WO2020094239A1

WO2020094239A1 - Protection circuit for protecting against transient current, voltage or electrical energy

Info

Publication number: WO2020094239A1
Application number: PCT/EP2018/080776
Authority: WO
Inventors: Andreas Stiedl; Mario KOLOS; Jia Liu; Michael TABAKOV
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-11-09
Filing date: 2018-11-09
Publication date: 2020-05-14
Also published as: CN112970163A; CN112970163B

Abstract

The present invention relates to the field of transient protection, with the general purpose to avoid damage to electronic components, circuits and/or equipment. The invention provides a protection circuit to protect an electronic circuit against transient current, transient voltage or transient electrical energy. The protection circuit 100 comprises: a separation circuit 130 arranged between a primary terminal and a secondary terminal; a primary protection circuit arranged between the primary terminal and the separation circuit; and a triggering circuit coupled with the separation circuit and configured to trigger the primary protection circuit on the basis of a current, voltage and/or an electrical energy at the separation circuit, when a transient current, transient voltage or transient electrical energy is applied to the primary terminal.

Description

PROTECTION CIRCUIT FOR PROTECTING AGAINST TRANSIENT CURRENT, VOLTAGE OR ELECTRICAL ENERGY

TECHNICAL FIELD

The present invention relates to the field of transient protection, and has the general purpose to avoid damage to electronic components, circuits and/or equipment. In particular, the invention presents a protection scheme referred to as Interactive Transient Protection (ITP). To this end, the invention proposes a protection circuit for protecting an electronic circuit, component or equipment against transient current, voltage and/or electrical energy. The invention also proposes an electronic circuit arrangement, which employs the protection circuit, and finally proposes a method of providing circuit protection.

BACKGROUND

Conventional solutions for protecting electronic circuits against transient current, voltage and/or electrical energy use protection circuits including various types of Surge Protection Devices (SPDs), which may be cascaded, e.g. as primary and secondary protection circuits. Typically, they are a combination of voltage attenuation elements, such as a Metal Oxide Varistor (MOV), a Gas Discharge Tube (GDT), and a Multiple Spark Gap Device (MSGD).

FIG. 11 shows an exemplary block diagram of such a conventional solution using a protection circuit 1100. The protection circuit 1100 is connected to and protects an electronic circuit 1110, which is further connected to an energy source 1160. The protection circuit 1100 comprises a primary protection circuit 1150, which is connected to a first terminal (poles/electrodes Pl’, P2’, P3’) of the protection circuit 1100, and comprises a secondary protection circuit 1200, which is connected in parallel to the primary protection circuit 1150, and to a second terminal (poles/electrodes Sl’, S2’) of the protection circuit 1100.

All conventional solutions suffer from disadvantages, particularly of the SPDs. For instance, non-triggerable components such as MOVs are mostly too big, show ageing caused by the injected energy while doing protection, and exhibit thermal runaway. Triggerable components, such as GDTs are only usable for small voltages in communication circuits. Moreover, once ignited and driven by a source energy, they continue to stay conductive, and thus cause the so-called“follow current” problem. MSGDs show relatively slow reaction on transient voltages, which results in high peak voltages required to be filtered by passive or active circuits, such as inductors, capacitors or semiconductor switches.

SUMMARY

Embodiments of the invention are based on the observation that, triggerable conventional protection circuits are able to protect electronic circuits against transient currents if the energy involved is large enough self-trigger the protection. For transients, whose energy is below the threshold necessary for self-triggering the protection circuits are generally so low that can be absorbed by the electronic circuits without causing any damage. However, there is a range of energies, which do not cause self-triggering of the protection circuit but are large enough to cause damages to the electronic circuits. Adding further protection elements to prevent damages to the electronic circuits in the latter situation requires the use of expensive elements and would increase the cost of the protection circuit significantly.

Based on this observation, the idea underlying the embodiments is to provide an additional circuit, for instance a separation circuit, which is configured to trigger the protection also in those cases where the energy of the transient is not enough to cause self-triggering of the protection circuit.

In view of the above-mentioned disadvantages, embodiments of the invention aim to improve the conventional solutions for providing protecting against transient current, voltage and/or electrical energy.

An objective is to provide a protection circuit, which can more effectively and with a higher reaction time protect an electronic circuit against transient current, voltage or electrical energy. Further, the“follow current” problem should be avoided. Another important goal is to build the protection circuit as compact as possible. The objective is achieved by embodiments provided in the enclosed independent claims. Advantageous implementations of the embodiments are further defined in the dependent claims.

In particular, embodiments of the invention are based on a forced ignition of a primary protection circuit, e.g. comprising one or more GDTs, which is achieved with a separation circuit and a voltage build up across a triggering circuit coupled to the separation circuit. The invention also enables interaction with a source, in order to shut down its output for a short time, and subsequently turn it on again.

Thus, ITP is enabled, which implies an interaction between the electronic circuit (to be protected) and the protection circuit. The ITP provided by embodiments of the invention is beneficial, since there is more functionality with better performance compared to passive protection. For instance, ITP has a faster response time, provides slew rate independent triggering, has a lower protection level, and can use smaller decoupling inductors and smaller secondary protection devices. Thus, ITP protects an electronic circuit faster, better, with smaller protection circuits and at lower cost than passive protection, against transient current, voltage and/or electrical energy.

