Bottom protection for an electronic control unit

Abstract

At least one printed circuit board (6) of an electronic control unit (3), comprising a first connection (T1) for connecting the at least one printed circuit board (6) to a supply connection of a battery, a second connection (T2) for connecting a ground potential (G) of the at least one printed circuit board (6) to a ground connection of the battery, a third connection (T3) for connecting the at least one printed circuit board (6) to a supply connection (T5) of an external electronic device (4), a fourth connection (T4) for connecting the at least one printed circuit board (6) to a ground connection (T6) of the device (4), and a low-side protection unit (8) configured to disconnect the fourth connection (T4) from the ground potential (G) of the at least one printed circuit board (6) when a current flowing through the low-side protection unit (8) is greater than a predefined threshold current.

Description

[0001] The present invention relates to an electronic control unit (ECU) for a motor vehicle, comprising at least one printed circuit board, which includes circuits for controlling an external electronic device and / or for communicating with the external electronic device and / or for supplying the external electronic device with electrical power. The invention further relates to an electronic system comprising the ECU and the external electronic device, as well as to a method for operating the ECU.

[0002] In a motor vehicle, ECUs can control and / or communicate with one or more external electronic devices, such as sensors or actuators. In some cases, an ECU can also supply such an electronic device with electrical power. For this purpose, the ECU can be connected to the external electronic device by two conductors, for example, a cable, one of which connects the respective ground terminals.

[0003] A ground fault in the external electronic device or cable, such as a short circuit in the ground connection of the external electronic device or in the conductor connecting the ground connections to the vehicle body, can lead to damage to the ECU's circuit board, a conductor connecting the ECU to the external electronic device, and / or the cable due to overload. Instead of flowing through its dedicated high-current connector, the ECU ground current may flow, at least partially, through the external short circuit on the load side.

[0004] One objective of the present invention is to prevent the aforementioned damage due to such mass defects.

[0005] This objective is achieved through the respective subject matter of the independent claim. Further embodiments and preferred embodiments are the subject matter of the dependent claims.

[0006] The invention is based on the idea of ​​providing a low-side protection unit on the circuit board of the ECU, which isolates the ECU connection used to connect the ground connection of the external electronic device to the ECU from the ground potential of the ECU circuit board when a current flowing through the low-side protection unit is greater than a predefined threshold current.

[0007] According to one aspect of the invention, an electronic control unit (ECU) for a motor vehicle is provided. The ECU comprises at least one printed circuit board (PCB). The PCB has circuits for controlling an external electronic device of the motor vehicle and / or for communicating with the external electronic device and / or for supplying the external electronic device with electrical power. The PCB has a first terminal for connecting the PCB to a supply terminal of an external battery of the motor vehicle and a second terminal for connecting a ground potential of the PCB to a ground terminal of the external battery.The at least one printed circuit board (PCB) has a third terminal for connecting it to a power supply terminal of the external electronic device and a fourth terminal for connecting it to a ground terminal of the external electronic device. The PCB has a high-side switching unit configured to switchably connect the first terminal to the third terminal. The PCB has a low-side protection unit configured to switchably connect the fourth terminal to the ground potential of the PCB and to disconnect the fourth terminal from the ground potential of the PCB when a current flowing through the low-side protection unit, in particular an absolute value of the current flowing through the low-side protection unit, exceeds a predefined threshold current.

[0008] The ECU can be, for example, a domain control unit (DCU), a zonal control unit (ZCU), a body control unit (BCU), or another type of ECU, such as a car computer (CC).

[0009] The external electronic device and the external battery are referred to as external because they are not considered parts of the electronic control unit.

[0010] Typically, the external battery supply terminal is a positive voltage terminal. Consequently, the high-side protection unit is designated as such because it is located between the first and third terminals, and the low-side protection unit is designated as such because it is located between ground potential and the fourth terminal. The second terminal may also be connected to the ground potential of at least one circuit board.

[0011] The high-side switching unit comprises, in particular, one or more switches, which can be referred to as high-side switches, and a high-side driver configured to selectively open and close the high-side switches in order to establish a connection, in particular a communication connection, a control connection, and / or an electrical power supply connection, between the external electronic device and the respective circuits of the at least one printed circuit board, or between the external electronic device and the first terminal. The high-side switches can, for example, be configured as individual transistors, in particular field-effect transistors, such as MOSFETs.

