Patent ID: 7630490

Claim:
A method for direct current (DC) feed control for a line card capable of being coupled to a subscriber line, comprising: determining if the line card is operating in a current limit region of a direct current (DC) feed curve that includes the current limit region and at least one of an anti-saturation region and a resistance feed region, wherein the act of determining if the line card is operating in the current limit region comprises determining if a first value representative of DC current on the subscriber line is greater than a current limit value; determining a second value representative of a difference between the first value and the current limit value based on determining that the first value is greater than the current limit value; determining a representative loop voltage based on a relation between the second value and a synthesized curve, wherein the synthesized curve is in the current limit region of the DC feed curve, and wherein the synthesized curve is a linear curve with a negative slope, and wherein the relation comprises the representative loop voltage being equal to a predetermined voltage value added to a product of the slope of the synthesized curve and the second value; and applying a loop voltage to the subscriber line, wherein the loop voltage applied to the subscriber line is based on the representative loop voltage.