A first aspect of the invention provides a protection circuit configured to protect an electronic circuit against transient current, transient voltage or transient electrical energy, wherein the protection circuit comprises: a separation circuit arranged between a primary terminal and a secondary terminal; a primary protection circuit arranged between the primary terminal and the separation circuit; and a triggering circuit coupled with the separation circuit and configured to trigger the primary protection circuit on the basis of a current, voltage and/or an electrical energy at the separation circuit, when a transient current, transient voltage or transient electrical energy is applied to the primary terminal.

The protection circuit of the first aspect is configured to trigger the primary protection circuit when a transient voltage and/or a transient current is present. Thereby, it provides an effective and particularly fast protection of the electronic circuit. In particular, an amount of energy transferred from the primary terminal to the secondary terminal, i.e. to the other end of the protection circuit, is“sensed” by means of the separation circuit, and protection provided by the primary protection circuit is“automatically” triggered by means of the triggering circuit, if such a transient occurs (i.e. if energy is being transferred across the separation circuit).

The separation circuit generally separates the primary protection circuit and the secondary terminal. The separation circuit may separate the primary protection circuit from e.g. a secondary protection circuit or the electronic circuit. Separation is meant in a way that all or most of the energy is being absorbed in the primary protection circuit, and none or just a fraction of the energy is propagating further towards the secondary terminal. Since the currents and voltages are of transient nature, the easiest way of separation is by using one or many inductors, which form the connection from primary protection circuit to secondary terminal, in order to reduce the current and the voltage by limiting the rate of rise during the impulse. Any other means, i.e. superconductive wire would do the same job.

The protection circuit may comprise at least two primary terminals and at least two secondary terminals, wherein a first primary terminal may be electrically connected to a first secondary terminal and a second primary terminal may be electrically connected to a second secondary terminal, and wherein the electronic circuit may be electrically connected to the two secondary terminals.

In an implementation form of the first aspect, the separation circuit comprises at least a first inductor.

The at least one first inductor may be arranged in the electrical path between the first primary terminal and the first secondary terminal, or may be arranged in the electrical path between the second primary terminal and the second secondary terminal. The at least one first inductor provides a simple but effective implementation of the separation circuit, and can e.g. be coupled to an inductor of the triggering circuit, in order to activate the triggering circuit.

In a further implementation form of the first aspect, the protection circuit further comprises a secondary protection circuit, wherein the secondary protection circuit comprises at least one voltage limiting device cascaded to the separation circuit. The secondary protection circuit may be arranged between the separation circuit and the secondary terminal. The voltage limiting device of secondary protection circuit limits voltage, providing further protection to the electronic circuit. However, the secondary protection circuit may allow transient voltage and/or current to be transferred over the separation circuit, thus activating the triggering circuit and the primary protection circuit, respectively.

In a further implementation form of the first aspect, the at least one voltage limiting device is configured to generate a current flowing through the separation circuit, in particular the at least one first inductor of the separation circuit, when the transient current, transient voltage or transient electrical energy is applied to the primary terminal.

Thus, the separation circuit can couple to the triggering circuit, e.g. inductively. The voltage limiting device may particularly be configured to limit the voltage between the first and second secondary terminal.

In a further implementation form of the first aspect, the at least one voltage limiting device comprises at least one of the following: transient-voltage-suppression diode, a metal oxide varistor, a thyristor, a triac, a capacitor for limiting the voltage at the secondary terminal, in particular between two power rails connected to the secondary terminal.

These provide effective but low-cost solutions.

In a further implementation form of the first aspect, the triggering circuit comprises at least one second inductor coupled to the at least one first inductor; and wherein as a result of a current flowing through the first inductor when the transient current, transient voltage or transient electrical energy is applied to the primary terminal, the second inductor is configured to generate a triggering voltage for triggering the primary protection circuit to provide protection against the transient current, transient voltage or transient electrical energy.

The second inductor is able to“sense” transient voltage and/or current in the separation circuit, and consequently the triggering circuit may trigger the primary protection circuit. This can happen with a high reaction time. In a further implementation form of the first aspect, the at least one first inductor forms a primary winding of a transformer and the at least one second inductor forms a secondary winding of the transformer.

In a further implementation form of the first aspect, the second inductor has more windings compared to the first inductor.

In a further implementation form of the first aspect, the primary protection circuit comprises at least one gas discharge tube at the primary terminal; and wherein on the basis of the current, voltage and/or an electrical energy at the separation circuit when the transient current, transient voltage or transient electrical energy is applied to the primary terminal, the triggering circuit is configured to trigger the primary protection circuit by igniting the at least one gas discharge tube; in particular wherein the at least one second inductor of the triggering circuit is configured to generate the triggering voltage for igniting the at least one gas discharge tube.

The at least one gas discharge tube may electrically connect two poles (electrical contacts of the primary terminal. A GDT is small and cheap, and in the protection circuit of the first aspect its above-mentioned disadvantage of the“follow current” problem can be avoided.

In a further implementation form of the first aspect, the primary protection circuit comprises two three-terminal gas discharge tubes with a common plasma in each gas discharge tube, wherein a first terminal of a first three-terminal gas discharge tube is electrically connected to a first pole of the primary terminal, a first terminal of a second three-terminal gas discharge tube is electrically connected to a second pole of the primary terminal, a second terminal of the first three-terminal gas discharge tube is electrically connected to a second terminal of the second three-terminal gas discharge tube, and a third terminal of the first and second three-terminal gas discharge tube is electrically connected to ground; wherein the second inductor of the triggering circuit is electrically connected between ground and the node between the two three-terminal gas discharge tubes; and wherein the second inductor of the triggering circuit is configured to generate the triggering voltage for igniting the two three-terminal gas discharge tubes. The three terminals of a gas discharge tube may include a mid-electrode, a center-electrode, and an outer-electrode (tip or ring electrode). This implementation form achieves the advantages of the protection circuit of the first aspect described above. The ignition path is independent from the power path. The primary protection circuit is not influenced from the total amount of capacitance.

