EP2138923A1 - System, method and electronic switch for at least one electronic switch unit - Google Patents

Abstract

The circuit (200) has a unit (220) for current detection, where the circuit is arranged to deliver a signal, when the detected current lies under a pre-determined threshold value. The circuit is connected with a negative supply connector (115) of an electronic switching unit (110) via a connector (210). The circuit detects current flowing between the connector (210) and another connector (215), in one of the conditions, and detects no current flowing between the connectors, in the other condition. A current limitation unit is provided for protection of the current detection unit. Independent claims are also included for the following: (1) a method for electronic switching of switching units (2) an electronic system comprising an electronic control unit.

Description

INTRODUCTION

The present invention relates to a system, a method and an electronic circuit for at least one electronic circuit unit.

STATE OF THE ART

Electronic circuit units 110 are used in a variety of fields, e.g. for driving, controlling, switching or the like of electrical devices 130.

For example, such an electronic circuit unit 110 may represent a driver element 110 having an output 111 for driving electrical loads 130, the driver element 110 being e.g. is connected via a positive supply terminal 114 to a supply voltage applied to line 170 and to a negative supply terminal 115 via an outgoing supply line 155 having a lower potential 140, e.g. Mass, connected.

In electronic circuit units 110, the case often occurs that resistors 120 between outputs 111 the circuit unit 110 and the negative supply terminal 115 exist, which resistors may represent, for example, discharge circuits or other protection circuits. If during operation of the circuit 100 there is an interruption 160 of the outgoing supply line 155, such as due to a neutral break, parasitic current flow from the negative supply terminal 115 via the line 150, the resistor 120 and the electrical load 130 to the ground 140 come. Depending on the situation, this can lead to the potential at the negative supply connection 155 being increased by several volts above ground, so that undefined and unstable states can occur at the output 111 of the driver element 110. This can be problematic in particular if the voltage potential at the output 111 is raised so far above ground even when the "Low" switched state, so that successor devices can no longer reliably detect the "Low" state.

DESCRIPTION OF THE INVENTION

The invention is based on the object to increase the error safety in an interruption of a supply line for the underlying potential.

This object is achieved by an electronic circuit for at least one electronic circuit unit, wherein the electronic circuit via a first terminal with a negative Supply terminal of the at least one electronic circuit unit and a second terminal is connected to an outgoing supply line, wherein the electronic circuit comprises means for current detection, and the electronic circuit outputs a signal when the detected current is below a predetermined threshold, and wherein the electronic circuit is switchable to a first state and a second state, wherein the electronic circuit in the second state detects a current flowing between the first terminal and the second terminal current, and wherein the electrical circuit in the first state does not flow between the first terminal and the second terminal Electricity recorded.

This object is further achieved by a method for an electronic circuit which is connected via a first terminal to a negative supply terminal of the at least one electronic circuit unit and via a second terminal to an outgoing supply line, and wherein the electronic circuit in a first state and a the second state is switchable, the method comprising: switching the electronic circuit to a second state and detecting a current flowing between the first terminal and the terminal during the second state; and outputting a signal when the sensed current is below a predeterminable threshold; and wherein in the first state, no current flowing between the first terminal and the second terminal is detected.

This object is further achieved by an electronic system comprising the above-described electronic circuit and at least one electronic circuit unit, wherein the negative supply terminal of each of the at least one electronic circuit unit is connected to the first terminal of the electronic circuit; and wherein the system comprises an electronic control unit connected to the electronic circuit and configured to switch the electronic circuit to the first state and the second state, respectively.

The outgoing supply line may, for example, be connected to a ground potential, and the at least one electronic circuit unit may be supplied with power with a positive supply connection from a feeding supply line.

For example, the electronic circuit unit may represent a driver element having at least one output for driving electrical loads, wherein this driver element may have at least one input for driving the at least one output. The outputs can represent, for example, semiconductor outputs.

The electronic circuit may be positioned at any suitable position between the outgoing supply line and the negative supply terminal of the at least one electronic circuit unit.

The electronic circuit comprises means for current detection, wherein the circuit may have an output for outputting the signal when the current detected by the means for current detection is below a predefined threshold value. For example, the signal may be set to a certain voltage level if the detected current is below the predefined threshold.

