Electronic switching apparatus for controlling loads in a motor vehicle

Abstract

The invention relates to an electronic switching apparatus (10) for controlling loads in a motor vehicle, having - a first switching device (12a) which takes the form of a first transistor and has a control terminal, a first terminal and a second terminal, wherein the first terminal is connected to a supply voltage terminal (26) and the second terminal is connected to a load terminal (28), wherein the first switching device (12a) is designed to provide a supply voltage at the load terminal (28) when switched on, as a result of which a first current flows through the first load; - a second switching device (12b) which takes the form of a second transistor and which has a control terminal, a first terminal and a second terminal, wherein the first terminal is connected to the supply voltage terminal (26) and the second terminal is connected to a load terminal (28), wherein the second switching device is designed to provide the supply voltage at the load terminal (28) when switched on, as a result of which a second current flows through the first load, wherein the first switching device (12a) and the second switching device (12b) are designed such that the second current is greater than the first current; and - a control unit (14) which is designed to transfer the first switching device (12a) and the second switching device (12b) in each case into a switched-on state and a switched-off state by providing a first control signal at the control terminal of the first switching device (12a) and a second control signal at the control terminal of the second switching device (12b).

Description

[0001] Electronic for loads in a

[0002] Motor vehicle

[0003] The present invention relates to an electronic switching device for controlling loads in a motor vehicle.

[0004] Electronic switching devices are generally known from the prior art and described in various embodiments. These are sometimes used in electronic fuses, which serve to interrupt the flow of current to one or all consumers if a fault (e.g., a short circuit) has been detected.

[0005] For example, various electronic switches are described in DE 10 2017 108 872 Al and DE 10 2019 121 685 Al.

[0006] The switching devices known from the prior art offer various advantages. However, no switching devices are known to date that allow a standby mode with reduced energy consumption and, at the same time, an efficient switching mechanism between the standby mode and an active mode.

[0007] Based on the above-mentioned limitations, it is an object of the present invention to provide a switching device that offers a standby mode with reduced energy consumption and at the same time allows an efficient switching mechanism for switching between the standby mode and an active mode.

[0008] To achieve the above-mentioned object, the present invention proposes an electronic switching device for controlling loads in a motor vehicle, comprising a first switching device which is designed as a first transistor and has a control terminal, a first terminal and a second terminal, wherein the first terminal is connected to a supply voltage terminal and the second terminal to a load terminal; wherein the first switching device is designed to provide a supply voltage at the load terminal in a switched-on state, whereby a first current flows through the first load; a second switching device which is designed as a second transistor and has a control terminal, a first terminal and a second terminal, wherein the first terminal is connected to the supply voltage terminal and the second terminal to a load terminal;wherein the second switching device is designed to provide the supply voltage at the load terminal in a switched-on state, whereby a second current flows through the first load; wherein the first switching device and the second switching device are designed such that the second current is greater than the first current; a control unit which is designed to transfer the first switching device and the second switching device, respectively, into a switched-on state and a switched-off state by providing a first control signal at the control terminal of the first switching device and a second control signal at the control terminal of the second switching device;wherein the control unit is further configured to transfer the electronic switching device into a standby mode and into an active mode, wherein in the standby mode the first switching device is switched on and the second switching device is switched off, and in the active mode the first switching device is switched on and the second switching device is also switched on.;

[0009] The first load may have several partial loads, whereby it may be provided that some partial loads remain permanently switched on (i.e. also in standby mode) and some partial loads are switched off in standby mode.

[0010] The present invention allows for a standby mode with reduced power consumption, enabling efficient switching between standby mode and active mode by the control unit. A further advantage of the present invention is that the partial loads that are to be permanently supplied are supplied without interruption, since the first transistor can remain permanently switched on.

[0011] The first transistor and the second transistor can preferably each be embodied as a MOSFET transistor. The first terminal of the first transistor can be a source terminal, while the second terminal of the first transistor can be a drain terminal. Likewise, the first terminal of the second transistor can be a source terminal, while the second terminal of the second transistor can be a drain terminal.

[0012] Preferably, the switching device may comprise a voltage evaluation unit designed to detect a voltage at the first transistor and to generate an output signal as a function of the detected voltage, wherein the voltage evaluation unit is designed to transmit the output signal to the control unit.

[0013] Preferably, the voltage evaluation unit can be designed as a comparator with two input terminals and one output terminal, wherein the first input terminal of the comparator is connected to the second terminal of the first transistor; the second input terminal of the comparator is connected to a reference voltage, wherein preferably the second input terminal of the comparator is connected to the first terminal of the first transistor; the output terminal of the comparator is connected to an input terminal of the control unit.