In a further implementation form of the first aspect, the primary protection circuit comprises two three-terminal gas discharge tubes with a common plasma in each gas discharge tube, wherein a first terminal of a first three-terminal gas discharge tube is electrically connected to a first pole of the primary terminal, a first terminal of a second three-terminal gas discharge tube is electrically connected to a second pole of the primary terminal, the second inductor of the triggering circuit is electrically connected between a second terminal of the first three-terminal gas discharge tube and a second terminal of the second three-terminal gas discharge tube, a third terminal of the first and second three- terminal gas discharge tube is electrically connected to ground; and wherein the second inductor of the triggering circuit is configured to generate the triggering voltage for igniting the two three-terminal gas discharge tubes.

This implementation form achieves the advantages of the protection circuit of the first aspect described above. The ignition path is between the two third terminals of GDT1 and GDT2. Ignition of both GDTs is always insured by the circuit loop along the second inductor.

In a further implementation form of the first aspect, the primary protection circuit comprises a capacitor that is electrical connected between the second terminal of the first three-terminal gas discharge tube and ground; and wherein the capacitor is configured to support ignition of the two three-terminal gas discharge tubes by the second inductor of the triggering circuit.

The capacitor supports the ignition of the GDTs in that there is already good ignition of the GDTs at lower transient voltages. In a further implementation form of the first aspect, the primary protection circuit comprises a four-terminal gas discharge tube, wherein a first terminal of the four-terminal gas discharge tube is electrically connected to a first pole of the primary terminal, a second terminal of the four-terminal gas discharge tube is electrically connected to a second pole of the primary terminal, a third terminal of the four-terminal gas discharge tube is electrically connected to ground, and the second inductor of the triggering circuit is electrically connected between a fourth terminal of the four-terminal gas discharge tube and ground; wherein the second inductor of the triggering circuit is configured to generate the triggering voltage for igniting the four-terminal gas discharge tube.

The four terminals of a gas discharge tube may include an upper-terminal, a lower-terminal, a right- terminal (ground terminal), and a left- terminal (trigger terminal).

This implementation form achieves the advantages of the protection circuit of the first aspect described above. There is only one GDT required, which leads to lower cost and space. Voltage and triggering optimization is possible. Ignition of the GDT can happen in various ways, but preferably between the first terminal and the third terminal.

In a further implementation form of the first aspect, the primary protection circuit comprises two capacitors; wherein a first capacitor is electrically connected between the first pole of the primary terminal and ground and a second capacitor is electrically connected between the second pole of the primary terminal and ground; and wherein the two capacitors are configured to prevent triggering of the primary protection circuit, in particular to prevent ignition of the two three-terminal gas discharge tubes or the four- terminal gas discharge tube, when a test signal is applied to the primary terminal.

The capacitors particularly prevent also triggering from fast transient signals (burst).

In a further implementation form of the first aspect, the protection circuit comprises at least one switching element arranged in an electrical path between the first terminal and second terminal, in particular between the primary protection circuit and the second terminal; wherein after lapse of a first time period, which starts with the triggering of the primary protection circuit by the triggering circuit, the switching element is configured to interrupt the electrical path for a second time period. The purpose of the switching element is to stop ignition of the GDT of the primary protection circuit once triggered. In particular, the switching element may be arranged in the electrical path between the second primary terminal and the second secondary terminal, and in particular arranged between the two secondary terminals and the secondary protection circuit. The switching element may be arranged between the separation circuit and the secondary terminal.

In a further implementation form of the first aspect, the protection circuit comprises a control circuit, wherein after lapse of the first time period the control circuit is configured to control the switching element to interrupt the electrical path for the second time period.

In a further implementation form of the first aspect, the protection circuit comprises a measurement circuit with at least one measurement element, such as a shunt resistor, arranged in an electrical path between the first terminal and second terminal, in particular between the primary protection circuit and the second terminal; wherein the measurement circuit is configured to measure a current caused by the primary protection circuit when triggered by the triggering circuit.

That is, the measurement circuit can measure a current indicative of a time, at which the GDT(s) of the primary protection circuit is triggered by triggering circuit.

In particular, the measurement circuit may be arranged in the electrical path between the first primary terminal and the first secondary terminal, or in the electrical path between the second primary terminal and the second secondary terminal, and in particular arranged between the two secondary terminals and the secondary protection circuit.

In a further implementation form of the first aspect, the control circuit is configured to determine on the basis of the current measured by the measurement circuit the time at which the primary protection circuit is triggered by the triggering circuit.

A second aspect of the invention provides an electronic circuit arrangement comprising: a protection circuit according to the first aspect or any of its implementation forms, and an electronic circuit to be protected by the protection circuit against a transient current, transient voltage or transient electrical energy, wherein the protection circuit is electrically connected to the output of the electronic circuit, wherein the electronic circuit may be electrically supplied with electrical energy by an electrical energy source which may be electrically connected to the input of the electronic circuit.

