KR20050077456A - Apparatus for lightning protection in digital subscriber device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning protection device for a digital subscriber device. The present invention relates to a lightning protection circuit of a digital subscriber device, which is a device that a subscriber must have in order to receive a data exchange service according to various xDLS technologies. Regardless of the characteristics, the overvoltage caused by lightning or surge is more stably prevented from being applied to the digital subscriber device.

Description

Lightning protection device of digital subscriber device {apparatus for lightning protection in Digital Subscriber device}

The present invention relates to a lightning protection device for a digital subscriber device. More particularly, the present invention provides a digital subscriber device that is more stable than a conventional lightning protection circuit and is insensitive to device characteristics by adding a circuit configuration that eliminates overvoltage. It relates to a lightning protection device of the device.

A technique for exchanging data at high speed over a common copper wire is xDLS (xDigital Subscriber Line).

This xDSL is a technology that delivers data at high speeds over twisted-pair cables made of copper without the need to install amplifiers or repeaters along the cable path, including Asymmetric Digital Subscriber Line (ADSL) and High-bit-rate Digital Subscriber (HDSL). Lines, Single-line Digital Subscriber Lines (SDSL), Very-high-data-rate Digital Subscriber Lines (VDSLs), and Symmetric High-bitrate Digital Subscriber Lines (SHDSLs). In addition, xDSL is attracting attention because it uses telephone lines installed anywhere in the world, and is compatible with existing services such as Plain Old Telephone Service (POTS) and Integrated Services Digital Network (ISDN).

According to various xDLS technologies, a device that a subscriber must have in order to receive a data exchange service is referred to as a 'digital subscriber device'.

Digital subscriber devices typically include lightning protection circuitry to protect the device from surges and lightning strikes.

1 is a block diagram for explaining a configuration of a lightning protection device of a general digital subscriber device.

Referring to FIG. 1, a DSL line device 10, a secondary protection circuit 20, a transformer 30, and a primary boro circuit 40 are included.

The DSL line device 10 converts data transmitted from a communication terminal (not shown), which is provided with a data exchange service such as a computer, into a signal capable of transmitting a digital line, and converts a signal received from the digital line into data. To provide data exchange services to subscribers.

The secondary protection circuit 20 is connected in series with the DSL line device in each line.

The primary protection circuit 40 is composed of a poly switch and a gas discharge tube (GDT).

2 is a view for explaining the configuration of a primary protection circuit of a general digital subscriber device.

As shown in FIG. 2, the primary protection circuit 40 is composed of a GDT 41 and a plurality of polyswitches 42.

The polyswitch 42 blocks the overcurrent signal flowing through the digital line. That is, the polyswitch 42 is connected in series to each line, and if an overcurrent flows for a predetermined current or more in each line, the switch is opened to prevent the overcurrent from being applied to the digital subscriber device.

The GDT 41 cuts off the overvoltage signal flowing in the line. That is, the GDT 41 is connected in parallel to each line, and if an overvoltage exceeds a predetermined voltage due to lightning or surge, the overvoltage is not applied to the digital subscriber device, and the signal distortion is prevented.

The transformer 30 transforms the signal transmitted from the digital subscriber device to the digital line according to the turns ratio and adjusts the primary side and the secondary side impedances to prevent distortion of the signal.

At this time, the winding ratio (1: N) of the transformer 30 is set to be suitable for the strength of the signal varies depending on the type of the digital line.

The primary side and the secondary side of the transformer 30 may be the primary protection circuit 40 side and the secondary protection circuit 20 side, respectively.

The secondary protection circuit 30 is composed of a TVS diode, and if the voltage transformed by the transformer 30 is higher than the predetermined voltage Vref, the secondary protection circuit 30 is clamped to a DSL line device by clamping a voltage higher than the predetermined voltage. The voltage is prevented from going above a predetermined voltage.

However, the lightning protection circuit of the conventional digital subscriber device is characterized by the elements constituting the primary protection circuit 40 and the secondary protection circuit 20, that is, the TVS diode, the GDT 41 and the poly switch 42. As a result, cases that do not satisfy the international standards occur.

That is, the quality or characteristics of each component constituting the lightning protection circuit of the digital subscriber device is deteriorated, so that the overvoltage due to the lightning or surge cannot be prevented, and the overvoltage is applied to the digital subscriber device, thereby causing the failure or damage of the device. This problem arises.

Accordingly, the present invention has been made to solve the above problems, and by improving the lightning protection circuit of the digital subscriber device, the digital subscriber device due to lightning or surge more stably regardless of the characteristics of the elements constituting the circuit. It is an object of the present invention to provide a lightning protection device for a digital subscriber device that prevents damage.

Lightning protection device of the digital subscriber device according to an aspect of the present invention for achieving the above object is connected in parallel to a pair of signal lines to which the lightning protection circuit and the transformer is connected, thereby over-voltage of the signal provided from the lightning protection circuit And overvoltage removing means for removing.

In addition, the overvoltage control means according to the present invention is characterized in that it is composed of a dual diode to prevent the phenomenon that a signal of changing polarity is applied to a pair of signal lines.