[0014] The first terminal of the first transistor can be a source terminal, while the second terminal of the first transistor can be a drain terminal. Preferably, the control unit can be configured to switch to active mode if the voltage measured at the first transistor exceeds a predetermined threshold.

[0015] Preferably, the switching device may comprise a current blocking device designed to block any currents from the load terminal in the direction of the first transistor.

[0016] Preferably, the current blocking device can be designed as a diode arranged between the first terminal of the first transistor and the supply voltage terminal, the diode being connected on the anode side to the supply voltage terminal and on the cathode side to the first terminal of the first transistor; or arranged between the second terminal of the first transistor and the load terminal, the diode being connected on the anode side to the second terminal of the first transistor and on the cathode side to the load terminal.

[0017] Preferably, the switching device can comprise a third switching device which is designed as a third transistor and has a control terminal, a first terminal and a second terminal, wherein the first terminal is connected to the supply voltage terminal and the second terminal is connected to a second load terminal; wherein the third switching device is designed to provide a supply voltage to the second load terminal in a switched-on state, whereby a third current flows through a second load; the control unit is designed to transfer the third switching device into a switched-on state and a switched-off state by providing a third control signal to the control terminal of the third switching device;and the control unit is further configured to transfer the electronic switching device into a standby mode and into an active mode, wherein in standby mode the first switching device is switched on and the second switching device and the third switching device are switched off, and in active mode the first switching device, the second switching device and the third switching device are switched on.;

[0018] Preferably, the switching device may comprise a second current blocking device designed to block any currents from the second load terminal in the direction of the first transistor.

[0019] Preferably, the second current blocking device can be designed as a second diode which is arranged between the second terminal of the first transistor and the second load terminal, wherein the second diode is connected on the anode side to the second terminal of the first transistor and on the cathode side to the second load terminal.

[0020] Preferably, the switching device can comprise a fourth switching device which is designed as a fourth transistor and has a control terminal, a first terminal and a second terminal, wherein the first terminal is connected to the supply voltage terminal and the second terminal is connected to a third load terminal; wherein the fourth switching device is designed to provide a supply voltage to the third load terminal in a switched-on state, whereby a fourth current flows through a third load; the control unit is designed to transfer the fourth switching device into a switched-on state and a switched-off state by providing a fourth control signal to the control terminal of the fourth switching device;and the control unit is further configured to transfer the electronic switching device into a standby mode and into an active mode, wherein in standby mode the first switching device is switched on and the second switching device, the third switching device, and the fourth switching device are switched off, and in active mode the first switching device, the second switching device, the third switching device, and the fourth switching device are switched on.;

[0021] Preferably, the switching device may comprise a third current blocking device designed to block any currents from the third load terminal in the direction of the first transistor.

[0022] Preferably, the second current blocking device can be designed as a second diode which is arranged between the second terminal of the first transistor and the third load terminal, wherein the third diode is connected on the anode side to the second terminal of the first transistor and on the cathode side to the third load terminal.

[0023] Preferably, the first transistor may have an on-resistance Ds(on) that is greater than the on-resistance Ds(on) of the second transistor.

[0024] The invention is explained in more detail below with reference to the figures.

[0025] Fig. 1 shows a switching device according to the prior art,

[0026] Fig. 2 shows a first embodiment of the switching device according to the invention,

[0027] Fig. 3 shows a second embodiment of the switching device according to the invention,

[0028] Fig. 4 shows a third embodiment of the switching device according to the invention, and

[0029] Fig. 5 shows a fourth embodiment of the switching device according to the invention.

[0030] In Fig. 1, a switching device known from the prior art is shown

[0031] 10 for controlling loads in a motor vehicle is shown schematically. For simplicity, the loads are sketched in this figure as a (total) load 16. The switching device 10 has a control unit 14 designed to control a switching device 12. The switching device 12 is embodied as a MOSFET transistor and is connected between a supply terminal 26 and a load terminal 28. When the switching device 12 is switched on, the load 16 is supplied with the supply voltage Vss, so that a current flows through the load 16. Such a switching device can be used, for example, in electronic fuses, so that the switching device 12 is deactivated by the control unit 14 as soon as an excessive current through the load 16 is detected. However, such a switching device has the disadvantage that it can only switch between an switched on and an off state.The provision of a standby mode in which a reduced current is made available to the load 16 is not readily possible with the switching device 10 shown in Fig. 1.