An implementation form of the second aspect, the electronic circuit comprises a control circuit, wherein after lapse of the first time period the control circuit is configured to control the switching element of the protection circuit to interrupt the electrical path for the second time period, or to control the electrical energy source to stop supplying electrical energy to the input of the electronic circuit for the second time period.

In the electronic circuit arrangement of the second aspect, the electronic circuit is protected by the protection circuit according to the advantages and effects described above with respect to the first aspect.

A third aspect of the invention provides a method of providing protection for an electronic circuit against transient current, transient voltage or transient electrical energy using a protection circuit according to the first aspect or any of its implementation forms, wherein the method comprises the step of: triggering by the triggering circuit the primary protection circuit on the basis of a current, voltage and/or an electrical energy at the separation circuit when a transient current, transient voltage or transient electrical energy is applied to the primary terminal.

That is, the method provides protection against the transient voltage and/or transient current. In particular, the method of the third aspect can have implementation forms corresponding to the implementation forms of the first aspect. The method of the third aspects achieves all advantages and effects of the protection circuit of the first aspect.

In summary, the primary protection circuit, e.g. including one or more GDTs, is used as the main protection element in the protection circuit according to an embodiment of the invention. By providing coordination to source power, the usual“follow current” problem of the GDT(s) can be avoided. Transient voltage ignites, e.g. the GDTs in, the primary protection circuit. Ignition is done by the voltage itself, and via the triggering circuit, and is dependent on the transient current. In this way, the transient current is deviated through the GDTs and away from the electronic circuit(s) to be protected. Source power can be turned off by sensing excessive current. Source power can be turned on again, after a short time - e.g. long enough to let the GDTs deionize and e.g. short enough to power the load continuously.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS The above described aspects and implementation forms of the present invention will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

FIG. 1 shows a protection circuit according to an embodiment of the invention with a primary protection circuit.

FIG. 2 shows a protection circuit according to an embodiment of the invention with a primary and a secondary protection circuit. FIG. 3 shows a protection circuit according to an embodiment of the invention with an inductor as a separation circuit and with a TVS as a voltage limiting device of a secondary protection circuit. FIG. 4 shows a protection circuit according to an embodiment of the invention with two three-terminal GDTs in the primary protection circuit.

FIG. 5 shows a protection circuit according to an embodiment of the invention with two three-terminal GDTs in the primary protection circuit.

FIG. 6 shows a protection circuit according to an embodiment of the invention with two three-terminal GDTs in the primary protection circuit. FIG. 7 shows a protection circuit according to an embodiment of the invention with a four-terminal GDT in the primary protection circuit.

FIG. 8 shows a protection circuit according to an embodiment of the invention with two parallel three-terminal GDTs in the primary protection circuit

FIG. 9 shows an electronic arrangement according to an embodiment of the invention with a protection circuit and an electronic circuit that is protected.

FIG. 10 shows a method according to an embodiment of the invention.

FIG. 11 shows a conventional protection circuit.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a protection circuit 100 according to an embodiment of the invention. The protection circuit 100 is configured to protect an electronic circuit 110 against transient current, transient voltage and/or transient electrical energy. The protection circuit 100 may comprise a primary terminal (as shown exemplarily with poles/electrodes Pl (+), P2 (-), P3 (ground)) and a secondary terminal (as shown exemplarily with poles/electrodes Sl, S2). The electronic circuit 110 may be connected to the secondary terminal (as exemplarily shown in FIG. 1), and may further be connected to an electrical energy source 160 (as also exemplarily shown in FIG. 1). The protection circuit 100 comprises a separation circuit 130, which is generally arranged between the primary terminal and the secondary terminal. The separation circuit 130 may include at least one inductor as described in more detail later.

The protection circuit 100 further comprises a primary protection circuit 150, which is generally arranged between the primary terminal and the separation circuit 130. The primary protection circuit 150 may comprise at least one GDT, particularly at the primary terminal, as described in more detail later.

Further, the protection circuit 100 comprises a triggering circuit 140, which is coupled with the separation circuit 130, and is configured to trigger the primary protection circuit 150. In particular, it is configured to trigger the primary protection circuit 150 based on a current, voltage and/or electrical energy at the separation circuit 130. This may occur at the separation circuit 130, when a transient current, transient voltage or transient electrical energy is applied to the primary terminal. The triggering of the primary protection circuit 150 protects the electronic circuit 110 from the transient current, voltage or electrical energy, since it deviates it away from the electronic circuit 110. In an example, the triggering circuit 140 may be configured to trigger the primary protection circuit 150 by igniting at least one GDT in the primary protection circuit, through which the transient current, voltage and/or energy then goes. In an example, at least one inductor of the triggering circuit 140 may generate a triggering voltage sufficient for igniting the at least one GDT of the primary protection circuit 150. The triggering is particularly fast and can already occur at small transient voltages.

FIG. 2 shows a protection circuit 100 according to an embodiment of the invention, which builds on the protection circuit 100 shown in FIG. 1. Same elements in FIG. 1 and FIG. 2 share the same reference signs and function likewise.

