Abstract: A communication system comprises a processing system configured to support data, voice and video communications. A docking station is coupled to the processing system and is configured to provide power and data connections to a personal computer wireless device. The personal computer wireless device is configured to provide power, data, and analog connections. The docking station is coupled to the processing system over a pair of low-voltage wires having an electrical current sufficient to power the personal computer wireless device. The pair of low-voltage wires may provide sufficient electrical current to charge a battery in the personal computer wireless device.

Abstract: There are provided a first communication time ascertaining unit that ascertains with a ping command communication delay time in communication with a smartphone, a communication state determining unit that determines whether a communication state is satisfactory in the communication with the smartphone based on the ascertained communication delay time, and a communication switching unit that switches a communication channel used for the communication with the smartphone, from one communication channel to another communication channel when the communication state in the communication with the smartphone is determined to be unsatisfactory. Therefore, the switching of the communication channel is performed only when it is ascertained that the communication state with the smartphone is unsatisfactory.

Abstract: A communications connection comprises intermediate connection points (6,11) connected by a non-conducting communications link (20), with conversion equipment in one or both intermediate points for converting communications between electrical and non-electrical carriers, and each being arranged to be powered from the respective ends (1, 12). If a metallic path (18) is present between the two intermediate points, the system can be arranged to use this for a limited connection service in the event of loss of electrical power to one or both of the intermediate points (6,11).

Abstract: A mobile power system comprises a plurality of energy sources, wherein at least one energy source is a solar powered generating device and at least one energy source is a wind powered generating device; a plurality of electronic and telecommunications components configured to receive the power generated by the plurality of energy sources and/or convert the power generated to direct current power; a plurality of batteries configured to store the direct current power; and one or more transportable housings configured to hold the plurality of energy sources, the plurality of electronic and telecommunications, and the plurality of batteries during transport of the housing, and wherein the at least one solar powered energy device and the at least one wind powered generating device are disposed remotely from the housing when the mobile power system is in operation.

Abstract: Apparatus and methods of remote powering of DSL ADMs are disclosed. In a subscriber communication node, at least communication components that enable the subscriber communication node to communicate with a network switching device, and possibly also subscriber communication components that enable one or more subscriber communication devices to communicate with the network switching device, can be powered either by a local power source or remotely through an electrically conductive twisted wire pair. A network node may derive its own power and also supply power to subscriber communication nodes through twisted wire pairs. A linear or ring topology of subscriber communication nodes can thus be kept operational, and subscriber communications can potentially also be maintained, when a local power source at one or more subscriber nodes becomes unavailable.

Abstract: Embodiments are described that include a “front end” device located remotely from a local telephone location. The front end filters DC and AC current on a telephone line to separate these signals and passes a DC current through a low resistance Low Pass Filter without traditional resistance or current limiting means. The front end also provides signaling capability isolated from the DC and audio channels by a High Pass Filter. Some embodiments also include a “back end” unit located near a local telephone location. The “back end” unit filters the DC and AC currents into at least two DC current streams. One of the DC current streams provides sufficient current to power a local telephone. The other stream(s) provides current sufficient to power an auxiliary device. The “back end” device may also provide signaling isolated from the DC and audio channels that is complementary to the “front end” signaling.

Abstract: A Power-over-Ethernet (PoE) communication system dynamically provides power and data communications over a communications link. In an enterprise environment made up of one or more personal computing devices (e.g., personal or laptop computers), a switch determines a power classification for each device via a PoE control module that can be part of, for example, a Power Source Equipment/Powered Device (PSE/PD) system or a LAN-On-Motherboard/Powered Device (LOM/PD) system. A method of classifying power for each device includes detecting a device, polling it for power requirement information using a Layer 2 data link layer, receiving power requirement information from the device, and determining a power classification for the device. Power requirement information can include battery charge status, power load, power mode, etc., of the device. Various types of data packets can be used. The method can be repeated on a periodic basis, allowing power classification to be dynamic.

Abstract: Terminals are connected via cables in a star-shaped fashion with respect to a HUB in a LAN. Each of the cables includes therein signal lines and power feed lines. The HUB includes therein a power feed section. The power feed section and the power feed lines of each cable are connected to measure a value of current which flows in the power feed lines. If it is judged based on the measured current value that the terminal connected to the corresponding cable is a telephone terminal, the power feeding to the corresponding power feed lines is continued. On the other hand, if the terminal is judged to be a terminal other than the telephone terminal, the power feeding is stopped.