Furthermore, the electronic circuit is switchable to a first state and a second state, wherein in the second state, a current between the first terminal and the second terminal is detected. Thus, it can be determined in the second state whether a current flowing from the negative supply connection of the at least one electronic circuit unit via the electronic circuit to the outgoing supply line is below the predefined threshold value.

The predefined threshold value may, for example, be selected such that it lies below a quiescent current required by the at least one electrical circuit unit. If, for example, the outgoing supply line is interrupted, eg by a neutral conductor break or the like, then a current flowing via the negative supply connection no longer flows via the electronic circuit unit, since the second connection of the electrical circuit is connected only to the now interrupted outgoing supply line and thus this circuit is interrupted. At the same time falls through this interruption of the current detected by the means for current detection below the predefined threshold value, this being signaled by the corresponding signal at the output. For example, this signal can be represented by a first voltage level at the output. Thus, in the second state of the electronic circuit, an interruption of the outgoing supply line can be detected. This interruption can still be detected even if due to the interrupted outgoing supply line, a current flows from the negative supply terminal of the at least one circuit unit via an additional path to ground. For example, these additional paths can be effected by additional circuits at the at least one output of the electronic switching unit, such as discharge circuits for capacitive loads or surge protective circuits on semiconductor outputs or the like.

If there is no interruption of the outgoing supply line, the current coming from the negative supply connection flows regularly via the electronic circuit to the outgoing supply line, this outgoing current being above the predefined threshold value. This exceeding of the predefined threshold value can be signaled for example by the electronic circuit unit by a further signal, such as a second voltage level at the output.

When the electronic circuit is switched to the first state, no current flowing between the first terminal and the second terminal is detected. For example, for this purpose, the means for current detection can be deactivated or the electronic circuit can have switching means, which in the first state diverts a current coming from the first terminal via a different path, which does not lead through the means for current detection, to the second terminal. Thus, in the first state, exposure of the current sensing means to the flowing current can be reduced or avoided, e.g. one of the means for current detection caused additional potential difference between the second terminal and the first terminal, whereby a reliable operation of the electronic circuit unit in the first state can be achieved.

For example, the electrical circuit can normally be operated in the first state and at certain intervals, e.g. periodic intervals, to be switched to the second state. This switching to the second state may, for example, be for a short period of time in the millisecond range, e.g. within a range of 1 ms - 10ms, although this range may differ

After this short time period, the circuit is switched back to the first state, so that a normal operation without affecting the means for current detection can be ensured. For example, the circuit may periodically check the discharged current for a short time each time from the first state the second state are switched, and after checking to operate the electrical load directly back to the first state.

Thus, it can be checked at these specific intervals during the second state, whether a flowing from the electronic circuit via the negative supply connection flows properly through the outgoing supply line, or if there is an interruption of the outgoing supply line.

The electrical circuit may for example have an input with which it can be switched to the first or second state, this control being e.g. from a control unit, e.g. a microcontroller may be performed, or the circuit may have its own control unit for periodically switching to the second state.

Thus, an interruption of the outgoing supply line can be reliably detected, even if additional niederimpedante circuits between the internal ground and outputs or current paths between the internal ground and outputs are provided, thus enabling safe outputs of the electronic circuit unit.

An embodiment of the invention provides that the electronic circuit comprises overcurrent protection means for protecting the means for current detection.

These overcurrent protection means may be arranged to limit a current flowing through the means for current detection, which is to be detected. Thus, it can be avoided that the means for current detection are disturbed and / or damaged by an overcurrent. Furthermore, the electronic circuit can also have voltage limiting means, which can be placed, for example, between the first terminal and the second terminal, so that, for example, suddenly occurring voltage peaks can be limited. The means for limiting the voltage and the means for limiting the current can also be used in combination, for example.

An embodiment of the invention provides that the overcurrent protection means comprise at least one placed between the negative supply terminal and the supply line transistor, which is driven by the current to be detected.

For example, the current to be detected can be passed through a resistor, wherein the voltage drop across the resistor drives the at least one transistor. If an excessively high current flows, the at least one transistor can be driven by the voltage dropping across the resistor, so that an additional way of directly diverting the overcurrent between the first and the second terminal is switched without the current detection means flow. Thus, the means for current detection can be protected from occurring overcurrents.