[0012] The ground potential of at least one printed circuit board (PCB) can be determined by the electrical potential of a reference structure of the ECU, for example, a metallic housing part of the ECU. The PCB can have one or more ground connections, which are connected to each other and / or to the reference structure. If a component is connected to the ground potential of the PCB, this can be understood to mean that the respective component is connected to at least one of the ground connections.

[0013] The current flowing through the low-side protection unit can be measured, in particular by measuring a voltage drop across a shunt resistor or by directly measuring the current with a suitable sensor, such as a Hall sensor or a circuit with an integrated current sensor without a shunt.

[0014] It is noted that disconnecting the fourth terminal from the ground potential of at least one printed circuit board (PCB) can, but does not necessarily, involve galvanic isolation of the fourth terminal from the ground potential of the PCB. In particular, the isolation can also be achieved by sufficiently increasing the electrical resistance so that no significant current can flow between the fourth terminal and the ground potential of the PCB. The maximum current corresponding to the isolation can be predefined.

[0015] If the low-side protection unit determines that the current flowing through it exceeds the threshold current, this can be interpreted as the fourth terminal being short-circuited to another ground potential, such as the vehicle chassis. This can occur due to a short circuit in the conductor connecting the fourth terminal to the ground terminal of the electronic device, or a short circuit in the ground terminal of the electronic device itself. Since the low-side protection unit isolates the fourth terminal from the ground potential of at least one circuit board in this case, damage to the ECU, the external electronic device, and / or the respective connecting cable is prevented.

[0016] According to some embodiments, the low-side protection unit includes a shunt resistor connected to the fourth terminal to determine the current flowing through the low-side protection unit. The low-side protection unit includes a switch, also referred to as a low-side switch, located between the fourth terminal and the ground potential of the at least one printed circuit board (PCB), specifically between the shunt resistor and the ground potential of the PCB. The low-side protection unit includes a driver circuit configured to open the low-side switch when the current flowing through the shunt resistor exceeds the threshold current.

[0017] In other words, in this case, the current flowing through the shunt resistor corresponds to the current flowing through the low-side protection device. This current can be measured, in particular, by measuring the voltage drop across the shunt resistor or by directly measuring the current with a suitable sensor.

[0018] Consequently, it can be determined in a particularly simple way whether the condition for isolating the fourth terminal from the ground potential of at least one circuit board is met. On the other hand, such designs still allow for flexible adaptation of the low-side protection unit to different predefined threshold currents according to the specific application.

[0019] The shunt resistor is arranged, in particular, between the fourth terminal and the ground potential of the at least one printed circuit board. Specifically, the shunt resistor and the low-side switch are connected in series between the fourth terminal and the ground potential of the at least one printed circuit board.

[0020] The low-side switch can, for example, be implemented as a transistor, in particular a field-effect transistor, such as a MOSFET. In this case, opening the low-side switch can be understood as controlling the transistor, especially by the driver circuit, to assume an open state, also referred to as an off state, although galvanic isolation is not necessarily achieved.

[0021] In some versions, the low-side protection unit may also have one or more additional low-side switches, which are opened, for example, by the driver circuit when the current flowing through the shunt resistor is greater than the threshold current to disconnect the fourth terminal from the ground potential of at least one circuit board.

[0022] According to some versions, the low-side protection unit includes a current sensor, with the shunt resistor terminals connected to the current sensor's input terminals. The driver circuit is connected to an output terminal of the current sensor.

[0023] In particular, the shunt resistor has two terminals, one of which is connected to the fourth terminal and the other to the ground potential of at least one circuit board. The current sensor has two input terminals, each of which is connected to one of the terminals of the shunt resistor.

[0024] Consequently, the voltage drop across the shunt resistor can be measured by the current sensor. The output signal of the current sensor thus indicates the current; for example, it is directly proportional to the current flowing through the shunt resistor.

[0025] The current sensor can, for example, include or consist of a current sensing amplifier.

[0026] Consequently, it can be determined in a particularly simple way whether the condition for disconnecting the fourth terminal from the ground potential of at least one circuit board is met.

[0027] According to some descriptions, the current sensor is configured to generate an output signal at its output terminal, indicating the current flowing through the shunt resistor. The driver circuit is then configured to compare this output signal, either directly or indirectly, to the threshold current.

[0028] In particular, the current sensor is designed to generate the output signal depending on the voltages present at its input terminals.