Abstract: A system for powering an electric device with power drawn from a telephone line in a telephone network includes an exchange connecting a telecommunication network to a subscriber apparatus through one telephone line. The system includes a control and feeding device located at the subscriber's premises, connected between the telephone line and subscriber apparatus, and further connected to the electric device to be powered, and a logic control unit in the exchange connected between the subscriber line interface circuit of the telephone line and the telecommunication network, and a bidirectional device connected between the logic control unit and subscriber circuit for recognising and applying to the logic control unit signals received by the subscriber circuit through the telephone line, and for sending to the subscriber circuit control information generated by said logic control unit and relating to the power drawing.

Abstract: A mobile power system includes a plurality of energy sources, a plurality of electronic and telecommunications components configured to convert power generated by the plurality of energy sources to direct current (DC) power, wherein the plurality of electronic and telecommunications components condition the DC power and direct the conditioned DC power to a Public Switch Telephony Network (PSTN), and one or more transportable housings configured to hold the plurality of energy sources and the plurality of electronic and telecommunications components during transport of the one or more housings.

Abstract: A subscriber line interface circuit apparatus includes tip/ring sense circuitry generating a tip sense signal and a ring sense signal from three sensed currents, wherein the tip sense signal and the ring sense signal correspond to subscriber loop tip and ring currents, respectively. In one embodiment, the tip/ring sense circuitry includes a current mirror generating first and second mirrored sense currents from a first sense current proportional to a battery feed node voltage of a subscriber loop. Current differencing circuitry provides the tip sense signal from a difference between the first mirrored sense current and a second sense current associated with a tip line of the subscriber loop. The current differencing circuitry provides the ring sense signal from a difference between the second mirrored sense current and a third sense current associated with a ring line of the subscriber loop.

Abstract: Apparatus and methods of remote powering of DSL ADMs are disclosed. In a subscriber communication node, at least communication components that enable the subscriber communication node to communicate with a network switching device, and possibly also subscriber communication components that enable one or more subscriber communication devices to communicate with the network switching device, can be powered either by a local power source or remotely through an electrically conductive twisted wire pair. A network node may derive its own power and also supply power to subscriber communication nodes through twisted wire pairs. A linear or ring topology of subscriber communication nodes can thus be kept operational, and subscriber communications can potentially also be maintained, when a local power source at one or more subscriber nodes becomes unavailable.

Abstract: A method includes the step of providing subscriber loop pull-down circuitry operating in a first voltage domain. The subscriber loop pull-down circuitry decreases at least one of a tip and a ring line current in response to a corresponding pull-down control signal. The method further includes the step of providing control circuitry operating in a second voltage domain, wherein the first and second voltage domains are substantially distinct. The control circuitry varies the pull-down control signal to decrease a selected one of the tip and ring line currents in response to a sensed current corresponding to an associated one of a tip pull-down current and a ring pull-down current. A subscriber line interface circuit apparatus includes pull-down circuitry operating in a first voltage domain. The pull-down circuitry varies line currents of the tip and ring lines in response to a pull-down control signal provided by control circuitry operating in a second voltage domain.

Abstract: Embodiments of the present invention provide an integrated circuit (IC) having an integrated DC-DC power converter therein. This IC is operable to support the distribution of combined power and data signals in a network environment such as an Ethernet network according to protocols such as the power over Ethernet (PoE) protocol. The IC includes a DC-DC power converter, a power feed circuit, and a network physical layer (PHY) module, wherein the PHY module may contain fine line structures susceptible to damage when exposed to excessive voltages. To prevent or reduce the likelihood of damage to the PHY module from voltages supplied to the DC-DC power converter, a common substrate ground is shared between the IC components.

Abstract: Terminals are connected via cables in a star-shaped fashion with respect to a HUB in a LAN. Each of the cables includes therein signal lines and power feed lines. The HUB includes therein a power feed section. The power feed section and the power feed lines of each cable are connected to measure a value of current which flows in the power feed lines. If it is judged based on the measured current value that the terminal connected to the corresponding cable is a telephone terminal, the power feeding to the corresponding power feed lines is continued. On the other hand, if the terminal is judged to be a terminal other than the telephone terminal, the power feeding is stopped.