An embodiment of the invention provides that the means for current detection have an input which is placed electrically between the first terminal and the second terminal, and the electronic circuit comprises switching means which short-circuit the input in the first state.

These switching means are configured, for example, to short-circuit the input of the means for current detection in the first state, so that in the first state a current coming via the first connection can flow to the second connection via the switching means, without being detected by the means for current detection.

In contrast, in the second state, the switching means are opened, for example, so that a current coming from the first connection can flow via the input through the means for current detection. The means for current detection may further comprise an output at which, for example, a signal proportional to the detected current is output.

The switching means may, for example, be electromechanical switching means, e.g. at least one relay or the like, or semiconductor switching means such as at least one transistor or the like.

The switching means can be driven, for example via an input, so that the electronic circuit can be placed in the first or second state of this input. The electronic circuit can also have internal control means connected to the input for controlling the switching means.

The means for current detection, for example, comprise an optocoupler, wherein the current to be detected flows on the input side through an input of the optocoupler. Accordingly, the optocoupler outputs an output current as a function of the input-side current on the output side.

By using an opto-coupler as means for current detection, a galvanic separation of the current flowing on the output side from the current to be detected on the input side is simultaneously achieved.

An embodiment of the invention provides that the means for current detection have an output for outputting the detected current, and an input of a threshold detection unit is electrically connected to this output, wherein the threshold detection unit has a signal output for outputting the signal when the detected current is below the predetermined one Threshold is.

By way of example, the threshold value detector may comprise a transistor which switches on when the current detected by the current detection means exceeds the predefinable threshold value and which disconnects when the detected current falls below the predefined threshold value. Thus, for example, falls below the threshold value, a logically high level at the output of the threshold value can be output and when the threshold is exceeded, a logically lower Levels are output. However, the transistor can also be connected, for example, so that a logically high level is output when the threshold value is exceeded. The predefinable threshold value can be adjustable, for example, at the threshold value detector.

An embodiment of the invention provides that the electronic circuit comprises means for galvanic isolation, which decouple the output of the threshold value detection unit galvanically from the negative supply terminal and the supply line.

For example, the means for current detection can be realized as an opto-coupler, or another optocoupler can be placed between the means for current detection and the threshold detector.

An embodiment of the invention provides that the means for current detection comprise an optocoupler.

An embodiment of the invention provides that the electronic circuit comprises an input for driving in the first state or the second state.

This input can, for example, be galvanically decoupled from the negative supply connection and the supply line, wherein, for example, an optocoupler can be used for this galvanic decoupling.

Thus, the electronic circuit can be switched by this input in the first and the second state.

For example, this input, as well as the output of the threshold detector may be connected to an electronic control unit.

An embodiment of the invention provides that the electronic control unit is set up to switch the electronic circuit from the first state to the second state at predeterminable intervals, each for a short period of time.

In the second state of the electronic circuit, a signal is output when the detected current is above the predetermined threshold. This signal can be detected by the control unit and can be used for further signal processing.

Thus, e.g. be checked at periodic intervals by switching to the second state, whether the effluent from the at least one electronic circuit unit current flows properly through the electronic circuit and thus on the outgoing supply line.

An embodiment of the invention provides that the electronic control unit is set up to interrupt the power supply to the at least one electronic circuit unit when the electronic circuit is in the second state and outputs the signal indicating that the detected current is below the predefinable threshold value lies.

Thus, in the event of a detected line interruption, the at least one electronic circuit unit can be switched off. Hereby, an undefined state at the at least one output of the electronic circuit unit can be avoided. For example, the control may comprise a power transistor, but may also include other - e.g. electromechanical - switching means include.

An embodiment of the invention provides that the electronic control unit is adapted to interrupt the power supply to the at least one electronic circuit unit when the electronic circuit is in the first state and the signal is not received by the electronic circuit, which indicates that the detected current is below the predetermined threshold.

Thus, when the electronic circuit is switched to the first state and the current flowing between the first terminal and the second terminal is not detected, the control unit can check the correct function of the electronic circuit, since in this case the electronic circuit at the output falls below the threshold value would signal if the current detection and evaluation in the electronic circuit is working correctly, as previously explained in detail. If the undershooting of the current threshold value is not signaled at the output in the first state, then the control unit can likewise switch off the power supply to the electronic switching unit by correspondingly switching the control element.