[0029] In particular, the driver circuit is configured to open the low-side switch depending on the result of the comparison, especially if the current flowing through the shunt resistor is greater than the threshold current.

[0030] According to some embodiments, the low-side protection unit includes an additional switch, also referred to as a secondary low-side switch, wherein the low-side switch and the secondary low-side switch are connected in series between the shunt resistor and the fourth terminal, or between the shunt resistor and the ground potential of at least one printed circuit board. The driver circuit is configured to open the low-side switch and the secondary low-side switch when the current flowing through the shunt resistor exceeds the threshold current.

[0031] In particular, the low-side switch and the additional low-side switch can function as a bidirectional switch. Consequently, the fourth terminal can be disconnected from the ground potential of at least one circuit board if the absolute value of the current flowing through the low-side protection unit exceeds the threshold current, regardless of the current direction. This further increases the reliability in preventing damage.

[0032] According to some explanations, the low-side switch and the other low-side switch are MOSFETs whose drain terminals are connected together.

[0033] In particular, the MOSFETs can each be operated in enhancement mode. For example, two n-channel MOSFETs can be used.

[0034] In this way, a bidirectional switch can be implemented in a simple manner.

[0035] According to some embodiments, the low-side protection unit includes a fuse arranged between the fourth terminal and the ground potential of at least one circuit board. The fuse is designed and arranged to disconnect the fourth terminal from the ground potential of the at least one circuit board when the current flowing through the fuse exceeds the threshold switch.

[0036] The fuse rating can be adapted to the threshold current. Consequently, it can be determined in a particularly simple way whether the condition for disconnecting the fourth terminal from the ground potential of at least one circuit board is met and no further electronic circuit is required to initiate the disconnection.

[0037] According to some descriptions, the low-side protection unit has a PTC thermistor that is located between the fourth terminal and the ground potential of at least one circuit board, and whose critical temperature is adapted to the threshold current.

[0038] At temperatures exceeding the critical temperature, the resistance of the PTC thermistor increases significantly. By applying Joule's law and considering the expected ambient temperature range, the PTC thermistor can be selected such that its critical temperature is reached when the current through the low-side protection device, specifically the PTC thermistor, matches the threshold current for predefined reference conditions, including, for example, a reference ambient temperature. Consequently, it can be determined in a particularly simple manner whether the condition for disconnecting the fourth terminal from the ground potential of at least one printed circuit board is met, and no additional electronic circuitry is required to initiate the disconnection.

[0039] According to some embodiments, the low-side protection unit includes a switch, also referred to as a low-side switch, located between the fourth terminal and the ground potential of at least one printed circuit board. The low-side protection unit includes a driver circuit configured to open the low-side switch when the current flowing through the low-side protection unit exceeds the threshold current.

[0040] The switch could, for example, be a MOSFET, which can be operated in depletion mode, and / or it could be an n-channel MOSFET. For example, one drain terminal of the MOSFET could be connected to the fourth terminal.

[0041] The low-side protection unit can, for example, include a diode connected in parallel to the switch, the cathode of which is connected in particular to the fourth terminal.

[0042] In several embodiments, the driver circuit is an integrated circuit configured to monitor the current flowing through the low-side protection unit, in particular through the switch, and to open the switch when the monitored current is greater than the threshold current.

[0043] According to some descriptions, the ECU has a housing, with at least one circuit board located inside the housing and the second connection being connected to the housing.

[0044] In particular, the housing is a metal housing or the housing has a metallic housing part to which the second terminal is connected. In other words, the ground potential of at least one switch plate corresponds to a reference potential of the metal housing or metallic housing part.

[0045] According to a further aspect of the invention, an electronic system is provided. The electronic system comprises an electronic control unit according to the invention and the external electronic device, wherein the power supply terminal of the external electronic device is connected to the third terminal and the ground terminal of the external electronic device is connected to the fourth terminal.

[0046] According to some versions of the electronic system, the ECU is configured to transmit a control signal for controlling the external electronic device via the third connection to the power supply connection of the external electronic device.

[0047] According to some versions of the electronic system, the ECU is designed to supply electrical power to the external electronic device via the third port and the power supply port of the external electronic device.

[0048] According to some versions of the electronic system, the system includes a coaxial cable. The power supply connection of the external electronic device is connected to the third terminal via a core conductor of the coaxial cable. The ground connection of the external electronic device is connected to the fourth terminal via a shield conductor of the coaxial cable.