The protection circuit 100 shown in FIG. 2 includes further a secondary protection circuit 200. The secondary protection circuit 200 comprises at least one voltage limiting device, which is cascaded to the separation circuit 130. To this end, the secondary protection circuit 200 may be (as exemplarily shown in FIG. 2) arranged between the separation circuit 130 and the secondary terminal. The voltage limiting device of the secondary protection circuit 200 is configured to limit a voltage, thus protecting the electronic circuit 110. In particular, the at least one voltage limiting device is configured to allow a current flowing through the separation circuit 130, while protecting the electronic circuit 110 from such current, when the transient current, transient voltage or transient electrical energy is applied to the primary terminal. The current flowing in the separation circuit 130 is used to trigger the triggering circuit 140, e.g. if the separation circuit 130 comprises an inductor that is coupled with an inductor of the triggering circuit 140.

FIG. 3 shows a protection circuit 100 according to an embodiment of the invention, which builds on the protection circuits 100 shown in FIG. 1 and FIG. 2. Same elements in FIG. 1, 2 and FIG. 3 share the same reference signs and function likewise.

The protection circuit 100 of FIG. 3 includes at least an inductor Ll in the separation circuit 130. Further, the at least one voltage limiting device of the secondary protection circuit 200 device comprises specifically a transient-voltage-suppression diode TVS, in order to limit the voltage at the secondary terminal. The TVS is particularly configured to allow current flowing through the inductor Ll, when the transient current, voltage or electrical energy is applied to the primary terminal. The magnetic field induced by the inductor Ll may be employed to couple to and trigger the triggering circuit 140.

FIG. 4 shows a protection circuit 100 according to an embodiment of the invention, which builds on the protection circuit 100 shown in FIG. 3. Same elements in FIG. 3 and FIG. 4 share the same reference signs and function likewise. The protection circuit 100 of FIG. 4 includes the at least one inductor Ll of the separation circuit 130, and the TVS in the secondary protection circuit 200.

Further, in the protection circuit 100 of FIG. 4, the triggering circuit 140 comprises at least one inductor L2, which is coupled to the at least one inductor Ll . In particular, the inductor Ll may form a primary winding of a transformer, and the inductor L2 may form a secondary winding of the transformer. The inductor L2 may have more windings than the inductor LL If a current flows through the inductor Ll, particularly when transient current, voltage or electrical energy is applied to the primary terminal, a current flows in the also inductor L2, and the inductor L2 generates a triggering voltage, which is suitable to trigger the primary protection circuit 150. The primary protection circuit shown in FIG. 4 comprises two three-terminal GDTs, namely GDT1 and GDT2. In particular, each of GDT1 and GDT2 includes a common plasma shared amongst their three terminals. As particularly shown in FIG. 4, a first terminal of GDT1 is electrically connected to a first pole Pl of the primary terminal. In particular, between Pl and the separation circuit 130. A first terminal of GDT2 is electrically connected to a second pole P2 of the primary terminal. A second terminal of GDT1 is electrically connected to a second terminal of GDT2, i.e. GDT1 and GDT2 are connected in series. A third terminal of GDT1 and GDT2, respectively, is electrically connected to ground, i.e. to P3. Further, the inductor L2 of the triggering circuit 140 is electrically connected between ground and the node between GDT1 and GDT2. The inductor L2 is configured to generate the triggering voltage for igniting GDT1 and GDT2.

FIG. 5 shows a protection circuit 100 according to an embodiment of the invention, which builds on the protection circuit 100 shown in FIG. 3. Further, the protection circuit 100 of FIG. 5 is an alternative to the protection circuit 100 shown in FIG. 4. Same elements in FIG. 3, FIG. 4 and FIG. 5 share the same reference signs and function likewise. The protection circuit 100 of FIG. 5 includes the at least one inductor Ll of the separation circuit 130, and the TVS in the secondary protection circuit 200. The triggering circuit 140 also includes the at least one inductor L2.

Like the protection circuit 100 in FIG. 4, the protection circuit 100 of FIG. 5 also comprises two three-terminal GDTs, namely GDT1 and GDT2, particularly with a common plasma in each GDT. However, they are connected somewhat differently, particularly with respect to the inductor L2. In FIG. 5, particularly a first terminal of GDT1 is again electrically connected to a first pole Pl of the primary terminal. A first terminal of GDT2 is again electrically connected to a second pole P2 of the primary terminal. The inductor L2 of the triggering circuit 140 is now electrically connected between a second terminal of GDT1 and a second terminal of GDT2, i.e. GDT1 is connected via L2 to GDT2. A third terminal of GDT1 and GDT2, respectively, is electrically connected to ground (P3). The inductor L2 of the triggering circuit 140 is configured to generate the triggering voltage for igniting GDT1 and GDT2. As shown further in FIG. 5, the primary protection circuit 150 may comprise a capacitor C3 and optionally a resistance (not shown in the figures) connected in parallel to the capacitor C3, which is electrically connected between the second terminal of GTD1 and ground (pole P3). The capacitor C3 is configured to support ignition of GDT1 and GDT2 by the inductor L2 of the triggering circuit 140. In particular, due to the increased capacitance by the capacitor C3 a sequential ignition of the two GDTs is forced starting from the one without the capacitor connected in parallel (e.g. GDT2 in this embodiment). The above holds also true for all the embodiments in this disclosure.

FIG. 6 shows a protection circuit 100 according to an embodiment of the invention, which builds on the protection circuit 100 shown in FIG. 5. Same elements in FIG. 5 and FIG. 6 share the same reference signs and function likewise. In the protection circuit 100 of FIG. 6, the separation circuit 130 includes two inductors Ll and Ll’, respectively. Inductor Ll is connected between Pl and Sl, while inductor Ll’ is connected between P2 and S2. That is, the separation circuit 130 may effectively be split between first primary/secondary terminals and second primary/secondary terminals. The same arrangement is also possible in the protection circuit 100 of FIG. 4.