Thus, the present invention allows reliable detection of outgoing supply line breakage even when additional low impedance circuits connected to the outputs are present. Furthermore, the correct operation of the circuit can be checked by a self-test during the first state.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be explained in more detail below with reference to exemplary embodiments showing drawings.

Fig. 1:

Eine schematische Darstellung eines Systems gemäß dem Stand der Technik;

Fig. 2:

Eine schematische Darstellung einer ersten beispielhaften Ausführungsform der vorliegenden Erfindung;

Fig. 3:

Eine schematische Darstellung einer zweiten beispielhaften Ausführungsform der vorliegenden Erfindung;

Fig. 4:

Eine schematische Darstellung eines Flussdiagramms eines beispielhaften Verfahrens der vorliegenden Erfindung;

Fig. 5:

Eine schematische Darstellung einer dritten beispielhaften Ausführungsform der vorliegenden Erfindung; und

Fig. 6:

Eine schematische Darstellung einer beispielhaften Ausführungsform eines Systems der vorliegenden Erfindung.

Showing:

Fig. 1:

A schematic representation of a system according to the prior art;

Fig. 2:

A schematic representation of a first exemplary embodiment of the present invention;

3:

A schematic representation of a second exemplary embodiment of the present invention;

4:

A schematic representation of a flowchart of an exemplary method of the present invention;

Fig. 5:

A schematic representation of a third exemplary embodiment of the present invention; and

Fig. 6:

A schematic representation of an exemplary embodiment of a system of the present invention.

FIG. 2 shows a schematic representation of a first exemplary embodiment of the present invention. The first exemplary embodiment will be described below together with the in Fig. 4 illustrated schematic representation of a flowchart of an exemplary method of the present invention.

The electronic circuit 200 according to the first exemplary embodiment is connected via a first connection 210 to the negative supply connection 115 of an electronic circuit unit 110 and via a second connection 215 to an outgoing supply line 155, the outgoing supply line 155 being connected to a ground potential 140, for example. which represents a deeper supply potential. The electronic circuit 200 may in this case be positioned at any suitable position between the outgoing supply line 155 and the negative supply connection 115. In Fig. 2 For example, the electronic circuit 200 is connected via the line 150 to the negative supply terminal 115. The circuit unit 110 is further connected via a positive supply connection 114 to a live line 170, which represents a higher supply potential.

The electronic circuit 200 comprises means 220 for current detection, wherein the circuit 200 outputs a signal via the output 205 when the current detected by the means 220 for current detection below a predefined Threshold is. For example, the signal at output 205 may be set to a certain voltage level when the detected current is below the predefined threshold.

Furthermore, the electronic circuit 200 is switchable to a first state and a second state, wherein in the second state, a current between the first terminal 210 and the second terminal 215 is detected. Thus, it can be determined in the second state whether a current flowing from the negative supply connection 115 of the electronic circuit unit 110 via the electronic circuit 200 to the outgoing supply line 155 is above the predefined threshold value.

The predefined threshold value can be selected, for example, such that it lies below a quiescent current required by the electrical circuit unit 110. If, for example, the outgoing supply line 155 is interrupted, eg by a neutral conductor break or the like, a current flowing via the negative supply connection 115 no longer flows via the electronic circuit unit 110, so that the current detected by the means 220 for current detection falls below the predefined threshold value falls and this is signaled by the corresponding signal at the output 205. For example, this signal may represent a certain first voltage level at the output 205. Thus, in the second state of the electronic circuit 200, an interruption of the outgoing supply line 155 can be detected.

This interruption can still be determined even if, due to the interrupted outgoing supply line 155, a current flows from the negative supply connection 115 of the at least one circuit unit 110 via an additional path to ground 140. For example, these additional paths may be effected by additional circuits at the at least one output of the electronic switching unit, such as e.g. e.g. Discharge circuits for capacitive loads or protective circuits against surge on semiconductor outputs or the like.

