JPH03268558A - Power feeding controlling system - Google Patents

Abstract

PURPOSE:To reduce the cost and size of a subscriber's circuit by providing a telephone exchange with a power feeding control means for A/D converting the voltages of respective nodes, inputting the converted digital signals, finding out a feedback voltage corresponding to each feeding characteristics by arithmetic processing, D/A converting respective feedback voltages, and outputting the converted analog signals to respective voltage follower circuits to control a power feeding circuit for supplying s speaking current to a subscriber's line. CONSTITUTION:The power feeding circuit is constituted of finding out feedback voltages by the arithmetic processing of a digital signal processor 21. Since the processor 21 is used for the power feeding circuit, an A/D converter 221 and a D/A converter 231 are connected to the I/O terminals of the processor 21. The output voltages of terminals 541, 542 are converted into digital signals by the A/D converters 221, 221 and the digital signals are inputted to the processor 21. The processor 21 determines prescribed feedback voltage corresponding to required feeding characteristics by executing operation based upon a previously determined program and sends digital signals corresponding to the voltages to D/A converters 231, 232. The D/A converters 231, 232 generate voltages corresponding to the applied digital signals and apply the voltages to the non-inverted inputs of operational amplifiers 521, 522.

Description

[Detailed Description of the Invention] [Summary] Regarding the power supply control method of the power supply circuit that supplies talking current to the subscriber line in a telephone exchange, the feedback voltage corresponding to the required power supply characteristics is determined by digital calculation processing, and the power supply The aim is to reduce the power consumption and size of subscriber circuits, including circuits, by supplying talking current to subscriber lines via a pair of voltage follower circuits provided corresponding to the DC power line and grounding line. A power supply means whose power supply characteristics change according to the feedback voltage given to the voltage follower circuit from each connection point with the subscriber line, and A/D conversion of each voltage at the connection point to obtain a feedback voltage corresponding to each power supply characteristic. and a power supply control means for calculating the feedback voltage through arithmetic processing, D/A converting the obtained feedback voltage, and outputting the resultant feedback voltage to the voltage follower circuit.

[Industrial application field]

The present invention relates to a power supply control system for a power supply circuit that supplies talking current to a subscriber line in a telephone exchange.

[Conventional technology]

In a power supply circuit that supplies communication current from a subscriber circuit to a subscriber line, the power supply resistance value, current limit value, and other power supply characteristics vary depending on the purpose of the exchange, customer requirements, and other factors. In addition, in telephone exchanges, subscriber circuits including such power supply circuits occupy a large portion of the equipment space of telephone exchanges, so miniaturization through LSI and other methods is progressing, and external circuits are being made smaller depending on the required power supply characteristics. A method has been adopted to deal with this issue by changing parts.

FIG. 5 is a diagram showing an example of the configuration of a conventional power supply circuit. Note that (a) shows a voltage-driven circuit configuration, and (b) shows a current-driven circuit configuration.

In FIG. 5(a), the -48■ DC power supply line is connected to the collector of the transistor 501, and the resistor (resistance value R,) 51. to the non-inverting input of operational amplifier 52, whose output is connected to the non-inverting input of transistor 50. connected to the base of The emitter of the transistor 501 is
Operational amplifier 52. It is also connected to one terminal 54I connected to the subscriber line via a resistor (resistance value R,) 53I. The terminal 541 is a resistor (resistance value Rz) 55. It is connected to the non-inverting input of operational amplifier 521 via.

In addition, the other terminal 542 is connected to the ground wire G and the subscriber line.
A similar circuit is also configured between.

Therefore, each component constituting the circuit is denoted by the same number with the subscript number "2".

A power supply circuit with such a configuration includes operational amplifiers 520 and 52.
When the voltage at the non-inverting terminal of □ is fixed, it operates as a voltage-driven power supply circuit that serves as a voltage source.

The difference between FIG. 5(b) and FIG. 5(a) is that transistors 503.
502, and is equivalent in terms of direct current.

Note that the other terminal 54□ connects the grounding wire G and the subscriber line.
A similar circuit is also configured between.

Therefore, each component constituting the circuit is denoted by the same number with the subscript number "2".