Abstract: Subscriber line interface circuitry includes an integrated circuit having sense inputs for a sensed tip signal and a sensed ring signal of a subscriber loop. The integrated circuit generates a subscriber loop linefeed driver control signal in response to the sensed signals. In one embodiment, A linefeed driver includes power circuitry for providing battery feed to the ring and tip nodes of the subscriber loop in accordance with the linefeed control signal. The linefeed driver includes sense circuitry providing a sensed tip signal and a sensed ring signal. The sensed tip and ring signals correspond to a tip current and a ring current of the subscriber loop. In one embodiment, the integrated circuit is a complementary metal oxide semiconductor (CMOS) integrated circuit. In one embodiment, the linefeed driver comprises only discrete components.

Abstract: A method and apparatus is provided for using a single power supply in a dual mode fashion. A ringing signal is received. A waveform power supply signal based upon the ringing signal. An unbalanced output buffering function upon the signal to be conditioned using an unbalanced buffering circuit. Performing the unbalanced output buffering function includes switching between a plurality of power levels of the waveform power supply signal to maintain a predetermined maximum voltage across a plurality of devices relating to the unbalanced buffering circuit.

Abstract: A hearing aid system including an implant (60) configured for insertion into a recess (40) formed under the skin of the retro-auricular space (50), which implant does not occlude the ear canal (30). The implant includes electronic circuitry (72), a transducer (65, e.g., speaker), antenna (64), and power source (66). The hearing aid also includes an external module (70), which module includes a microphone (163), electronics (172), antenna (164), and power source (166). A telemetry link (76) between the external module antenna and the implant antenna allows transmissions between the microphone module and the implant.

Abstract: In a line driver an input current (IINN) feeds a node (K1) which is connected to an input on an amplifier (OTA1). A further input on the amplifier (OTA1) has a reference voltage (VSGND) applied to it. The amplifier (OTA1) controls a current source (MN1) which outputs an output current (IOUTN). A current/voltage converter (R1) is connected between the node (K1) and the current source (MN1). A voltage/current converter (R2) is connected between the current source (MN1) and a ground (VSS).

Abstract: A linefeed on a subscriber loop is generated to generate a current on the subscriber loop. Whether a relationship between a voltage on the subscriber loop and a threshold voltage for an identified range of voltages satisfies a condition is identified. The linefeed on the subscriber loop is controlled to modify the current on the subscriber loop in response to identifying that the relationship between the voltage on the subscriber loop and the threshold voltage for the identified range of voltages satisfies the condition to help generate the voltage on the subscriber loop in the identified range of voltages. The identifying and controlling are continued to help generate and maintain the voltage on the subscriber loop in the identified range of voltages.

Abstract: A voltage-coupling and loop current supply mechanism controllably turns on an output transistor within the tip amplifier circuitry portion of the speech amplifier to controllably apply a prescribed voltage to the telephone line during on-hook/standby mode. This controllably applied voltage serves as a source of loop current when the phone goes off-hook. The ring lead portion of the tip/ring wireline pair is connected to a controlled current sink, which is coupled to the output of a voltage regulator referenced to the battery voltage. This controlled current sink is used to sink a prescribed loop current from the tip/ring pair when the phone goes off-hook. When the phone goes off-hook and loop current is detected, the voltage-supply mechanism provided by the tip amplifier's output transistor is terminated, and the speech amplifier is placed in its normal speech amplifier mode.

Abstract: A system and method that provides lifeline service to DSL customers when a loss-of-power message is sent to the central office from an integrated access device on the customer premise. If a predetermined number of loss-of-power messages are received then power is provided to the integrated access device from the central office. To this end, a power supply at the central office provides power through an isolator circuit to a relay. The relay is connected through to the twisted pair to the integrated access device. The data connection may also be powered in this manner or, in order to save further wattage, the data connection may be disconnected for the duration of the power outage.

Abstract: A method and apparatus in a DC-feed controller for controlling a subscriber line interface circuit controlling voltage (alternately, current) on a telephone line comprising a pair of wires. A digital feedback signal is subtracted from a predetermined voltage (alternately, current) limit digital value to provide a digital error signal that represents the difference between the voltage (alternately, current) limit digital value and the digital feedback signal. The digital error signal is multiplied by a predetermined digital gain value to provide a scaled digital error value. The scaled digital error value is integrated over time to generate an integrated digital error signal having a first predetermined number n of significant bits.

Abstract: A remote power feeding method allowing efficient remote power feeding into a network termination device in the event of a commercial power failure at a subscriber site is disclosed. When the commercial power failure occurs, a power failure signal is transmitted from the subscriber-side network termination device to the central office-side line termination device. The central office-side line termination device, when receiving the power failure signal, starts DC power feeding to the subscriber-side network termination device via the subscriber line. During the power failure, only voice communication is permitted using previously selected good channels.