If there is no interruption of the outgoing supply line 155, the current coming from the negative supply connection 115 flows regularly via the electronic circuit 200 to the outgoing supply line 155, this outflowing current being above the predefined threshold value. This exceeding of the predefined threshold value can be achieved, for example, by the electronic circuit unit 200 by a further signal, e.g. a second voltage level, be signaled at the output 205.

When the electronic circuit 200 is switched to the first state, no current flowing between the first terminal 210 and the second terminal 215 is detected. For example, for this purpose, the means 220 for current detection can be deactivated, or the electronic circuit 200 can switching means (not in Fig. 2 shown), which in the first state one coming from the terminal 210 current via another Path, which does not lead by the means 220 for current detection, to the second terminal 215 redirects. Thus, in the first state, exposure of the current sensing means 220 to the flowing current may be reduced or avoided, such as an additional potential difference between the second terminal 215 and the first terminal 210 caused by the current sensing means 220, thus providing reliable operation electronic circuit unit 110 can be achieved.

For example, the electrical circuit 200 may normally be operated in the first state and switched to the second state at certain intervals, such as periodic intervals. For example, in starting point 405 of the in Fig. 4 2, the electrical circuit 200 may be assumed to be in the first state, and after a predetermined period of time, the circuit 200 may be switched to the second state (step 410). This switching to the second state can take place, for example, for a short time period in the millisecond range, for example in a range of 1 ms-10 ms, although this range can also deviate therefrom. If it is determined in step 420 that the detected current is below the predetermined threshold, then a step 430 the corresponding signal is output to output 205, as already explained above.

After this short period of time, the circuit is switched back to the first state (step 440), so that normal operation without influencing the means 220 can be ensured for current detection. The method may then jump back to the starting point and be periodically switched to the second state for checking the discharged current.

Thus it can be checked at these specific intervals during the second state, whether a flowing from the electronic circuit 110 via the negative supply port 115 flows properly through the outgoing supply line 155, or if there is an interruption of the outgoing supply line 155.

The electrical circuit 200 may include, for example, an input (in Fig. 2 not shown), with which this can be switched to the first or second state, this control can be performed for example by a microcontroller, or the circuit 200 may have its own control unit for periodically switching to the second state.

Fig. 3 shows a schematic representation of a second exemplary embodiment of the present invention, wherein in this Fig. 3 only the schematic representation of the electronic circuit 300 according to this exemplary embodiment is shown. This electronic circuit 300 may, for example, for the in Fig. 2 shown electronic circuit 200, wherein the explanations and advantages referred to the first exemplary embodiment apply equally to the second exemplary embodiment.

In addition to means 220 'for current detection, which those of the previously described means 220 for current detection Fig. 2 may correspond, the electronic circuit 300 comprises switching means 340, which are placed electrically between the first terminal 210 and the second terminal 215. These switching means 340 are configured to short-circuit an input 221, 222 of the means 220 'for current detection in the first state, so that in the first state a current coming via the first connection 210 can flow to the second connection 215, without being detected by the means 220' for current detection to be recorded.

In the second state, on the other hand, the switching means 340 are open, so that a current 210 coming from the first terminal 210 can flow via the input 221, 222 through the means 220 'for current detection, as shown by way of example in FIG Fig. 3 shown. The means 220 'for current detection have an output 223 at which, for example, a signal proportional to the detected current is output. The switching means 340 may be, for example, electromechanical switching means, such as at least one relay or the like, or semiconductor switching means such as at least one transistor or the like.

The switching means 340 can be controlled via an input 341, this input 341 can be connected to an input 350 of the electronic circuit 300, so that the electronic circuit 300 via this input 350 in the first and second state can be offset. The electronic circuit 300 may also have internal control means connected to the input 341 for driving the switching means 340 (not in FIG Fig. 3 shown), wherein these internal control means can also be controlled via the external input 350.

Furthermore, the electronic circuit 300 may include overcurrent protection means (not in US Pat Fig. 3 shown) which are arranged to; to limit a current flowing through the input 221,222 of the means 220 'for current detection current. Thus, it can be avoided that the means 220 'for current detection by an overcurrent disturbed and / or damaged. Furthermore, the electronic circuit 300 may also have voltage limiting means (not in FIG Fig. 3 shown), which may be placed, for example, between the first terminal 210 and the second terminal 215, so that, for example, suddenly occurring voltage peaks can be limited. The means for limiting the voltage and the means for limiting the current can also be used in combination, for example.