[0032] Fig. 2 shows a first embodiment of the switching device 10 according to the invention. The switching device 10 has a control unit 14, a first switching device 12a and a second switching device 12b. The switching devices 12a and 12b are each embodied as transistors. In the embodiment shown, the switching devices 12a and 12b are designed as MOSFET transistors. The control unit 14 is configured to switch the first switching device 12a and the second switching device 12b on and off. In particular, it can be provided that a lower current can flow through the switching device 12a than through the second switching device 12b. This can be achieved by the first transistor having a larger on-resistance R.Ds(on) than the second transistor.This makes it possible to use the first transistor as a so-called "bypass" transistor, which provides a lower current than the second transistor. The bypass transistor can remain switched on in standby mode, while the second transistor is switched off in standby mode. This provides a relatively small current, which is used to operate those components in a vehicle that should remain permanently switched on. In contrast, in standby mode, the second transistor is switched off, thereby switching off those loads in the vehicle that have high consumption. The first switching device 12a, which is embodied as the first transistor, can preferably be equipped with a current-limiting circuit designed to limit the current flowing through the switching device 12a.

[0033] Fig. 3 schematically shows a second embodiment of the switching device 10 according to the invention. In this embodiment, in addition to the components shown in Fig. 2, a voltage evaluation unit 18 is provided which serves to evaluate a voltage at the first transistor. In the embodiment shown, the voltage evaluation unit 18 is designed as a comparator 20. The comparator is designed to evaluate the voltage between the second terminal (drain terminal) of the first transistor and a reference voltage. The voltage at the first terminal (source terminal) of the first transistor can serve as the reference voltage, for example. The comparator 20 is designed to deliver an output signal which signals to the control unit 14 that a predetermined threshold voltage at the first transistor has been exceeded.If the threshold voltage is exceeded, this can be interpreted as an indication that individual loads of the motor vehicle have been switched on, so that the control unit 14 can switch from the standby mode to the active mode.

[0034] Fig. 4 schematically shows a third embodiment of the switching device 10 according to the invention. In this embodiment, a current blocking device 22 is additionally provided, which is designed to block any currents from the load terminal 28 to the first transistor. In the embodiment shown in this figure, the current blocking device 22 is designed as a diode 24. The diode 24 is connected on the anode side to the second terminal (drain terminal) of the first transistor and on the cathode side to the load terminal 28. Alternatively, the diode 24 could also be arranged between the supply voltage terminal 26 and the first terminal (source terminal) of the first transistor, wherein the diode 24 in this case is connected on the anode side to the supply voltage terminal 26 and on the cathode side to the first terminal (source terminal) of the first transistor (not shown in Fig. 4).Furthermore, the current blocking device 22 can alternatively also be implemented by a switching device (in particular by a transistor) that prevents reverse currents from flowing into the first transistor. This protects the first transistor (not shown in Fig. 4).

[0035] Fig. 5 schematically shows a fourth embodiment of the switching device 10 according to the invention. In this embodiment, the first switching device 12a is connected to a plurality of switching devices 12b, 12c via a plurality of channels (two channels are shown in Fig. 5). In the embodiment shown, the connection is made via the second terminal of the first transistor (drain terminal), which is connected via a first diode 24a to the second terminal of the second transistor and via a second diode 24b to the second terminal of the third transistor. Different consumers in a motor vehicle can be supplied with energy via the individual channels. The first diode 24a and the second diode 24b ensure that the first transistor is protected from reverse currents (for example in the event of faults, such as a short circuit). In addition, the circuit shown in Fig.The embodiment shown in Fig. 5 has the advantage that only a single bypass transistor (first switching device 12a) is required if multiple channels are to be supplied. In addition, the embodiment shown in Fig. 5 is particularly advantageous if the switching device 10 has a voltage evaluation unit, in particular in the form of a comparator, which is designed to evaluate a voltage at the first transistor (as shown in Fig. 3). In this case, a single voltage evaluation unit, in particular in the form of a single comparator, can be used to generate a trigger signal (for example the output signal of the comparator) that causes the control unit 14 to switch from the standby mode to the active mode. A further advantage of the embodiment shown in Fig. 5 in combination with the aforementioned voltage evaluation unit can be seen in the fact that regardless of which of the channels the consumers orWhen loads in the motor vehicle are switched on, the voltage at the first transistor increases, and as a result, the device can be switched from standby mode to active mode. Although only two channels connected to the first transistor are provided in Fig. 5 for illustrative purposes, it is equally possible to provide three, four, or more than four channels, each connected to the first transistor via a diode.

