JP3051275B2 - Power supply method for subscriber circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a subscriber circuit in an electronic telephone exchange, and more particularly to a power supply system for a subscriber circuit used for testing other devices.

[0002]

2. Description of the Related Art In a computerized telephone exchange, a subscriber circuit is used for testing another device. If the power supply rise delay time of the subscriber circuit is long, the test time becomes longer, so that the rise characteristic becomes faster. It is necessary to.

Conventionally, this type of device has been disclosed in
There is one disclosed in Japanese Patent No. 54998.

FIG. 2 is a block diagram showing an example of a configuration of a subscriber circuit of such an electronic telephone exchange.

[0005] In FIG. 2, the subscriber circuit transistors 1 and 2, resistor 3, 4 and 5, a first amplifier 6 and 7, the
A power supply circuit 19 including two amplifiers 8 and 9, a first current mirror circuit 10, a second current mirror circuit 11 and a third current mirror circuit 12, a converter 13 and a capacitor 14, and Test line (subscriber
Detecting a load current I _L supplied to the switch 22 and 23 for connection to a line) 20 on the test line 20, the load current I
A load current detection circuit 16 for sending out SCN (scanning) information indicating the presence or absence of _L , and a switch 15 for controlling a power supply circuit 19 are provided.

Therefore, the power supply circuit 19 supplies a load current I _L proportional to the control current I ₁ output from the first current mirror circuit 10 via the transistors 1 and 2 and the resistors 3 and 4. Further, the amplifier 8 and 9 voltage Va generated by the load current I _L, detects Vb, is transmitted to the transducer 13. The converter 13 sums the transmitted voltages Va and Vb, and sends a feedback current I ₂ proportional to the total voltage to the third current mirror circuit 12.

[0007] The third current mirror circuit 12 outputs a feedback current I ₃ which is proportional to the feedback current I ₂ that is input, the current to the first current mirror circuit 10 via the resistor 5 I
₅ sends the. The first current mirror circuit 10 sends out a control current I ₁ proportional to the input feedback current I ₅ to the second current mirror circuit 11.

As described above, the power supply circuit 19 is caused to perform the constant resistance power supply operation by controlling the flow of the feedback current.
The capacitor 14 prevents a feedback operation with respect to the alternating current.

The resistance 1 is applied to the test line 20 having the above configuration.
7. By connecting the loop creation switch 18 and opening and closing the loop creation switch 18, the load current _IL flows and stops. Then, the presence or absence of the load current I _L is detected by the load current detection circuit 16, and sends the SCN information as test information of the device under test. Further, the normality of the device under test is confirmed by monitoring the SCN information with the test device.

Here, a method for confirming the normality of the device under test will be described with reference to FIG.

As shown in FIG. 1, the device under test 50 has:
The subscriber circuit 40 includes a scanning circuit unit 51 that uses a memory 52 to collectively manage SCN information.
The state of the memory 52 of the device under test 50 is changed, and SCN information for confirming normal operation is transmitted. Test equipment 6
0 has a test load 21 having a resistor 17 and a switch 18 for changing the SCN information of the subscriber circuit 40, and a monitoring circuit 64 for monitoring the contents of the memory 52.

FIG. 4 shows an operation timing chart of the subscriber circuit, the device under test, and the test device described above.

In this figure, FIG.
5, FIG. 4 (b) shows the loop creation switch 18, FIG. 4 (c)
Is the load current I _L , FIG. 4D is the SCN information, and FIG.
FIG. 4F shows the test timing of the test device, FIG. 4G shows the feedback current I ₃ , and FIG.
Is the charging current I ₄ of the capacitor, and FIG.
₅ is an operation timing chart of each of FIGS.

[0014] In FIG. 4 (a), the switch 15 is turned on, the switch 15 at t ₀ from the non-powered state is turned off, can control current I ₁ flows pass of the feeder circuit 19,
The power can be supplied. Next, at t ₁ , FIG.
As shown in the figure, the loop creation switch 18 is turned on,
A loop of the test line 20 is created. When the loop is formed, the power supply is started, but the feedback current I ₃ is absorbed as the charging current I ₄ of the capacitor 14, so that the load current does not rise instantaneously, and the feedback current that gradually increases as the charging current I ₄ of the capacitor 14 gradually decreases. The load current I _L is proportional to the current I _5.
Increase. Then, when the detection threshold D _th of the load current detection circuit 16 the load current I _L exceeds (t _2), it has is transmitted as SCN information. Furthermore, the SCN information received by the device under test 50, by checking the information at t _3, to confirm the normality of the test device 50. When the loop creation switch 18 breaks the loop at t ₄ , the feedback current I ₃
Becomes zero, but a discharge current flows from the capacitor 14 via the resistor 5 to discharge the capacitor 14. In addition, 2
1 indicates a test load, and 31 and 32 indicate power supplies.