Furthermore, the electronic circuit 300 comprises a threshold detector 330, which is connected to the output 223 of the means 220 'for current detection and, for example, outputs a specific signal at the output 205 if the detected current is below the predefinable threshold value. At the threshold value detector 330, for example, the predefinable threshold value can be set, so that the predefinable threshold value is adapted to the boundary conditions of the at least one electronic Switching unit 110 and the overall circuit can be adjusted.

Further, the electronic circuit 300 may include means for electrical isolation between the input 221, 222 of the current sensing means 220 'and the output 205. Thus, galvanic decoupling from the signal output 205 to the circuit of the current to be detected, i. to the first port 210 and second port 215.

Furthermore, means for galvanic isolation between the signal input 350 and the input 341 of the switching means 340 can be placed, so that here too the signal input 350 can be galvanically separated from the circuit of the current to be detected.

The means for galvanic separation can e.g. comprise an isolation transformer or e.g. an optocoupler or other suitable means.

Fig. 5 shows a schematic representation of a third exemplary embodiment of the present invention.

This third exemplary embodiment is based on the above-explained second exemplary embodiment, so that the aforementioned explanations and advantages apply equally to the third embodiment.

The means for current detection 520 comprise an opto-coupler 520, wherein the current to be detected flows on the input side through the terminals 521 and 522 and accordingly outputs on the output side a current flowing through the terminals 523 and 524 output current, said output side flowing current is galvanically isolated from the input current.

The threshold detector 530 comprises a transistor 535, which turns on when the current detected by the optocoupler 520 exceeds the predefined threshold value, and which disconnects when the current detected by the opto-coupler 520 falls below the predefined threshold value. Thus, when the threshold value is undershot, a logically high level is output at the output 205 and, when the threshold value is exceeded, a logically low level is output at the output 205. However, the transistor 535 can, for example, also be connected such that a logically high level is output when the threshold value is exceeded. The resistor 531 may be adjustable, for example, and e.g. be designed as a potentiometer, so that the predetermined threshold is adjustable. The optional capacitor 515 acts as a high pass and may be e.g. Short-circuit transients to ground. The resistors 532 and 533 are optional components.

The electronic circuit 500 can be switched via the input 550 in the first and second state. This signal input 550 is galvanically isolated from the circuit of the current to be detected via the optocoupler 555. Thus, a complete galvanic Separation of the signal inputs and outputs 205,550 from the circuit of the current to be detected can be achieved.

The optocoupler 555 is connected to the input 541, 542 of the switching means 540, the switching means 540 comprising a transistor 545. If a logic high level is applied to the input 550, the optocoupler 555 outputs a corresponding signal and the transistor 545 is turned on. In this case, the electronic circuit 500 is in the first state, as it is short-circuited on the input side between the electrical nodes 568 and 569 by the transistor 545 of the switching means 540. Thus, in the first state, current from the terminals 210 and 215 does not flow through the current sensing means 520, but is passed through the shorted nodes 568 and 569 without flowing into the measuring optocoupler 520. The input of the measuring optocoupler 520 is thus short-circuited by the switching means 540 during the first state.

If a logically low level is present at the input 550, the transistor 545 is blocked by the optocoupler 555 and the electronic circuit 500 is in the second state. Thus, in the second state, the input of the measuring optocoupler 520 is not short-circuited and a current coming from the terminals 210 and 215 can be detected by the measuring optocoupler.

Furthermore, the electronic circuit 500 comprises current-limiting means 560. For this purpose, a resistor 562 in series with the input 521.522 of the Meßoptokopplers in which the voltage drop across the resistor 562 drives the transistor 565. If too high a current flows through the input 521, 522 of the measuring optocoupler in the second state, then the transistor 565 is triggered by the voltage dropping via resistor 562 and the overcurrent can flow directly from node 569 to node 568, without passing through the input of the measuring optocoupler 520 flow. Thus, the measuring optocoupler 520 can be protected from occurring overcurrents. The resistor 561 may be used for operating point adjustment, wherein the values for the resistors 561 and 562 may be selected in response to an overcurrent threshold at which the transistor 565 is to turn on. The capacitor 563 is an optional component.