The protection circuits 100 of FIG. 4, 5 and 6 provide simple and effective surge and lightning protection. Further, they can be built with small devices, at low cost and can partly fit into a connector. The protection circuits 100 work very well particularly under common mode (CM) conditions, which are representative for nearly all transient voltages and currents in power systems for mobile data infrastructure. Under differential mode (DM) conditions, the two GDTs are in series and the trigger voltage is well above the maximum system voltage. For lower voltages/currents, the energy goes into the second protection circuit, i.e. TVS.

FIG. 7 shows a protection circuit 100 according to an embodiment of the invention, which builds on the protection circuit 100 shown in FIG. 3. Further, it is an alternative to the protection circuits 100 shown in FIG. 4, FIG. 5 or FIG. 6. Same elements in FIG. 3 (and FIG. 4-6) and FIG. 7 share the same reference signs and function likewise. The protection circuit 100 of FIG. 7 includes the at least one inductor Ll of the separation circuit 130, and the TVS in the secondary protection circuit 200. It also includes the at least one inductor L2 in the triggering circuit 140. The primary protection circuit 150 shown in FIG. 7 includes a four- terminal gas discharge tube GDT3. A first terminal of GDT3 is electrically connected to a first pole Pl of the primary terminal, particularly between Pl and the separation circuit 130. A second terminal of GDT3 is electrically connected to a second pole P2 of the primary terminal. A third terminal of GDT3 is electrically connected to ground, i.e. to the third pole P3. The inductor L2 of the triggering circuit 140 is electrically connected between a fourth terminal of GDT3 and ground. That is, the third terminal and the fourth terminal of GDT3 are connected via L2. The inductor L2 is configured to generate the triggering voltage for igniting GDT3. All electrodes within the gas discharge tube GDT3 share a common plasma.

FIG. 8 shows a protection circuit 100 according to an embodiment of the invention, which builds on the protection circuit 100 shown in FIG. 3. Same elements in FIG. 3 (and FIG. 4-7) and FIG. 8 share the same reference signs and function likewise. The protection circuit 100 of FIG. 8 includes the at least one inductor Ll of the separation circuit 130, and the TVS in the secondary protection circuit 200. It also includes the at least one inductor L2 in the triggering circuit 140.

The primary protection circuit 150 shown in FIG. 8 includes two (parallel connected) three- terminal gas discharge tubes, namely GDT1 and GDT2, which may effectively function similar to a four-terminal gas discharge tube. That is, the protection circuit 100 of FIG. 8 may be seen as an alternative to the protection circuit 100 of FIG. 7. A first terminal of GDT1 is electrically connected to the first terminal of GDT2 and to a first pole Pl of the primary terminal. A second terminal of GDT1 is electrically connected to second terminal of GDT2 and to a second pole P2 of the primary terminal. A third terminal of GDT2 is electrically connected to ground (P3). The inductor L2 of the triggering circuit 140 is electrically connected between a third terminal of GDT1 and the first terminal of GDT1. The inductor L2 is configured to generate the triggering voltage for igniting GDT1 and GDT2.

In each protection circuit 100 of FIG. 3-8, the primary protection circuit 150 is exemplarily shown to comprise two capacitors Cl and C2. The capacitor Cl is electrically connected between the first pole Pl of the primary terminal and ground, i.e. P3, and the capacitor C2 is electrically connected between the second pole P2 of the primary terminal and ground. The two capacitors Cl and C2 are configured to prevent triggering of the primary protection circuit 150, in particular to prevent ignition of the two three-terminal gas discharge tubes GDT1 and GDT2 (in FIG. 3-6 and FIG. 8) or the four- terminal gas discharge tube GDT3 (in FIG. 7), e.g. when a test signal is applied to the primary terminal.

Further, each protection circuit 100 of FIG. 4-8 is exemplarily shown to comprise at least one switching element Ql, which is arranged in an electrical path between the first terminal and the second terminal. In particular, Ql may be arranged between the primary protection circuit 150 and the secondary terminal. After a lapse of a first time period, which starts with the triggering of the primary protection circuit 150 by the triggering circuit 140, the switching element Ql may be configured to interrupt the electrical path for a second time period. The protection circuit 100 may further comprise a control circuit 170. After lapse of the first time period, the control circuit 170 may be responsible and configured to control the switching element Ql, in order to interrupt the electrical path for the second time period.

Further, each protection circuit 100 of FIG. 4-8 is exemplarily shown to comprise a measurement circuit MC with at least one measurement element, such as a shunt resistor Rs. MC is arranged in an electrical path between the first terminal and second terminal. In particular, MC is arranged between the primary protection circuit 150 and the second terminal. MC may be configured to measure a current caused by the primary protection circuit 150, when it is triggered by the triggering circuit 140. The control circuit 170 may be configured to determine, on the basis of the current measured by MC, the time, at which the primary protection circuit 150 is triggered by the triggering circuit 140.