[0015]

[SUMMARY OF THE INVENTION However, in the conventional subscriber circuit described above, while not shed load current I _L, sends SCN information for the capacitor 14 is discharged, to test the device under test 50 to time, since the loop created switch 18 is closed, the load current I _L rises, because of the delay before sending the SCN information from the load current detecting circuit 16, it becomes a significant limitation with respect to the shortening of the test time .

The present invention reduces the delay time of the SCN information by eliminating the problem that the delay time of the SCN information is long and thus limits the reduction of the test time. It is an object of the present invention to provide a power supply system for a subscriber circuit which can reduce the test time of a device under test using the method.

[0017]

In order to achieve the above object, the present invention provides: [1] A voltage drop of a power supply circuit due to a load current supplied to a subscriber line is monitored, and a load current is monitored in accordance with the voltage drop. In a power supply system of a subscriber circuit having a feedback path for controlling
Provided in the feedback path, and a first current mirror circuit you output a control current, is connected to the input terminal to the output terminal of said first current mirror circuit, an output terminal is the control
A transistor that controls the load current in proportion to the current
First and second current mirror circuits that will be connected to an amplifier to operate and a second amplifier for detecting a voltage generated by the load current of the subscriber line, based on a voltage from the second amplifier a converter for outputting a feedback current Te, ON
A power terminal is connected to the converter, and an output terminal is connected to an input terminal of the first current mirror circuit, and an output terminal is connected to an input terminal of the first current mirror circuit. , in which a capacitor for blocking the feedback operation of the AC signal component, was provided and a first power source to perform constantly above a certain charge in the capacitor.

[2] Power supply to the subscriber circuit according to the above [1]
In scheme, the output end of said first current mirror circuit
Connecting the second power supply before Symbol first power source and the same capacity to the child, feeding
The electrical characteristics are kept constant .

[0019]

According to the present invention, as described above, in the subscriber circuit of the electronic telephone exchange, in order to reduce the charging current of the capacitor for preventing the feedback operation with respect to the AC signal on the return path, externally, A first power supply is provided to constantly supply current.

Further, a second power supply having the same capacity as the first power supply for continuously charging a certain amount or more is provided on the output terminal side of the first current mirror circuit.

Therefore, it is possible to reduce the delay time from the creation of the loop to the output of the SCN information which is the output of the load current detection circuit, and to reduce the test time of the device under test using this SCN information. it can.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a power supply system for a subscriber circuit according to an embodiment of the present invention. Here, the same components as those of the above-described conventional circuit are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 1, monitors the voltage drop of the power supply circuit according to the load current I _L supplied to the subscriber line 20, depending on the voltage drop, the subscriber having a feedback path for controlling the load current I _L A circuit provided in the return path.
Is the control current and the first current mirror circuit 10 of you outputs I _1, the input terminal a first current mirror circuit 10
Connected to the output terminal S _2, the output terminal a control current I
Transistor for controlling the load current I _L to be proportional to ₁
A second current mirror circuit 11 that will be connected to the first amplifier 7,6 to operate the motor 1, the voltage Va generated by the <br/> load current I _L of the subscriber line, detecting Vb Do
A second amplifier 8,9, a transducer 13 which outputs a feedback current I ₂ based on the voltage from the second amplifier 8 and 9,
An input terminal is connected to the converter 13 and an output
A third current mirror circuit 12 of the terminal is connected to the input terminal S ₁ of the first current mirror circuit, said first
Is connected to the input terminal S ₁ of the current mirror circuit 10,
A capacitor 14 for preventing the feedback operation of the AC signal component, before
And a first power supply 24 (current source) for constantly charging the capacitor 14 at a certain level or more.

As described above, the first current mirror circuit 1
0 of providing a first power supply 24 for at least a certain charge in constantly capacitor 14 to prevent feedback <br/> operation by the AC signal component that is connected to the input terminal S ₁ side.

[0026] In addition, out of the first current mirror circuit 10
The performed constantly above a certain charge to the force terminal side S ₂ side 1
Connecting the second power supply 25 of the power supply 24 of the same capacity (current source)
And keep the power supply characteristics constant.

Hereinafter, the operation of the subscriber circuit will be described with reference to FIG.
This will be described with reference to FIG.

First, as shown in FIG. 4 (a), the switch 15 is turned off, as shown in FIG. 4 (b), the loop creates switch 18 is turned on at t _1, the loop of the test line 20 is formed Then, the power supply circuit 19 starts power supply.