[0036] LIST OF REFERENCE SYMBOLS Switching device Switching device a first switching device b second switching device c third switching device Control unit Load a first load b second load Voltage evaluation unit Comparator Current blocking device Diode a first diode b second diode Supply voltage connection Load connection a first load connection b second load connection

Claims

CLAIMS 1. An electronic switching device (10) for controlling loads in a motor vehicle, comprising a first switching device (12a) designed as a first transistor and having a control terminal, a first terminal, and a second terminal, the first terminal being connected to a supply voltage terminal (26) and the second terminal being connected to a load terminal (28); the first switching device (12a) being designed, in a switched-on state, to provide a supply voltage to the load terminal (28), whereby a first current flows through the first load; a second switching device (12b) designed as a second transistor and having a control terminal, a first terminal, and a second terminal, the first terminal being connected to the supply voltage terminal (26) and the second terminal being connected to a load terminal (28);wherein the second switching device is designed to provide the supply voltage at the load terminal (28) in a switched-on state, whereby a second current flows through the first load; wherein the first switching device (12a) and the second switching device (12b) are designed such that the second current is greater than the first current; and a control unit (14) which is designed to transfer the first switching device (12a) and the second switching device (12b) respectively into a switched-on state and a switched-off state by providing a first control signal at the control terminal of the first switching device (12a) and a second control signal at the control terminal of the second switching device (12b);wherein the control unit (14) is further designed to transfer the electronic switching device (10) into a standby mode and into an active mode, wherein in the standby mode the first switching device (12a) is switched on and the second; Switching device (12b) is switched off, and in active mode the first switching device (12a) is switched on and the second switching device (12b) is also switched on.

2. Switching device according to claim 1, characterized by a voltage evaluation unit (18) which is designed to detect a voltage at the first transistor and to generate an output signal as a function of the detected voltage, wherein the voltage evaluation unit (18) is designed to transmit the output signal to the control unit (14).

3. Switching device according to claim 2, characterized in that the voltage evaluation unit (18) is designed as a comparator (20) with two input terminals and one output terminal, wherein the first input terminal of the comparator (20) is connected to the second terminal of the first transistor; the second input terminal of the comparator (20) is connected to a reference voltage, wherein preferably the second input terminal of the comparator (20) is connected to the first terminal of the first transistor; the output terminal of the comparator (20) is connected to an input terminal of the control unit (14).

4. Switching device according to claim 2 or 3, characterized in that the control unit (14) is designed to switch to the active mode if the voltage measured at the first transistor exceeds a predetermined threshold value.

5. Switching device according to one of claims 1 to 4, characterized by a current blocking device (22) which is designed to block any currents from the load terminal (28) in the direction of the first transistor.

6. Switching device according to claim 5, characterized in that the current blocking device (22) is designed as a diode (24) which is arranged between the first terminal of the first transistor and the supply voltage terminal (26), the diode (24) being connected on the anode side to the supply voltage terminal (26) and on the cathode side to the first terminal of the first transistor; or is arranged between the second terminal of the first transistor and the load terminal (28), the diode (24) being connected on the anode side to the second terminal of the first transistor and on the cathode side to the load terminal (28).

7. Switching device according to one of claims 1 to 6, characterized in that the switching device has a third switching device (12c) which is designed as a third transistor and has a control terminal, a first terminal and a second terminal, wherein the first terminal is connected to the supply voltage terminal (26) and the second terminal is connected to a second load terminal (28b); wherein the third switching device (12c) is designed to provide a supply voltage to the second load terminal (28b) in a switched-on state, whereby a third current flows through a second load; the control unit (14) is designed to transfer the third switching device (12c) into a switched-on state and a switched-off state by providing a third control signal to the control terminal of the third switching device (12c).and the control unit (14) is further designed to transfer the electronic switching device (10) into a standby mode and into an active mode, wherein in the standby mode the first switching device (12a) is switched on and the second switching device (12b) and the third switching device (12c) are switched off, and in the active mode the first switching device (12a), the second; switching device (12b) and the third switching device (12c) are switched on.

8. Switching device according to claim 7, characterized by a second current blocking device which is designed to block any currents from the second load terminal (28b) in the direction of the first transistor and / or the first load terminal (28a).

9. Switching device according to claim 8, characterized in that the second current blocking device is designed as a second diode (24b) which is arranged between the second terminal of the first transistor and the second load terminal (28), the second diode (24) being connected on the anode side to the second terminal of the first transistor and on the cathode side to the second load terminal (28).

10. Switching device according to one of claims 1 to 9, characterized in that the first transistor has an on-resistance Ros(on) which is greater than the on-resistance Ros(on) of the second transistor.

11. Switching device according to one of claims 1 to 10, characterized in that the first switching device (12a) has a current limiting circuit.

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