FIG. 9 shows an electronic circuit arrangement 900 according to an embodiment of the invention. The electronic circuit arrangement 900 comprises the protection circuit 100 as described above, i.e. as in any one of FIG. l-FIG. 8, and comprises the electronic circuit 110 to be protected by the protection circuit 100 against a transient current, transient voltage and/or transient electrical energy. In particular, the protection circuit 100 is electrically connected to an output (Outl, Out2) of the electronic circuit 110. The electronic circuit 110 may be electrically supplied with electrical energy by an electrical energy source 160, which may be electrically connected to an input (Inl, In2) of the electronic circuit 110. The electronic circuit 110 may comprise various electronic sub-circuits 180 that are to be protected. Notably, as exemplarily shown in FIG. 9, the switching element Ql and the control circuit 170 - which were described above with respect to being included in the protection circuit 100 in FIG. 4-8 - may alternatively be included in the electronic circuit 110. Thus, after the lapse of the first time period, a control circuit 170 of the electronic circuit 110 may in this case be configured to control a switching element Ql, which is included in the electronic circuit 110, in order to interrupt the electrical path for the second time period. Alternatively, it may be configured to control the electrical energy source 160 to stop supplying electrical energy to Inl, In2 of the electronic circuit 110 for the second time period.

FIG. 10 shows a method 1000 according to an embodiment of the invention. The method 1000 is specifically a method 1000 of providing protection for an electronic circuit 110 against transient current, transient voltage or transient electrical energy using a protection circuit 100 as described above, i.e. any one of FIG. 1-9. The method comprises: a step of triggering 1002, by the triggering circuit 140, the primary protection circuit 150 on the basis of a current, voltage and/or an electrical energy at the separation circuit 130, when a transient current, transient voltage or transient electrical energy is applied 1001 to the primary terminal.

The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word“comprising” does not exclude other elements or steps and the indefinite article“a” or“an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1 Protection circuit (100) configured to protect an electronic circuit (110) against transient current, transient voltage or transient electrical energy,

wherein the protection circuit (100) comprises:

a separation circuit (130) arranged between a primary terminal and a secondary terminal;

a primary protection circuit (150) arranged between the primary terminal and the separation circuit (130); and

a triggering circuit (140) coupled with the separation circuit (130) and configured to trigger the primary protection circuit (150) on the basis of a current, voltage and/or an electrical energy at the separation circuit (130), when a transient current, transient voltage or transient electrical energy is applied to the primary terminal.

2 Protection circuit (100) according to claim 1,

wherein the separation circuit (130) comprises at least a first inductor (Ll).

3 Protection circuit according to claim 1 or 2, further comprising a secondary protection circuit (200),

wherein the secondary protection circuit (200) comprises at least one voltage limiting device cascaded to the separation circuit (130).

4 Protection circuit (100) according to claim 3,

- wherein the at least one voltage limiting device is configured to generate a current flowing through the separation circuit (130), in particular the at least one first inductor (Ll) of the separation circuit (130), when the transient current, transient voltage or transient electrical energy is applied to the primary terminal.

5 Protection circuit (100) according to claim 3 or 4,

wherein the at least one voltage limiting device comprises at least one of the following: transient-voltage-suppression diode (TVS), a metal oxide varistor, thyristor, a triac, a capacitor for limiting the voltage at the secondary terminal, in particular between two power rails (Sl, S2) connected to the secondary terminal.

6. Protection circuit (100) according to any one of claims 2 to 4, wherein the triggering circuit (140) comprises at least one second inductor (L2) coupled to the at least one first inductor (Ll); and

wherein as a result of a current flowing through the first inductor (Ll) when the transient current, transient voltage or transient electrical energy is applied to the primary terminal, the second inductor (L2) is configured to generate a triggering voltage for triggering the primary protection circuit (150) to provide protection against the transient current, transient voltage or transient electrical energy.

7. Protection circuit (100) according to claim 6,

wherein the at least one first inductor (Ll) forms a primary winding of a transformer and the at least one second inductor (L2) forms a secondary winding of the transformer.

8. Protection circuit (100) according to claim 6 or 7,

wherein the second inductor (L2) has more windings compared to the first inductor (Ll).

9. Protection circuit (100) according to any one of the previous claims,

wherein the primary protection circuit (150) comprises at least one gas discharge tube (GDT1, GDT2, GDT) at the primary terminal; and

wherein on the basis of the current, voltage and/or an electrical energy at the separation circuit (130) when the transient current, transient voltage or transient electrical energy is applied to the primary terminal, the triggering circuit (140) is configured to trigger the primary protection circuit (150) by igniting the at least one gas discharge tube (GDT1, GDT2, GDT);

in particular wherein the at least one second inductor (L2) of the triggering circuit (140) is configured to generate the triggering voltage for igniting the at least one gas discharge tube (GDT1, GDT2, GDT).

10. Protection circuit (100) according to any one of claims 6 to 9, wherein the primary protection circuit (150) comprises two three-terminal gas discharge tubes (GDT1, GDT2) with a common plasma in each gas discharge tube, wherein a first terminal of a first three-terminal gas discharge tube (GDT1) is electrically connected to a first pole (Pl) of the primary terminal, a first terminal of a second three-terminal gas discharge tube (GDT2) is electrically connected to a second pole (P2) of the primary terminal, a second terminal of the first three-terminal gas discharge tube (GDT1) is electrically connected to a second terminal of the second three-terminal gas discharge tube (GDT2), and

a third terminal of the first and second three-terminal gas discharge tube (GDT1, GDT2) is electrically connected to ground;

wherein the second inductor (L2) of the triggering circuit (140) is electrically connected between ground and the node between the two three-terminal gas discharge tubes (GDT1, GDT2); and

wherein the second inductor (L2) of the triggering circuit (140) is configured to generate the triggering voltage for igniting the two three-terminal gas discharge tubes (GDT1, GDT2).