In addition, the dual diode according to the present invention, the first voltage blocking is composed of a first forward diode having an anode terminal connected in parallel to one line of the signal line, and a first zener diode connected to the cathode terminal of the forward diode And a second voltage blocking unit including a second forward diode in which an anode terminal is connected in parallel to another line of the signal line, and a second zener diode in which an anode terminal is connected to a cathode terminal of the forward diode.

In addition, the dual diode according to the present invention has a clamping voltage value greater than the product of the maximum voltage value (2 × Vref) applied to each signal line and the winding ratio set in the transformer ( ), And a capacitance (Capacitance) is 10 pF or less.

On the other hand, the lightning protection device of the digital subscriber device according to another aspect of the present invention is connected in series with a pair of digital subscriber line (Digital Subscriber Line), when the overvoltage signal is applied from the digital subscriber line, the voltage exceeding the set voltage A first protection circuit for blocking, an overvoltage removal unit connected in parallel to a pair of signal lines connected to the first protection circuit to remove a voltage above a predetermined voltage from a signal applied to the signal line, and a series connection to the pair of signal lines A transformer for converting a signal of a predetermined voltage provided by the overvoltage removing unit according to a set turns ratio, and a second protection circuit connected in parallel to a pair of signal lines to block an overvoltage remaining in the signal transformed by the transformer. Include.

Hereinafter, a lightning protection device of a digital subscriber device according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a view for explaining the configuration of a lightning protection circuit of a digital subscriber device according to an embodiment of the present invention.

Referring to FIG. 3, the lightning protection circuit according to the present invention includes a primary protection circuit 40, a secondary protection circuit 20, a transformer 30, a DSL line device 10, and an overvoltage cancellation circuit 50. It includes.

Here, the transformer 30, the primary protection circuit 40, the secondary protection circuit 30 and the line device 10 performs the same function as the components of the conventional digital subscriber device, so the detailed description is omitted below. Let's do it.

The overvoltage removing circuit 50 is composed of a pair of TVS diodes, and each TVS diode is composed of zener diodes ZD1 and ZD2 and forward diodes D1 and D2.

In addition, the cathode terminals of the respective forward diodes D1 and D2 are connected to one line of the digital line, and the anode terminals are connected to the anode terminals of the respective zener diodes ZD1 and ZD2.

The anode terminals of the zener diodes ZD1 and ZD2 are connected to the anode terminals of the forward diodes D1 and D2, and the cathode terminals are connected to the other lines of the digital line.

In this case, the overvoltage elimination circuit 50 configures a pair of TVS diodes in a reverse direction, in which one line of the digital line has a differential signal form of a maximum voltage (Vref) and the other line of a minimum voltage (-Vref). Each of the digital lines has a positive signal and a negative signal to prepare for a change in polarity of a signal applied to each line due to lightning or surge.

It is preferable to select an element having the following characteristics as the element constituting the overvoltage removing circuit 50.

First clamping voltage ( ) Must satisfy Equation 1 below.

> 2 × Vref × N

here, ' 'Is the reference voltage clamping the voltage of the signal in the overvoltage cancellation circuit 50,' Vref 'is the maximum voltage that the digital subscriber device can be applied (-Vref is the minimum voltage),' N 'is the transformer 30 ) Turns ratio.

That is, the characteristics of each element of the overvoltage removing circuit 50 should be greater than the product of the turns ratio (1: N) and the maximum voltage (2 x Vref) between each line in order to prevent signal distortion.

Since the clamping voltage is a reference voltage for clamping the voltage of the applied signal, the signal output from the digital subscriber device to the digital line is clamped more than the maximum voltage of the signal transformed according to the turns ratio (1: N) of the transformer 30. If this is low, signal distortion may occur.

4 is a diagram illustrating a clamping voltage of an overvoltage removing circuit according to the present invention.

As shown in Fig. 4, the maximum voltage value (2 x Vref) of the signal transmitted from the DSL line device is transformed according to the turns ratio 1: N while passing through the transformer 30 (2 x Vref x N). .

However, the clamping voltage according to the device characteristics of the TCS diode constituting the overvoltage control circuit 50 ( ) Is smaller than the voltage value (2 x Vref x N) of the signal transformed in the transformer 30, the clamping voltage ( Signals higher than) are truncated, resulting in distortion in the signal transmitted over the digital line.

Therefore, the clamping voltage value of the device constituting the overvoltage removing circuit 50 ( ) Is preferably greater than the maximum voltage value (2 x Vref x N) transformed in the transformer 30.

In addition, the capacitance value should be less than 10pF minimum. That is, when the capacitance value increases, it is preferable to select an element having a value smaller than 10 pF because the communication speed of data exchanged through the line is lowered.

The operation of the lightning protection device of the digital subscriber device will be described by way of example.

First, when the voltage output from the primary protection circuit 40 is set to 300 V, and overvoltage flows in the digital line due to lightning or surge, the polyswitch 42 constituting the primary protection circuit 40 is formed. ) And the voltage of 300 V or more is removed from the primary protection circuit 40 according to the characteristics of the GDT 41 and the output of the 300 V signal.

