Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-05-21
2001-04-03
Bost, Dwayne (Department: 2681)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S299000, C379S387020, C379S413000
Reexamination Certificate
active
06212411
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power supply circuit comprising a line voltage forming circuit to be coupled to a telecommunication line having a line voltage for providing a supply voltage.
The present invention also relates to a telecommunication device comprising such a power supply circuit.
2. Description of the Related Art
Furthermore the present invention concerns a method for deriving a supply voltage from a telecommunication line voltage.
Such a power supply circuit, telecommunication device and method are being applied in telecommunication, in particular telephone ICs' wired or wireless subscriber telephones, a facsimile, a Web-television having a telephone card, a personal computer having a telephone card etc. These are known from Philips Semi-conductors Application Note AN 94069. The power supply IC described therein provides for facilities of a telephone subscriber set, such as handsfree facilities, listening-in facilities, dialling features, loudspeaker features etc. The stabilised power for these facilities is being supplied by and derived from the telecommunication line voltage. However the behaviour of the line power extracted from the telecommunication line is prescribed by the national telecommunication authorities, such as the PTT in the Netherlands. Within the line voltage versus line current characteristic the DC load line is precisely defined to lie in between forbidden area's. The growth of the features however, poses increasing demands on the maximum supply voltage which is necessary for these features to function optimally.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide tools for optimum power management between, at the one hand what is allowed by the national telecommunication authorities and at the other hand what is required for the facilities to operate in their full working area.
Thereto the present invention is characterised in that the power supply circuit is provided with a sensing circuit having an input to be coupled with the telecommunication line, and an output for providing an output signal which is representative for the power taken from the telecommunication line, and that the line voltage stabiliser is provided with a stabilised facility supply voltage control input coupled with the output of the sensing circuit.
Thereto the method according to the invention is characterised in that a signal representing the power taken from the telecommunication line is being used to influence the line voltage and therewith the supply voltage.
It is an advantage of the present invention, that it provides the possibility to use the non-forbidden area to a fuller extend by providing measures to influence the lie of the load line, and in particular to position the load line as closely and as optimally as possible in the vicinity of what is prescribed to be the maximum reachable. By doing this the thus adjustable lie of the load point on the load line can be optimally adjusted to the requirements with respect to the stabilised facility supply voltage of the facilities.
According to one embodiment the power supply circuit according to the invention is characterised in that the sensing circuit is provided with a threshold means for controlling the voltage forming circuit such that its supply voltage is increased every time the power taken from the telecommunication line exceeds one or more thresholds.
Its an advantage of the embodiment of the power supply circuit according to the invention that a step-wise optimal adjustment can be effected in a relatively simple way.
REFERENCES:
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patent: 4532381 (1985-07-01), Rosenbaum et al.
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patent: 5712554 (1998-01-01), Lace
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By Philips, “Application Note, Application of the Tea 1093 Handsfree Circuit ETT/AN93015” pp. 1-67.
Labbe Eric C.
Mulder Jacob
Thus Fransiscus J. M.
Bost Dwayne
Trinh Sonny
U.S. Philips Corporation
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