[0049] Consequently, the ECU can transmit control signals to the external electronic device via the core conductor and / or transmit communication signals to or from the external electronic device via the core conductor and / or supply the external electronic device with electrical power via the core conductor.

[0050] This can be particularly advantageous if the external electronic device is a sensor device, such as a camera or other environmental sensor system of the vehicle.

[0051] According to some versions of the electronic system, the system has a first conductor and a second conductor, specifically a cable with the first and second conductors. The power supply terminal of the external electronic device is connected to the third terminal via the first conductor. The ground terminal of the external electronic device is connected to the fourth terminal via the second conductor.

[0052] Consequently, the ECU can transmit control signals to the external electronic device via the first conductor and / or transmit communication signals to or from the external electronic device via the first conductor and / or supply the external electronic device with electrical power via the first conductor.

[0053] According to some descriptions, the external electronic device has an additional circuit board. The power supply connection of the external electronic device is connected to this additional circuit board, and the ground connection of the external electronic device is connected to a ground potential of the external electronic device.

[0054] For example, the ground potential of the external electronic device is determined by the ground potential of the other circuit board, which may correspond to the potential of a device housing. The above explanations regarding the at least one circuit board, the ground potential of the at least one circuit board, and the ECU housing can be applied analogously.

[0055] According to some descriptions, the external electronic device has a device housing, the further circuit board is arranged inside the device housing, and the ground connection of the external electronic device is connected to the device housing.

[0056] Specifically, the device housing is a metallic housing or includes a metallic housing component to which the ground connection of the external electronic device is connected. In other words, the ground potential of the external electronic device corresponds to a reference potential of the metallic housing or metallic housing component.

[0057] According to some accounts, the external electronic device has a sensor system or an actuator system for the motor vehicle or vehicle.

[0058] The sensor system can be, for example, an environmental sensor system, such as a camera, lidar system, radar system, ultrasonic sensor system, light sensor, and so on. The sensor system can also be a microphone, an inertial measurement unit (IMU), a wheel speed sensor, a steering angle sensor, and so on.

[0059] The actuator system can include, for example, a brake actuator, a steering actuator, an electric motor, and so on.

[0060] Further embodiments of the electronic system according to the invention arise directly from the various embodiments of the ECU according to the invention, and vice versa. In particular, individual features and corresponding explanations as well as advantages relating to the various embodiments of the ECU according to the invention can be transferred analogously to corresponding embodiments of the electronic system according to the invention.

[0061] According to a further aspect of the invention, an electronic vehicle guidance system is provided for the motor vehicle. The electronic vehicle guidance system comprises an ECU or an electronic system according to the invention.

[0062] An electronic vehicle control system can be understood as an electronic system designed to control a vehicle fully automatically or autonomously, and in particular, without the need for manual intervention or control by a driver or user of the vehicle. The vehicle automatically performs all necessary functions, such as steering, braking, and / or acceleration maneuvers, as well as monitoring and recording road traffic and reacting accordingly. Specifically, the electronic vehicle control system can implement a fully automatic or fully autonomous driving mode according to Level 5 of the SAE J3016 classification. An electronic vehicle control system can also be implemented as an Advanced Driver Assistance System (ADAS), which assists a driver in semi-automated or semi-autonomous driving.In particular, the electronic vehicle guidance system can implement a semi-automatic or semi-autonomous driving mode according to levels 1 to 4 of the SAE J3016 classification. Here and in the following, SAE J3016 refers to the corresponding standard dated April 2021.

[0063] At least partially automated driving of the vehicle can therefore include driving the vehicle in a fully automated or fully autonomous driving mode according to level 5 of the SAE J3016 classification. At least partially automated driving of the vehicle can also include driving the vehicle in a semi-automated or semi-autonomous driving mode according to levels 1 to 4 of the SAE J3016 classification.

[0064] According to a further aspect of the invention, a method according to the invention for operating an ECU is provided. In this method, the fourth terminal is disconnected from the ground potential of the at least one circuit board by the low-side protection unit when the current flowing through the low-side protection unit is greater than the predefined threshold current.