The overvoltage removing circuit 50 lowers the 300 V voltage output from the primary protection circuit 40 to several tens of V voltages.

That is, when an overvoltage is applied to the digital line due to a lightning strike or surge, the primary protection circuit 40 removes a voltage of 300 V or more and transmits a signal having a voltage of 300 V to the first forward diode D1 of the overvoltage removal circuit 50. Is applied to the anode terminal.

When a 300 V voltage higher than the threshold voltage is applied to the first forward diode D1, the first forward diode D1 is turned on to apply a 300 V voltage to the cathode terminal of the first zener diode ZD1.

When a 300 V voltage is applied to the anode terminal, the first zener diode ZD1 applies only the set voltage to the transformer 30.

That is, the first zener diode ZD1 removes most of the voltage from the voltage of 300 V according to the characteristics of the device, and applies a signal of several tens of V voltage to the transformer 30.

On the other hand, when the voltage of the signal applied to the digital line is changed, that is, the polarity of the signal applied to the digital line is changed, a signal of 300 V voltage is applied to the anode terminal of the second forward diode D2.

Then, the second forward diode D2 is turned on to apply a signal having a voltage of 300 V to the cathode terminal of the second zener diode ZD2, and the second zener diode ZD2 at a voltage of 300 V according to the characteristics of the device. By removing most of the voltage, a signal of several tens of volts voltage is applied to the transformer 30.

The transformer 30 transforms the voltage according to the set turns ratio (1: N) and provides it to the secondary protection circuit 20, and the secondary protection circuit 20 removes the overvoltage remaining in the signal so that the DSL line device Provided by (10).

On the other hand, when a signal is provided from the DSL line device 10, the transformer 30 transforms the voltage of the signal according to the set turns ratio (1: N) in order to transmit the provided signal to the digital line, To send.

At this time, the clamping voltage of the device constituting the overvoltage control circuit 50 ( ) Is set larger than the maximum voltage value (2 x Vref x N) of the signal transmitted from the transformer 30, thereby preventing distortion of the signal.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and changes are possible within the technical spirit of the present invention, and such modifications and modifications belong to the appended claims.

As described above, according to the present invention, by improving the lightning protection circuit of the digital subscriber device, the effect of preventing damage to the digital subscriber device due to lightning or surge more stably regardless of the characteristics of the elements constituting the circuit. There is.

1 is a block diagram for explaining the configuration of a lightning protection device of a general digital subscriber device.

2 is a diagram for explaining a configuration of a primary protection circuit of a general digital subscriber device.

3 is a view for explaining the configuration of a lightning protection circuit of a digital subscriber device according to a preferred embodiment of the present invention.

4 is a view for explaining a clamping voltage of the overvoltage removing circuit according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10; DSL line device 20: secondary protection circuit

30; Transformer 40: Primary Protection Circuit

41: GDT 42: Poly switch

50: overvoltage elimination circuit D1, D1: diode

ZD1, ZD2: Zener Diode

Claims (6)

A digital subscriber device comprising a polyswitch, a lightning protection circuit composed of a gas discharge tube (GDT), and a transformer connected to the lightning protection circuit, And overvoltage removing means connected in parallel to a pair of signal lines to which the lightning protection circuit and the transformer are connected to remove an overvoltage of a signal provided from the lightning protection circuit. The method of claim 1, wherein the overvoltage control means, And a dual diode which prevents the signal from changing polarity to be applied to the pair of signal lines. The method of claim 2, wherein the dual diode, A first voltage blocking unit including a first forward diode having an anode terminal connected in parallel to one line of the signal line, and a first zener diode having an anode terminal connected to a cathode terminal of the forward diode; And a second voltage blocking unit including a second forward diode having an anode terminal connected in parallel to another line of the signal line, and a second zener diode having an anode terminal connected to a cathode terminal of the forward diode. Lightning protection device of subscriber device. The method of claim 2, wherein the dual diode, The clamping voltage value greater than the product of the maximum voltage value (2 x Vref) applied to each of the signal lines and the winding ratio set in the transformer ( Lightning protection device of a digital subscriber device characterized in that it has a). The method of claim 2, wherein the dual diode, Lightning protection device of a digital subscriber device, characterized in that the capacitance (Capacitance) is 10 pF or less. In a digital subscriber device, A first protection circuit connected in series with a pair of Digital Subscriber Lines and blocking a voltage exceeding a set voltage when an overvoltage signal is applied from the Digital Subscriber Lines; An overvoltage remover connected in parallel to a pair of signal lines connected to the first protection circuit to remove a voltage above a predetermined voltage from a signal applied to the signal line; A transformer connected in series to the pair of signal lines and transforming a signal having a predetermined voltage provided by the overvoltage removing unit according to a set turns ratio; And a second protection circuit connected in parallel to the pair of signal lines to block an overvoltage remaining in the signal transformed by the transformer.