11. Protection circuit (100) according to any one of claims 6 to 9, wherein the primary protection circuit (150) comprises two three-terminal gas discharge tubes (GDT1, GDT2) with a common plasma in each gas discharge tube, wherein

- a first terminal of a first three-terminal gas discharge tube (GDT1) is electrically connected to a first pole (Pl) of the primary terminal, a first terminal of a second three-terminal gas discharge tube (GDT2) is electrically connected to a second pole (P2) of the primary terminal, the second inductor (L2) of the triggering circuit (140) is electrically connected between a second terminal of the first three-terminal gas discharge tube (GDT1) and a second terminal of the second three-terminal gas discharge tube (GDT2),

a third terminal of the first and second three-terminal gas discharge tube (GDT1, GDT2) is electrically connected to ground; and

- wherein the second inductor (L2) of the triggering circuit (140) is configured to generate the triggering voltage for igniting the two three-terminal gas discharge tubes (GDT1, GDT2).

12. Protection circuit (100) according to claim 11,

wherein the primary protection circuit (150) comprises a capacitor (C3) that is electrical connected between the second terminal of the first three-terminal gas discharge tube (GTD1) and ground; and

wherein the capacitor (C3) is configured to support ignition of the two three-terminal gas discharge tubes (GDT1, GDT2) by the second inductor (L2) of the triggering circuit (140).

13. Protection circuit (100) according to any one of claims 6 to 9, wherein the primary protection circuit (150) comprises a four- terminal gas discharge tube (GDT3), wherein

a first terminal of the four-terminal gas discharge tube (GDT3) is electrically connected to a first pole (Pl) of the primary terminal,

a second terminal of the four-terminal gas discharge tube (GDT3) is electrically connected to a second pole (P2) of the primary terminal,

a third terminal of the four-terminal gas discharge tube (GDT3) is electrically connected to ground, and

the second inductor (L2) of the triggering circuit (140) is electrically connected between a fourth terminal of the four-terminal gas discharge tube (GDT3) and ground;

wherein the second inductor (L2) of the triggering circuit (140) is configured to generate the triggering voltage for igniting the four-terminal gas discharge tube (GDT3).

14. Protection circuit (100) according to any one of the previous claims,

wherein the primary protection circuit comprises two capacitors (Cl, C2);

wherein a first capacitor (Cl) is electrically connected between the first pole (Pl) of the primary terminal and ground and a second capacitor (C2) is electrically connected between the second pole (P2) of the primary terminal and ground; and wherein the two capacitors (Cl, C2) are configured to prevent triggering of the primary protection circuit (150), in particular to prevent ignition of the two three- terminal gas discharge tubes (GDT1, GDT2) or the four- terminal gas discharge tube (GDT3), when a test signal is applied to the primary terminal.

15. Protection circuit (lOO)according to any one of the previous claims, wherein the protection circuit (100) comprises at least one switching element (Ql) arranged in an electrical path between the first terminal and second terminal, in particular between the primary protection circuit (150) and the second terminal;

wherein after lapse of a first time period, which starts with the triggering of the primary protection circuit (150) by the triggering circuit (140), the switching element (Ql) is configured to interrupt the electrical path for a second time period.

16. Protection circuit (100) according to claim 15, wherein the protection circuit (100) comprises a control circuit (170),

wherein after lapse of the first time period the control circuit (170) is configured to control the switching element (Ql) to interrupt the electrical path for the second time period.

17. Protection circuit (100) according to any one of the previous claims, wherein the protection circuit (100) comprises a measurement circuit (MC) with at least one measurement element, such as a shunt resistor (Rs), arranged in an electrical path between the first terminal and second terminal, in particular between the primary protection circuit (150) and the second terminal;

wherein the measurement circuit (MC) is configured to measure a current caused by the primary protection circuit (150) when triggered by the triggering circuit (140).

18. Protection circuit (100) according to claim 17, wherein the control circuit (170) is configured to determine on the basis of the current measured by the measurement circuit (MC) the time at which the primary protection circuit (150) is triggered by the triggering circuit (140).

19. Electronic circuit arrangement comprising

- a protection circuit ( 100) according to any one of the previous claims, and

an electronic circuit (110) to be protected by the protection circuit (100) against a transient current, transient voltage or transient electrical energy, wherein the protection circuit (100) is electrically connected to the output (Outl, Out2) of the electronic circuit (110),

wherein the electronic circuit (110) may be electrically supplied with electrical energy by an electrical energy source (160) which may be electrically connected to the input (Inl, In2) of the electronic circuit (110).

20. Electronic circuit arrangement according to claim 19, wherein

the electronic circuit (110) comprises a control circuit (170),

wherein after lapse of the first time period the control circuit (170) is configured - to control the switching element (Ql) of the protection circuit to interrupt the electrical path for the second time period, or

to control the electrical energy source (160) to stop supplying electrical energy to the input (Inl, In2) of the electronic circuit (110) for the second time period.

21. Method of providing protection for an electronic circuit (110) against transient current, transient voltage or transient electrical energy using a protection circuit (100) according to any one of claims 1 to 18, wherein the method comprises the step of

- triggering by the triggering circuit (140) the primary protection circuit (150) on the basis of a current, voltage and/or an electrical energy at the separation circuit (130) when a transient current, transient voltage or transient electrical energy is applied to the primary terminal.