Further, the electronic circuit 500 may include optional overvoltage protection means 570, which may include, for example, at least one in series diode. If too high a voltage is present between the first terminal 210 and the second terminal 215, which could jeopardize the measuring optocoupler 520, then the at least diode starts to conduct. Thus, a further protection of the measuring optocoupler 520 can be achieved, in particular against occurring surge voltages, which can occur, for example, in lightning or the like. The optional low resistance 514 may also provide additional protection against overvoltage, but the measurement of the circuit is not affected because of the low resistance of the resistor 514.

Optional input capacitors 511 and 512, as well as optional resistors 543, 544, 557, and optional capacitor 546 may be sized and dimensioned according to the specific requirements of electronic circuit 500.

Thus, in normal operation, a logic high level may be applied to the input 550 such that the electronic circuit 500 is in the first state and the switching means 540 short-circuit the measurement input 521, 522 of the measuring optocoupler 520. Furthermore, it can be tested in this first state whether the detection of the current threshold value undershoot functions, because with short-circuited measuring optocoupler 520, the undershooting of the predetermined threshold value at the output 205 must be signaled, e.g. by a logic high level. Thus, the function of the threshold detection in the first state by monitoring the signal at the output 205 done.

As previously described and also exemplified in connection with flowchart in FIG Fig. 4 1, the electronic circuit 500 may be switched to the second state at certain intervals, wherein it is checked in the second state whether the current detected by the measuring optocoupler 520 exceeds the predetermined threshold value.

Fig. 6 FIG. 12 shows a schematic representation of an exemplary embodiment of a system 600 of the present invention.

The system 600 includes an electronic circuit 200 'according to the present invention, which is connected to the first terminal 210 in the negative supply terminal 115 of the electronic circuit unit 110 and is connected to the second terminal 215 with the outgoing supply line 155.

The electronic circuit 200 'may be any of those previously described with reference to the FIGS. 2, 3 and 5 illustrated embodiments of electronic circuit 200, 300 and 500 correspond to or modifications thereof, the above explanations and advantages apply equally to the electronic circuit 200 '.

Thus, the electronic circuit 200 'outputs a corresponding signal at output 205 when the detected current is below a predefinable threshold. Furthermore, the electronic circuit 200 'is switchable via the input 350 into a first state and into a second state, wherein the electronic circuit 200' in the second state detects a current flowing between the first terminal 210 and the second terminal 215 current, and wherein the electrical circuit 200 'detected in the first state no current flowing between the first terminal 210 and the second terminal 215 current.

The system 600 further includes a control unit 610, which may be, for example, a microcontroller or the like. The control unit 610 is connected to the signal output 205 and the input 3505 of the electronic circuit 200 'and thus can the electronic circuit 200' via the input 350 in the first state or the second state switch. In the control unit 610, for example, with respect to Fig. 4 illustrated exemplary method according to the present invention be implemented.

As explained above, for example, the electronic circuit 200 'can be switched to the second state at certain time intervals, so that in this second state a signal is output at the output 205 when the detected current is above the predefinable threshold value. This signal is detected by the control unit 610 and can be used for further signal processing.

If e.g. in the second state, detecting a current below the threshold, i. For example, if there is an interruption of the outgoing supply line 155, the control unit 610 can interrupt the power supply to the electronic circuit unit 110 via the control element 620. Thus, an undefined state at the at least one output 111 of the electronic circuit unit 110 can be avoided. For example, the control may comprise a power transistor, but may also include other - e.g. electromechanical - switching means include.

Further, when the electronic circuit 200 'is switched to the first state and the current flowing between the terminals 210 and 215 is not detected, the control unit can check the correct operation of the electronic circuit 200' In this case, the electronic circuit 200 'at the output 205 must signal the falling below the threshold value when the current detection and evaluation in the electronic circuit 200' works correctly, as previously explained in detail. If, in the first state, the undershooting of the current threshold value is not signaled at the output 205, the control unit can also, for example, initiate the power supply to the electronic switching unit 110 by correspondingly switching the control element 620.

Thus, the present invention allows reliable detection of outgoing supply line breakage even when additional low impedance circuits connected to the outputs are present.