A power supply circuit having such a configuration includes an operational amplifier 52. ．． 52
When the voltage at the non-inverting terminal of □ is fixed, it operates as a current-driven power supply circuit that serves as a current source.

The characteristics of the power supply circuit having such a configuration will be explained below. Note that since each characteristic is common to each of the circuits on the -48V DC power line side and the ground line G side, the subscript numbers (", J, "2") of the reference numbers are omitted here.

The voltage output to each terminal 54 is Rl / (RI + RZ) times the voltage applied via the resistor 51,
The output resistance value of the power supply circuit viewed from the terminal 54 is R8 (RI
+R2)/RE. Therefore, for example, R1-3
When Ω is set to 0, Ω is set to Rz = 10, and R, = 50Ω, the output resistance value of the power supply circuit as seen from the subscriber line is 200Ω, and constant resistance power supply is performed.

Further, when a constant voltage diode is connected in parallel to the resistor 55, the loop current formed by the operational amplifier 52 and the resistor 53 becomes constant, so that constant current power supply characteristics can be obtained.

[Problem to be solved by the invention]

By the way, in such conventional power supply circuits, in order to obtain a feedback voltage corresponding to the required power supply characteristics, external components added to the feedback circuit are often provided by components.

Therefore, a subscriber circuit including such a feeding circuit is
Although it was made into an LSI, it was not possible to make it sufficiently compact.

An object of the present invention is to provide a power supply control method that can obtain a feedback voltage corresponding to required power supply characteristics through digital calculation processing and reduce the complexity and size of subscriber circuits including the power supply circuit. .

[Means to solve the problem] FIG. 1 is a block diagram of the principle of the present invention.

In the figure, the power supply means 11 supplies communication current to the subscriber line via a pair of voltage follower circuits provided corresponding to the DC power line and the ground line, and outputs a voltage follower from each connection point with the subscriber line. The power supply characteristics change depending on the feedback voltage applied to the circuit.

The power supply control means 13 A/D converts and takes in each voltage at the connection point, calculates a feedback voltage corresponding to each power supply characteristic through arithmetic processing, and converts the obtained feedback voltage from D/A to a voltage follower circuit. Output.

[For production]

In the present invention, the power feeding means 11 supplies a talking current to the subscriber line via a pair of voltage follower circuits provided corresponding to a predetermined DC power line and a grounding line, and the power feeding control means 13 Each voltage at the connection point between the terminal and the subscriber line is A/D converted and taken in, the feedback voltage corresponding to each power supply characteristic is determined by calculation processing, and the obtained feedback voltage is D/A converted and sent to each voltage follower. Output.

Therefore, since the feedback voltage that determines the power supply characteristics is determined by the calculation processing of the power supply control means 13, there is no need for external components to obtain the feedback voltage that corresponds to the required power supply characteristics, and the power supply circuit can be Low level of subscriber circuit including
Miniaturization can be achieved.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a diagram showing the configuration of an embodiment of the present invention.

Note that FIG. 2(a) shows a configuration in which the present invention is applied to the power feeding circuit shown in FIG. 5(a), and FIG. 2(b) shows a configuration in which the present invention is applied to the power feeding circuit shown in FIG.
) shows a configuration in which the present invention is applied to the power supply circuit shown in FIG.

In FIG. 2(a), the features of the present invention are as follows:
In the conventional power supply circuit, the resistor 55. ．． 51. The configuration is such that the feedback voltage determined by is obtained through arithmetic processing by the digital signal processing device 21. In addition, in order to use such a digital signal processing device 21, an A/D is installed at its input/output terminal.
Converter 22. and a D/A converter 231 are added.

Further, other circuits are the same as the conventional configuration shown in FIG. Note that similar digital processing is performed in the circuit corresponding to the other terminal 54□ by the A/D converter 22□, the digital signal processing device 21, and the D/A converter 232. Also, in the power supply circuit shown in FIG. 2(b), each feedback circuit is connected to the A/D converter 22. ．． 22g
, digital signal processing device 21 and D/A converter 23.
．． Similarly configured by 23□.

Below, an operation for obtaining desired power supply characteristics using a power supply circuit having such a configuration will be described.

