Telephonic communications – Subscriber line or transmission line interface – Power supply
Reexamination Certificate
1997-11-12
2001-04-03
Isen, Forester W. (Department: 2644)
Telephonic communications
Subscriber line or transmission line interface
Power supply
C379S093360, C379S093280
Reexamination Certificate
active
06212274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to computer systems employing modems and more particularly to power supply circuits for modems.
2. Description of the Related Art
An ongoing developmental goal of manufacturers has been to reduce the power consumption of computer systems. Reducing power consumption typically reduces heat generation of the system, thereby increasing reliability and decreasing costs. Reducing power consumption has been particularly important in maximizing the operating life of battery powered portable computer systems. Battery powered portable computer systems include personal information devices (“PIDs”), hand held personal computers (“HPC”), digital assistants and smart phones.
Battery powered portable computer systems have limited use before requiring recharge or replacement of the batteries. In most cases, add-on devices, such as modems, create an additional power drain on the limited power available from the batteries. Often times, the batteries cannot provide enough power for both the portable computer system and an add-on device. Alternatively, if the batteries can provide enough power for both the computer system and add on device, the life of the battery (prior to recharge or replacement) is severely limited. In some cases, with relatively high-power add-on devices, such as a V.34 modem, the battery life is so limited that use of the add-on device is impracticable.
What is desired is an alternative power source for providing power to add-on devices and/or computer systems.
SUMMARY OF THE INVENTION
The present invention solves the problems discussed above by using an adaptive power source for extracting the maximum available power from a telephone line to supplement from an internal battery. In one embodiment, the adaptive power source determines the maximum power available from the phone line, calculates a power ratio as a function of the maximum power available on the telephone line and the power needed to operate an add-on device. The adaptive power source thereafter distributes power to the add-on device from the telephone line and/or the battery as a function of the calculated power ratio. In one embodiment, the adaptive power supply provides all the power to the add-on device from the telephone line. Throughout this specification, a modem is used as an example of an add-on device. It is noted, however, that the present invention is applicable to any add-on device that interfaces to a telephone line.
In one embodiment, the adaptive power source is a transformer-based switching power supply. In one particular embodiment, the power provided to a modem is obtained from power extracted from the telephone line and/or the internal battery. The transformer provides electrical isolation between the telephone line and the power system of the computer system.
In an alternative embodiment, the adaptive power supply includes switched capacitors to extract power from the telephone line. In one particular embodiment, the adaptive power supply includes a pair of capacitors. At any one time, one capacitor is being charged from the telephone line while the other capacitor is providing power to the modem. At a predetermined rate, the capacitors are switched such that the capacitor that was previously being charged from the telephone line provides power to the modem and the capacitor that was previously providing power to the modem is charged by the telephone line. The switched capacitor design is a highly efficient method of power transfer and provides electrical isolation between the telephone line and the computer system.
In still another embodiment, the adaptive power source implements a non-isolated design in which power is shared from the telephone line and the internal battery. The non-isolated design does not electrically isolate the telephone line from the internal computer system but provides very low losses and high efficiency.
One advantage of the present invention is that it provides add-on devices, such as modems, with power extracted from a telephone line. Another advantage of the present invention is that it may provide all the power needed to run an add-on device from the telephone line. Still another advantage of the present invention is it determines the maximum power available from a telephone line and supplements that power with power from the computer system.
REFERENCES:
patent: 4395590 (1983-07-01), Pierce et al.
patent: 4951309 (1990-08-01), Gross et al.
patent: 5086454 (1992-02-01), Hirzel
patent: 5530748 (1996-06-01), Ohmori
Conley, Rose & Tayon, PC.
Data Race, Inc.
Isen Forester W.
Kowert Robert C.
Pendleton Brian Tyrone
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