Claims (13)

Electronic circuit (200, 200 ', 300, 500) for at least one electronic circuit unit (110), wherein the electronic circuit (200, 200', 300, 500) is connected via a first connection (210) to a negative supply connection (115) of the at least one electronic circuit unit (110) connected to an outgoing supply line (155) via a second terminal (215), the electronic circuit (200,200 ', 300,500) comprising means (220,220', 520) for current detection, and the electronic circuit being adapted to output a signal, when the detected current is below a predetermined threshold, and wherein the electronic circuit (200,200 ', 300,500) is switchable to a first state and a second state, wherein the electronic circuit (200,200', 300,500) in the second state one between the first Detects the current flowing through terminal (210) and the second terminal (215), and wherein the electrical circuit (200, 200 ', 300, 500) in the first state, no current flowing between the first terminal (210) and the second terminal (215) is detected. An electronic circuit according to claim 1, comprising overcurrent protection means (560) for protecting the current sensing means (220, 520). The electronic circuit of claim 2, wherein the overcurrent protection means (560) comprises at least one transistor (565) placed between the negative supply terminal (115) and the outgoing supply line (155), which is driven by the current to be detected. The electronic circuit of any one of claims 1-3, wherein said current sensing means (220 ', 520) has an input (221, 222, 522, 522) placed electrically between said first port (210) and said second port (215) and said electronic port Circuit switching means (340,540), which short-circuit the input (221,222,521,522) in the first state. The electronic circuit of any one of claims 1-4, wherein said current sensing means (220 ', 520) has an output (223,523,524) for outputting the sensed current, and an input of a threshold detector unit (330,530) is electrically connected to said output (223,523,524) , and wherein the threshold detector unit (330, 530) has a signal output (205) for outputting the signal when the detected current is below the predetermined threshold. An electronic circuit according to claim 5, including means (520) for galvanic isolation which galvanically decouple the output of the threshold detector unit from the negative supply terminal (115) and the outgoing utility line (155). An electronic circuit according to claims 1-6, wherein said means (220,220 ', 520) for current sensing comprises an optocoupler (520). An electronic circuit according to any one of claims 1-6, comprising an input (350,550) for driving to the first state and the second state, respectively, said input (350,550) being galvanically decoupled from the negative supply terminal (115) and the outgoing supply line (155) is. Method for an electronic circuit (200, 200 ', 300, 500) which has a first connection (210) with a negative supply connection (115) of the at least one electronic circuit unit (110) and a second connection (215) with an outgoing supply line (155) wherein the electronic circuit (200, 200 ', 300, 500) is switchable to a first state and a second state, the method comprising: Switching the electronic circuit (200, 200 ', 300, 500) to a second state and detecting a current flowing between the first terminal (210) and the terminal (215) during the second state; - Output of a signal when the detected current is below a predetermined threshold value; and wherein in the first state, no current flowing between the first terminal and the second terminal is detected. Electronic system 600, comprising: - An electronic circuit (200,200 ', 300,500) according to any one of claims 1-8; - At least one electronic circuit unit (110), wherein the negative supply terminal (115) of each of the at least one electronic circuit unit (110) to the first terminal (210) of the electronic circuit (200,200 ', 300,500) is connected; an electronic control unit (610) connected to the electronic circuit (200, 200 ', 300, 500) and arranged to switch the electronic circuit (200, 200', 300, 500) to the first state and the second state, respectively. The electronic system of claim 10, wherein the electronic control unit (610) is arranged to switch the electronic circuit (200, 200 ', 300, 500) at predetermined intervals from the first state to the second state for a short period of time. An electronic system according to any one of claims 10-11, wherein the electronic control unit (610) is adapted to supply the power to the at least one electronic circuit unit (110) interrupt when the electronic circuit (200,200 ', 300,500) in the second state and the signal is issued, indicating that the detected current is below the predetermined threshold. The electronic system according to any one of claims 10-12, wherein the electronic control unit 610 is adapted to cut off the power supply to the at least one electronic circuit unit 110 when the electronic circuit 200,200 ', 300,500 is switched to the first state and not the signal from the electronic circuit is received, which indicates that the detected current is below the predetermined threshold.

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