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US 6,301,358 B1Granted
Dual-slope current battery-feed circuit
AssigneeAvaya Technology Corp.
InventorsRobert K. Chen, Dieter J. H. Knollman
Life of this patent
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AssigneeAvaya Technology Corp.
InventorsRobert K. Chen, Dieter J. H. Knollman
Estimating the term…
A dual-supply line-interface circuit (100) uses a −48V power supply (VBAT1) to drive long subscriber loops (120) and uses a −28V power supply (VBAT2) to drive short subscriber loops. For intermediate-length loops, a dual-slope current-feed profile (FIG. 4) is employed to limit the line-circuit's power dissipation. The line-interface circuit operates in an apparent constant-current mode, generating about 40 mA of differential line current using the low power supply, up to a threshold line voltage of about 25V, which is equal to the low power supply voltage minus required overhead. For longer loops, the line-interface circuit switches to a second constant-current mode, generating about 22 mA of differential current using the high power supply, which maintains the loop current constant until it drops to the 48V resistive-feed value.
A line-interface circuit for connecting to an analog telephone line comprising a pair of leads having a battery-feed circuit including circuitry that monitors line voltage across the pair of leads and further including circuitry that maintains line current flowing between the leads at a substantially constant first current value when the line voltage is exceeded by a first threshold value and maintains the current at a substantially constant second current value that is significantly smaller than the first current value when the line voltage exceeds a second threshold value, including circuitry that monitors differential said current flowing between the leads to keep said current substantially constant at the first and the second current values.
A line-interface circuit for connecting to an analog telephone line comprising a pair of leads, having a battery-feed circuit that powers the line from one of a pair of power supplies operating at significantly different voltages and that comprises
A line-interface circuit for connecting to an analog telephone line comprising a pair of leads, having a battery-feed circuit including circuitry that monitors line voltage across the pair of leads and further including circuitry that maintains line current flowing between the leads at a substantially constant first current value when the line voltage is exceeded by a first threshold value and maintains the current at a substantially constant second current value that is significantly smaller than the first current value when the line voltage exceeds a second threshold value, and the battery feed circuit further including a driver for powering the line, the driver using a first of a pair of power supplies to drive the line while the line current is at the first current value and using a second of the pair of power supplies to drive the line while the line current is at the second value, the first power supply operating at a voltage of significantly greater magnitude that a voltage at which the second power supply operates.
Dependencies are inferred from the claim text.