, prior to an allocation of power to said second power source equipment port, a second individual power budget for said second power source equipment port using said one or more electrical measurements of said second Ethernet cable, wherein said second individual power budget is greater than 15.4 W and accounts for a cable power loss that is attributable to said second Ethernet cable that is between 300 and 500 meters;
controlling an assignment of portions of a total power budget available to said power sourcing equipment to said plurality of power source equipment ports, wherein said control equipment port and an assignment of said second individual power budget to said second power source equipment port; and
powering said first powered device over said first Ethernet cable that is less than 100 meters and said second powered device over said second Ethernet cable that is between 300 and 500 meters.
8. The method of claim 7 , wherein said determining said second individual power budget is based on an identified length of said second Ethernet cable.
9. The method of claim 7 , wherein said determining said second individual power budget is based on an identified type of said second Ethernet cable.
10. The method of claim 7 , wherein said determining said second individual power budget is based on a determined resistance of said second Ethernet cable.
11. The method of claim 7 , wherein said controlling comprises setting a current limit for a power source equipment port.