Note that, as described above, since the same circuit is employed on both the DC power supply line side and the ground line, the subscripts "1" and "zJ" are omitted from the reference numbers of each component here.

The output voltage of the terminal 54 is converted into a digital signal by the A/D converter 22 and input to the digital signal processing device 21 . The digital signal processing device 21 determines a predetermined feedback voltage according to the required power supply characteristics by performing calculations according to a predetermined program, and transmits a digital signal corresponding to the voltage to the D/A converter 23. Send to. The D/A converter 23 generates a voltage corresponding to the applied digital signal and applies it to the non-inverting input of the operational amplifier 52.

FIG. 3 is a flowchart showing the processing procedure for obtaining constant resistance power supply characteristics.

In the figure, the digital signal processing device 21 converts the voltage from the A/D converter 22 to the terminal 54 (V, . . . ).

v r b ), and multiply each value by R I /< Rl + RZ ) corresponding to the voltage feedback rate,
The results (■o1, ■.b) are sent to each D/A converter 23.

FIG. 4 is a diagram showing a processing procedure for obtaining constant current power supply characteristics.

In the figure, the digital signal processing device 21 outputs values (■, 1, v
85), subtracts a constant value corresponding to the desired constant current value from each value, and sends the result (V, . . . vob) to the D/A converter 23.

Also, if the value obtained in this way is a negative number,
Since constant current power supply is not possible, the same calculation as when obtaining constant resistance power supply characteristics is performed, and the result (V, , , ■.b) is
/A converter 23. Note that the constant value corresponding to the constant current value described above is the value of the voltage drop that occurs across the resistor 53 due to the desired constant current.

For example, when the constant current value is 40 mA and the resistance value of resistor 53 is R8
-50Ω, it becomes 2■.

Therefore, according to this embodiment, the feedback voltage corresponding to the power supply characteristics can be determined by digital calculation processing,
By changing the processing content, it is possible to respond to requests for different power supply characteristics.

〔Effect of the invention〕

As described above, according to the present invention, the feedback voltage corresponding to the power supply characteristics can be determined by digital calculation processing, and by changing the processing contents, it is possible to respond to requests for different power supply characteristics.

In addition, since the conventional feedback circuit can be realized with a digital circuit, the number of external components that were conventionally added to the feedback circuit to meet the required power supply characteristics can be reduced and the circuit can be miniaturized. Changes in characteristics due to aging can be avoided, and operation can be stabilized. In addition, program control makes it possible to realize power supply characteristics that are more complex than conventional ones, and a digital processing section that performs such digital processing can be realized at low cost using an LSI, so that costs can be reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a diagram showing the configuration of an embodiment of the invention, Fig. 3 is a flowchart showing the processing procedure for obtaining constant resistance power supply characteristics, and Fig. 4 is a diagram showing constant current power supply characteristics. FIG. 5 is a diagram showing an example of the configuration of a conventional power supply circuit. In the figure, 11 is a power supply means, 13 is a power supply control means, 21 is a digital signal processing device, 22, . 22□ is an A/D converter, 23, . 23□ is a D/A converter, 50, 50□ are transistors, 51, . 51□, 531.53□, 55. ．． 55□,
is a resistor, 52, . 52□ is an operational amplifier, 54, . 54□ is a terminal. 3 Block diagram of the principle of the present invention Fig. 1 (a) A diagram showing the configuration of an embodiment of the present invention Fig. Flowchart showing the process for obtaining constant resistance power supply characteristics - IJ-1 Figure (a) Configuration of a conventional power supply circuit Figure (b) showing an example

Claims (1)

[Claims] (1) A communication current is supplied to the subscriber line through a pair of voltage follower circuits provided corresponding to the DC power line and the ground line, and is applied to the voltage follower circuit from each connection point with the subscriber line. A power supply means (11) whose power supply characteristics change according to the feedback voltage applied to the power supply means (11) and each voltage at the connection point is A/D converted and taken in, and a feedback voltage corresponding to each of the power supply characteristics is obtained through calculation processing. power supply control means (13) for D/A converting the feedback voltage and outputting it to the voltage follower circuit;
A power supply control method characterized by comprising: