TW497346B - Method and arrangement for limiting a ringing current - Google Patents

Abstract

A ringing current (IL) in a subscriber line interface circuit (1) is limited to a desired maximum value (15) by a ringing current attenuator (3) having a control input terminal connected to a control output terminal of a current comparator (4). The comparator (4) compares a sensed value (14) of the ringing current with the desired maximum value (15). In response to that the sensed value (14) exceeds the desired maximum value (15), the attenuator (3) is controlled to reduce the ringing current such that its peak value is kept equal to or below the desired maximum value.

Description

V. Description of the invention (1) Description of the invention The present invention relates to a function of limiting the ringing current in a line interface circuit (s L 丨 c s) interface circuit (SL I Cs). BACKGROUND OF THE INVENTION In order to match the characteristics of ringing, an additional integrated surface circuit must be able to apply a dual core wire transmission wire with a proper steady ringing electrical connection. —The ringing voltage will be applied to the two ends of the line resistance, the ring load, and the resistance in series with the transmission line. Depending on the condition of the vibration resistance value, the ringing voltage will cause the ringing current Λ ringing load value to be 0.1 as shown in the ringing equivalent value (RE N), and its ^ rena is about 7 euros between: 5 = When the line is busy, a low resistance ^ ringing electrical load, so you can reduce the user's green # ξ 土 ', 疋 value, the ringing current will increase, this quietly until the ringing signal is turned off. The 樘 N stage has been completed, and I hope that I can operate the electricity in the stage of using the line: and the electricity should use the current and voice signal to the user. The ringing electricity i is set to 1; it is a voltage amplifier and a load. Chenling current is the ringing voltage divided by the wire used, especially the wire used: to the user's terminal • Generally called the vibration 'load value and conduction' 'in the transmission wire' can be between the user's internal resistance. Because the output of the circuit will be continuously maintained, it will be located at the output of the output circuit and a slave line circuit will be provided. Fifth, the description of the invention (2) In order to generate ringing, the missing current reaches 100 millimeters; In the output stage, a low-resistance load must be input in parallel when the dial-up is busy, that is, 300 mA at the user side. This is because when the ringing load, the ringing current will increase up to the power spring interface circuit generated during the phase, which will cause problems, because in the output form, it can also occur. "One of the conductors failed to connect to the ground. For example, in the case of inadvertent transmission of twin core wires, it is necessary to protect them in Dongtian. There is a ringing current limit in the line interface circuit. Ϊ ϋ 体 Γ 票 'will provide a kind of limit for the number of ringing currents that can be reached in a circuit using a line interface, to limit the ringing current only /,' but just above the desired ringing current value. The method of limiting the ringing current: ^ ^ ^ The current at the time of the control or should be able to quickly reduce the current under the dial busy π ρ, ji w Μ M ku at the same time, and maintain the desired spear king degree until the ringing signal is turned off In accordance with the method completed by the present invention, the ringing current induced will have a corresponding McCaw current, which will be reduced when the reference current is exceeded. The selected reference current will not produce any significant output phase. The risk of injury is a principle. Therefore, when a ringing current is input to a line interface circuit, it will be amplified and output to the dual core line circuit, and it is detected whether the ringing current exceeds This reference current; if exceeded, the 'ring current will be reduced to a peak value, making it equal to or lower than the reference current.

497346

Brief description of the drawings' and with reference to the drawings; as shown in the specific example of the device shown in Fig. 1, the diagrams 2a and 2b are the devices 1 shown in Fig. 1 and connected to the client (not shown in the figure: a load. RL) Connect to the line resistance and ringing load of the client as shown in Figure 1

The present invention will be described in detail below. It is shown as a ringing current limit according to the present invention, and is shown as a subscriber line interface circuit. Detailed description of the specific device Figure 1. It is shown in the circuit using the line interface) The two wires A and B are shown as the wires A and B, which are used to indicate the total. An AC ringing signal for a user terminal is to use a line interface circuit SL I C 1 via an input terminal N. This contact is connected to the input of a current amplifier 2. The private current amplifier 2 is provided with two output terminals for outputting the equivalent currents 11 and Ij to the corresponding input terminals of the controllable ringing current attenuator 3. The ringing current attenuation is 3 and a control input terminal is connected to the output terminal of a current comparator 4 through a node c. The two output terminals are connected to the corresponding input terminals of the individual current amplifier 5-6.

The node C is connected to the ground through a capacitor c 丨 connected in parallel with the resistor R 丨. The control input of the current attenuator 3 is high resistance. Therefore, the current attenuator 3 will be controlled by the voltage of C. ^ The current attenuator 3 can be used to output the equivalent oscillating currents 丨 丨, and 丨 2, which are the attenuation current values of the input current 11, I2, respectively, and are the response values of the voltage of node c. When there is no voltage at node C, I 丨, = 丨 丨 and 丨 2, = 丨 2. The current amplifiers 5 and 6 can be used according to the amplification factors + g and ― ^, respectively.

Page 7 497346 Description of the invention (4) The large ringing currents 1 1 and I 2 will respectively provide the ringing currents IL and-丨 L, which are respectively applied to the core wires through the output terminals of the corresponding current amplifiers 5 and 6. A and B. A voltage-controlled current source 8 is connected to the core wires a and ^ 'with its input terminals and to the wheel-in terminal of the current amplifier 2 with its output terminal, respectively. The voltage-controlled current source 8 will sense the line voltage VL ′ across the load R L and return an inverted signal to the current amplifier 2. Therefore, a fixed magnification will be obtained between the input ringing signal and the line voltage VL. Therefore, the ringing current IL will increase when the load RL decreases, for example, when the dial-up on the user side is busy. According to the present invention, the value of the ringing current IL will be measured by the current measuring device 7. As shown in the specific example shown in FIG. 1, the output between the current amplifier 5 and the line A will be connected across the line A. To measure the true value of the ringing current I l. Anyway, it can be understood that the value of the ringing current is indeed equal to the value that can be measured at another node, as long as the relationship with the actual ringing current IL is known, for example, at the input of the current amplifier 5, where 11, = / g, that is, part of the ringing current IL can be measured. The current measuring device 7 can output the current I 4 from the rectified ringing current I L to one of the input terminals of the current comparator 4. The other input terminal of the current comparator 4 is connected to a reference DC power source IREF and can be used to output a fixed reference current I 5. The reference current I 5 indicates the maximum allowable peak value of the ringing current I L, and the set range is that the ringing current will not cause the risk of harm to the output stage (that is, the current amplifiers 5 and 6).

497346 V. Description of the invention (5) It should be pointed out that if the ringing current measured at the input of the current amplifier 5 is as above, the reference DC power supply I REF must be scaled down to output the reference current 1 5 / g ° If the current I 4 exceeds the reference current I 5 ′, the current comparator 4 will output a control current I 3 to the node C. The current I 3 will charge the capacitor c 1 and the capacitor C1 will be discharged to the ground line via the resistor R1. At node C (that is, the control input of current attenuator 3), the voltage generated by current u will control current attenuator 3 to attenuate the ringing currents Π and I 2 in a manner proportional to the voltage value. As long as the current I 4 exceeds the reference current I $, the current comparator 4 will output the current I 3. As shown in Figs. 2a and 2b, the operation method of the device according to the specific example of the ringing current limitation of the present invention shown in Fig. 1 will be described later. As shown in Fig. 2a, the rectified ringing current 14 provided by the current measuring device 7 is input to the current comparator 4 'to be compared with the reference current I 5 provided by the direct current #IREF. As described in the part of Li Yan, after the load oscillating current IL will increase correspondingly to increase the rectification, at time 10, the client dials the line. A low-resistance load like the user's end will be connected in parallel to the negative amplifier. The increased ringing current I L will cause a current I 4 as shown in Figure 2a.

At time U ′, the amplitude of the current 14 after rectification is 2 = current 13 is generated, and 1 is caused by the current 13: it is the ground state rising, as shown in the figure. The voltage core secondary opening force will continue at 14> 15. The voltage vc at node C (4; at the control wheel input of the ringing current attenuator 3) will cause

497346 V. Description of the invention (6) The subtractor 3 reduces the ringing currents I 1 and I 2, so the amplitude can be reduced. At time t 2, I 4 < I 5. At this time, the capacitor C1 starts to discharge to a lower voltage value, as shown in Fig. 2b. In the half cycle below the ringing current, the peak of I 4 has been weakened, as shown in Figure 2a, but still exceeds I 5. Therefore, the capacitor C 1 is further charged by the current I 3, and the current attenuator 3 will further reduce the ringing current 11 and 12 °. At time 13, the peak value of I 4 should theoretically be equal to I 5. Therefore, the ringing current will be reduced very quickly to a value without any risk of causing harm to the current amplifiers 5,6.

Page 497346 Schematic description

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Claims (1)

497346 6. Scope of patent application 1. A method for limiting the ringing current to a maximum value in a line interface circuit, which is characterized in that-a ringing current value can be measured and compared with the maximum value to detect Measure whether the measured value exceeds the maximum value,-the response of the measured value exceeding the maximum value is to generate a signal proportional to the difference between the measured value and the maximum value, and-to reduce the ringing current based on the signal, so Its peak remains at or below the maximum. 2. The method of item 1 in the scope of patent application is characterized in that the true value of the ringing current can be measured. 3. —A device for limiting the ringing current to a maximum value in a line interface circuit, which is characterized by including a ringing current attenuator (3) and a control input terminal, which is connected to a current comparator (4 The comparator (4) can be used to compare the measured value of the ringing current with the maximum value. When the sensed value exceeds the maximum value, it outputs a value proportional to the difference between the measured value and the maximum value. Control the signal to the attenuator (3) to reduce the ringing current, so its -peak value will remain at or below the maximum value. 4. For the device in the scope of patent application, the characteristic is that the measured value is the true value of the oscillating current. 5. —A device for limiting ringing current in a line interface circuit (1), including a first current amplifier (2), provided with an input terminal (IN), which is used to input the ringing current, and two outputs Terminal, which is used to output the equal current (11, I 2) to the input terminals of a pair of second current amplifiers (5, 6), and its output terminal is connected to the corresponding line terminal of the dual core line to a user terminal (RL ) To pick up Page 12 497346 6. The scope of patent application is to collect the vibration current, which is characterized by having a current measuring device (7), the stomach can measure the ringing current (IL) or part of it, and generate the measured current (IL). The rectified version (14) is connected to an input terminal of the current comparator (4) at the output terminal. The current comparator (4) is provided with another input terminal, which is connected to a reference current source (IREF) to generate a The reference current (15) 'and a round output terminal connected to the control input terminal of the current attenuator (3)' are connected across the output terminal of the first current amplifier (2) and the pair of second current amplifiers (5, 6). At the input, the current comparator (4) is used to supply a control current (I3) to the current sink (3) when the measured current (IL) exceeds the reference current (I5) to reduce the equality The current (11, I 2) is the difference between the measured current (IL) and the reference current (15). Page 13