At this time, the capacitor 14 is discharged while the feedback current I ₃ is not flowing. However, here, the current supplied from the first power supply 24 external, for the capacitor 14 is not fully discharged, as shown in FIG. 4 (g), the charging current of the feedback current I ₃ is a capacitor 14 I
The amount of sucked as _4, as shown in dotted line in FIG. 4 (h), the less becomes minute, as shown in dotted line in FIG. 4 (i), the feedback current I ₅ flows significantly faster input to the current mirror circuit 10 . Therefore, the control current I ₁ is equal to the feedback current I ₅
It flows fast and large because it is proportional to.

Since the load current I _L is proportional to the control current I ₁ , the load current I _L also rises greatly as shown by the dotted line in FIG. In order to exceed the detection threshold _Dth of the load current detection circuit 16 earlier than before,
As shown by the dotted line in (d), the presence of SCN information is output earlier. Therefore, as shown by the dotted line in FIG.
The delay time of the SCN information in the device under test is reduced.

Therefore, as shown in FIG. 4F, the test timing of the test apparatus can be made faster.

The same current is sent from the first current mirror circuit 10 and flows through the second current mirror circuit 11 so that the power supply characteristics are not shifted by the first power supply 24 added to the capacitor 14. A second power supply 25 having the same capacity as the first power supply 24 added to the capacitor 14
May be added to the sending side of the first current mirror circuit 10.

FIG. 5 is a partial block diagram of a power supply system for a subscriber circuit according to another embodiment of the present invention.

As described above, the current is supplied to the capacitor 14. As shown in FIG. 5 , the configuration is such that the potential is higher than the connection point a between the capacitor 14 and the resistor 5 via the resistor 26. You may make it connect to the power supply 28 grade | etc.,.

The present invention is not limited to the above-described embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0036]

Effect of the Invention] As described above in detail, according to the present invention, as a capacitor to prevent feedback operation with respect to the AC signal component is not discharged, so as to connect the power supply current from the external Therefore, the delay time from the creation of the loop to the output of the SCN information, which is the output of the load current detection circuit, can be reduced, and the test time of the device under test using the SCN information can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a power supply system of a subscriber circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a subscriber circuit showing a conventional example.

FIG. 3 is a block diagram of a system for confirming the normality of a device under test according to the present invention;

FIG. 4 is an operation timing chart of a subscriber circuit, a device under test, and a test device to which the present invention is applied;

FIG. 5 is a partial block diagram of a power supply system of a subscriber circuit according to another embodiment of the present invention.

[Explanation of symbols]

5, 26 Resistance 6, 7 First amplifier 8, 9 Second amplifier 10 First current mirror circuit 11 Second current mirror circuit 12 Third current mirror circuit 13 Converter 14 Capacitor 15 Switch 16 Load current detection Circuit 18 Loop creation switch 19 Power supply circuit 20 Subscriber line (test line) 24 First power supply (current source) 25 Second power supply (current source) 28 Power supply 40 Subscriber circuit 50 Device under test 60 Test device I ₁ control Currents I ₂ , I ₃ , I ₅ Feedback current I ₄ Capacitor charging current I _L load current S ₁ input terminal S ₂ output terminal Va, Vb voltage _Dth detection threshold

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04M 19/00-19/08 H04Q 3/42 H04M 3/22-3/34

Claims (2)

(57) [Claims] 1. A power supply system for a subscriber circuit having a feedback path for controlling a load current in accordance with a voltage drop caused by a load current supplied to a subscriber line and monitoring the voltage drop. There are, (a) provided in the feedback path, and a first current mirror circuit you output a control current, is connected to the output <br/> terminal (b) input terminal of the first current mirror circuit The output terminal is proportional to the control current.
Operating the transistor controlling the load current
A second current mirror circuit that will be connected to the amplifier, a second amplifier for detecting a voltage generated by the load current of (c) the subscriber line, the voltage from; (d) the second amplifier a converter for outputting a feedback current based, a third current mirror circuit connected to an input terminal of the (e) with the input terminal connected to said transducer and an output terminal of the first current mirror circuit , (f) is connected to an input terminal of said first current mirror circuit, a capacitor for blocking a feedback operation of an AC signal component and a first power source for charging a certain level or more in constantly (g) the capacitor A power supply system for a subscriber circuit, comprising: 2. The output terminal of the first current mirror circuit
A second power supply having the same capacity as the first power supply is connected to the
2. The power supply method for a subscriber circuit according to claim 1, wherein the electric characteristics are kept constant .