Abstract: Telecommunications carrier equipment in a field cabinet can be replaced so as to allow existing carrier multiplexers to be powered by newer, smaller power supply equipment. Each carrier multiplexer has a plurality of power connections for each of a plurality of power types. The existing set of power supply equipment has a supply connection corresponding to each power connection at each power types. The power inputs of each power type for each carrier multiplexer are bridged together. A replacement set of power supply equipment has a single supply connection corresponding to each power type for each carrier. Each of the bridged power inputs for each carrier multiplexer is connected with the corresponding supply connection on the replacement set of power supply equipment for each power type.

Abstract: The invention relates to a method for distributing electric power in telecommunication central office equipment intended to operate at voltages within a determined range, according to which method the voltage of the distributed power is allowed to drop temporarily below the lowest voltage of the range.

Abstract: Terminals are connected via cables in a star-shaped fashion with respect to a HUB in a LAN. Each of the cables includes therein signal lines and power feed lines. The HUB includes therein a power feed section. The power feed section and the power feed lines of each cable are connected to measure a value of current which flows in the power feed lines. If it is judged based on the measured current value that the terminal connected to the corresponding cable is a telephone terminal, the power feeding to the corresponding power feed lines is continued. On the other hand, if the terminal is judged to be a terminal other than the telephone terminal, the power feeding is stopped.

Abstract: A ringing voltage power management circuit is configured to extract an isolated high-value intermediate voltage from a central office powered digital subscriber line through a current limiting circuit, and to charge a storage capacitor that serves as an energy reservoir for the ring generator of a subscriber line circuit. The storage capacitor and the current limiting circuit isolate the peak power drawn by the ringing load from the telephone line and translate the ringing signal's (20 Hz) ripple to the sub-Hz oscillations of the ringing cadence.

Abstract: Terminals are connected via cables in a star-shaped fashion with respect to a HUB in a LAN. Each of the cables includes therein signal lines and power feed lines. The HUB includes therein a power feed section. The power feed section and the power feed lines of each cable are connected to measure a value of current which flows in the power feed lines. If it is judged based on the measured current value that the terminal connected to the corresponding cable is a telephone terminal, the power feeding to the corresponding power feed lines is continued. On the other hand, if the terminal is judged to be a terminal other than the telephone terminal, the power feeding is stopped.

Abstract: A digital device for controlling the DC line current on a telephone line which includes a digital device that utilizes a digital filter for setting the DC line current. By controlling the DC line current digitally, software can be used to set the DC line current in accordance with predefined characteristics. Predefined characteristics can be set to accommodate varying country specifications instead of using switches to control resistors and capacitors. In addition, changes in a country's requirements can be accomplished through software, instead of changing components or redesigning a circuit board. The device also incorporates a method for maintaining DC current level during changes in digital filter characteristics. The use of software results in increased flexibility by allowing an infinite number of settings via software or software updates, and allowing changes to be made quickly and easily throughout the world.

Abstract: The feeder circuit to which the present invention pertains comprises means for regulating which serves to feed an electric current to a positive output terminal and a negative output terminal; means for feeding electric current which serves to feed an electric current to the means for regulating; means for regulator control which serves to control the electric current output from the means for regulating; a first resistance located between the negative terminal of the means for feeding electric current and the positive output terminal; and a second resistance located between the positive terminal of the means for feeding electric current and the negative output terminal.

Abstract: A power management system is interfaced with both a local utility power source and a remotely powered span, and monitors the power availability for and requirements of DDS terminal equipment. Upon detecting that local utility power is insufficient to operate the terminal equipment, a power limited converter derives power from the phone line. The span power drawn is limited to a fixed value that prevents the line from collapsing. An auxiliary capacitor stores energy from either local utility power or the span, to provide for periods of extended power operation (including ringing the phone).

Abstract: A method and system for distribution of stand-by electric power via a network separate from the standard or ordinary electric power network is disclosed. Voltages are transformed/produced in voltage sources, TR and then branched off in control devices, S, to devices, A. The devices, A, distribute the voltages to loading equipment, for instance telecommunications devices, network equipment or medical equipment. Furthermore, surveillance devices, Ö, communicate with the voltage sources, the control devices, and the devices, A, to control electronic power drains, and to transfer control orders for execution.

Abstract: A distributed voice recognition system includes a digital signal processor (DSP), a nonvolatile storage medium, and a microprocessor. The DSP is configured to extract parameters from digitized input speech samples and provide the extracted parameters to the microprocessor. The nonvolatile storage medium contains a database of speech templates. The microprocessor is configured to read the contents of the nonvolatile storage medium, compare the parameters with the contents, and select a speech template based upon the comparison. The nonvolatile storage medium may be a flash memory. The DSP may be a vocoder. If the DSP is a vocoder, the parameters may be diagnostic data generated by the vocoder. The distributed voice recognition system may reside on an application specific integrated circuit (ASIC).

Abstract: A power supply has a plurality of single line interface circuits (20, 22, 24 and 26) each connected by a respective line, to a respective telephone (4, 6, 8 and 10) or other telecommunications device. Each SLIC applies a sufficient voltage derived from a battery to the line to operate the respective telephone, and dissipate any excess power supplied by the battery. The apparatus includes common power regulation means (30), which incorporates a switch mode power supply unit (68), and which monitors the voltages being supplied by the SLICs at any one time and reduces the voltages applied to the SLICs to substantially the maximum voltage required by any one of the SLICs, thereby reducing the amount of power dissipated by the SLICs.

Abstract: The present invention is directed to an integrated battery for a portable telephone. The integrated battery includes a battery for the portable telephone and a flashlight powered by the battery. The battery has at least one exposed surface as mounted to the portable telephone and the flashlight is mounted to be substantially flush with the at least one exposed surfaces of the battery so as to project a beam of light axially of the portable telephone. The battery enclosure further includes an ON/OFF switch disposed on the at least one exposed surfaces of the battery.

Abstract: An Ethernet device power transmission system includes an input transformer, an output transformer and a pair of twisted pair conductors. The input transformer includes a pair of primaries for connection to a source of Ethernet data. The input transformer also includes a pair of secondaries, each having a center-tap. A first twisted pair conductor is connected across the first secondary, a second twisted pair conductor is connected across the second secondary and a DC-bias is provided between the respective center taps of the first and second secondaries. At the local end, the output transformer includes a first and second center-tapped primary and a first and second secondary for connection to the load device. The first and second primary center taps are connected to a power processor for extraction of DC power.

Abstract: An electronic control unit for the control of automatic watering systems having plural lines comprising an electronic circuit with a programmable processing unit for the control of a plurality of different watering lines. A manually operated selector, preferably of the rotary type, is provided, that is settable in a plurality of selectionable positions, to each one of which a specific watering cycle for the lines corresponds. By acting on the selector and on a start button, it is possible to modify the programming of the processing unit in order to associate with each single line a respective watering cycle different from the ones otherwise selectable by means of the selector.

Abstract: A telephone-system interface circuit connected to a central office via a tip line and a ring line includes a battery having a first terminal and a second terminal. A first current control circuit is connected between the tip line and the first terminal of the battery. A second current control circuit is connected between the ring line and the second terminal of the battery. The first current control circuit and the second current control circuit are equal in structure.

Abstract: A telecommunication system has a supply circuit to supply power to a telecommunication line. The telecommunication line is connected to a telecommunications subscriber device. The supply circuit has a first electronic impedance that is connected between a first voltage reference terminal and a first wire of the line, and a second electronic impedance that is connected between a second voltage reference terminal and a second wire of the line. The first electronic impedance has a first transistor, and the second electronic impedance has a second transistor. The supply circuit further has a first impedance multiplying circuit with a third transistor, and a second impedance multiplying circuit with a fourth transistor. The first impedance multiplying circuit multiplies the impedance of the first electronic impedance, and the second impedance multiplying circuit multiplies the impedance of the second electronic impedance.

Abstract: An Ethernet device power transmission system includes an input transformer, an output transformer and a pair of twisted pair conductors. The input transformer includes a pair of primaries for connection to a source of Ethernet data. The input transformer also includes a pair of secondaries, each having a center-tap. A first twisted pair conductor is connected across the first secondary, a second twisted pair conductor is connected across the second secondary and a DC-bias is provided between the respective center taps of the first and second secondaries. At the local end, the output transformer includes a first and second center-tapped primary and a first and second secondary for connection to the load device. The first and second primary center taps are connected to a power processor for extraction of DC power.

Abstract: A power converter forming part of a telephone subscriber line interface circuit selectively generates a ringing signal waveform, for supply to the line, or a supply voltage for a driver circuit for providing loop current on the line. First and second fixed frequency PWM signals are used to control the power converter, and hence the voltage which it generates, for the ringing signal waveform and the supply voltage respectively. The first PWM signal enables the power converter to provide a high power level needed for ringing signals. The second PWM signal has a lower frequency, and hence results in lower switching losses and power dissipation, and a lower duty cycle, suitable for the lower power level needed for the supply voltage, and is conveniently produced by masking pulses of the first PWM signal. The frequency of the second PWM signal is greater than 270 kHz, to avoid transmitting spectral energy to the line below this frequency.

Abstract: An improved network interface unit having a substantially smaller width than many prior art network interface units. The network interface unit comprises a single, planar circuit board assembly interconnected between incoming and outgoing telephone lines and incoming and outgoing customer premises lines. Two relays and a controller are mounted on the board. The controller monitors the transmission of data along the lines and, by activating the relays, provides communication and maintenance functions, such as loopback. The network interface unit utilizes a controller made up of (1) a processor-based software control system and (2) an integrally cooperating application specific integrated circuit. The controller may, for example, provide and monitor framing, detect and monitor signals, and convert bipolar data to unipolar data.

Abstract: A technique for powering telephone lines using an unbalanced current source and current sink; and a technique for improving attenuation/frequency distribution and return loss (impedance matching) of transformer-coupled wire-line communications circuits by using secondary series capacitance and an AC current pump signal source; and a generation of ringing voltage as positive voltage pulses with respect to a negative power supply voltage; and a technique for removal of AC power ripple by using an active linear floating filter for the purpose of powering telephone line circuits, and a technique for injection of real time tone samples into T1 transmissions circuits by use of a T1 framer idle code register.

Abstract: A communication system includes a SLIC device and a SLAC device. The SLIC device and the SLAC device cooperate to control the power level provided to a subscriber line. The SLAC device includes a digital control circuit which receives a parameter signal indicative of a first parameter of the electrical power. The digital control circuit provides a digital control signal to the SLIC device in response to a sample digital control signal and the digital parameter signal. Preferably, the digital parameter signal relates to a sensed current signal and the sample digital control signal relates to a desired voltage signal. The digital control circuit can be implemented hardware or software.

Abstract: A method for reducing frequency-related power losses in a telecommunication line interface circuit comprises operating a switching converter circuit at an optimum frequency. Determination of the optimum frequency is based upon a subscriber loop length. Particularly, the subscriber loop voltage is detected at a battery feed circuit of the line interface circuit, and used to access an optimum frequency stored in an initialized database. The optimum frequency information is received in the switching converter circuit, and determines its operating frequency.

Abstract: A ring generator circuit is included in a subscriber line interface circuit (SLIC) for providing a high voltage ring signal to a plurality of ringers at the same time. The ring generator circuit includes an adder and divider circuit connected to receive a DC offset and an AC reference signal from the SLIC. The adder and divider circuit outputs a fractionalized summed signal. That signal is supplied to a full-wave rectifier, which rectifies the fractionalized summed signal so that it is always a positive voltage. The rectified signal is supplied to a switch control circuit, a first amplifier and a second amplifier. The first and second amplifiers have the same gain, but with opposite signs or polarities. The outputs of the first and second amplifiers are sent to a commutating switch, which is controlled by an output of the switch control circuit.

Abstract: A method for controlling power losses associated with the operation of line interface circuits in telecommunications networks comprises detecting a loop current of at least one subscriber loop interconnected to at least one line interface circuit. The detected loop current is used to access a threshold voltage value from a line interface circuit database. A threshold voltage based on the threshold voltage value retrieved from the database is compared to a feedback voltage to control a duty cycle of a switching converter circuit in the line interface circuit. Controlling the duty cycle of the switching converter circuit enables control of battery voltages based on the comparison of the threshold voltage and the feedback voltage. In the preferred embodiment, the battery voltage is controlled to be a minimum voltage needed to provide a predetermined magnitude of the minimum loop current.

Abstract: A technique for powering telephone lines using an unbalance current source and current sink; and a technique for improving attenuation/frequency distribution and return loss (impedance matching) of transformer-coupled wire-line communications circuits by using secondary series capacitance and an AC current pump signal source; and a generation of ringing voltage as positive voltage pulses with respect to a negative power supply voltage; and a technique for removal of AC power ripple by using an active linear floating filter for the purpose of powering telephone line circuits, and a technique for injection of real time tone samples into T1 transmissions circuits by use of a T1 framer idle code register.

Abstract: A telephone subscriber line interface circuit includes a first circuit portion and a second circuit portion, a first battery voltage and a second battery input for receiving a second battery voltage. The second circuit portion is coupled to the second battery input. The telephone subscriber line interface circuit further includes a switch for coupling the first circuit portion to one of the first battery input and the second battery input.