[0065] Further embodiments of the method according to the invention arise directly from the various embodiments of the ECU and the electronic system according to the invention, and vice versa. In particular, individual features and corresponding explanations as well as advantages relating to the various embodiments of the ECU or the electronic system according to the invention can be transferred analogously to corresponding embodiments of the method according to the invention. In particular, the ECU or the electronic system according to the invention is designed or programmed to carry out the method according to the invention. In particular, the ECU or the electronic system according to the invention carries out the method according to the invention.

[0066] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figures, may be encompassed by the invention not only in the combinations specified, but also in other combinations. In particular, the invention may also encompass embodiments and combinations of features that do not have all the features of an originally formulated claim. Furthermore, the invention may encompass embodiments and combinations of features that go beyond or deviate from the combinations of features set out in the references to the claims.

[0067] The invention is explained in detail below with reference to specific exemplary embodiments and corresponding schematic drawings. Identical or functionally equivalent elements may be designated with the same reference numerals in the drawings. The description of identical or functionally equivalent elements is not necessarily repeated with respect to different figures.

[0068] The figures show: Fig. 1 schematically a motor vehicle with an exemplary embodiment of an electronic system according to the invention; Fig. 2 a schematic block diagram of an exemplary embodiment of an ECU according to the invention; Fig. 3 a schematic block diagram of a further exemplary embodiment of an ECU according to the invention; Fig. 4 a schematic block diagram of a low-side protection unit of a further exemplary embodiment of an ECU according to the invention; Fig. 4 a schematic block diagram of a low-side protection unit of a further exemplary embodiment of an ECU according to the invention; Fig. 5 a schematic block diagram of a low-side protection unit of a further exemplary embodiment of an ECU according to the invention; Fig. 6 a schematic block diagram of a low-side protection unit of a further exemplary embodiment of an ECU according to the invention; Fig. 7 a schematic block diagram of a further exemplary embodiment of an electronic system according to the invention; and Fig. 8 a schematic block diagram of a further exemplary embodiment of an electronic system according to the invention.

[0069] Fig. Figure 1 schematically shows a motor vehicle 1 with an exemplary embodiment of an electronic system 2 according to the invention. The electronic system 2 comprises an ECU 3 according to the invention and an external electronic device 4 of the motor vehicle 1, for example a sensor system, an actuator system or another electrical load of the motor vehicle 1. The electronic system 2 or the ECU 3 can, for example, be part of an electronic vehicle guidance system of the motor vehicle 1.

[0070] Fig. Figure 2 shows a schematic block diagram of an exemplary embodiment of an ECU 3 according to the invention. The ECU 3 includes a printed circuit board 6 with circuits (not shown) for controlling the external electrical device 4 and / or for communicating with the external electronic device 4 and / or for supplying the external electronic device 4 with electrical power, in particular via a cable 5 which connects the external electronic device 4 to the ECU 3.

[0071] The circuit board 6 has a first terminal T1 for connecting the circuit board 6 to a supply terminal of an external battery (not shown) of the motor vehicle 1 and a second terminal T2 for connecting a ground potential G of the at least one circuit board 6 to a ground terminal or external battery. The circuit board 6 has a third terminal T3 for connecting the circuit board 6 to a supply terminal T5 of the external electronic device 4 and a fourth terminal T4 for connecting the circuit board 6 to a ground terminal T6 of the external electronic device 4.The circuit board 6 has a high-side switching unit 7, which is configured to connect the first terminal T1 to the third terminal T3, and a low-side protection unit 8, which is configured to switchably connect the fourth terminal T4 to the ground potential G of the at least one circuit board 6 and to disconnect the fourth terminal T4 from the ground potential G of the at least one circuit board 6 when a current flowing through the low-side protection unit 8 is greater than a predefined threshold current.

[0072] For example, the ground potential terminals G can be DC-coupled to a metallic housing 9 of the ECU 3 via respective connections 10. For example, the first terminal T1 can be connected to the circuits of the circuit board 6 via a shunt resistor 11, and the second terminal T2 can be connected to ground potential G via a shunt resistor 12.

[0073] Fig. Figure 3 shows a schematic block diagram of a further advantageous embodiment of an ECU 3 according to the invention, which is based on the embodiment of Fig. 2 is based. Here, the ground potential connections G are coupled to the metallic housing 9 of the ECU 3 via respective capacitive couplings 13, in particular DC-decoupled and AC-coupled.

[0074] Fig. Figure 4 shows a schematic block diagram of the low-side protection unit 7 of an ECU 3 according to the invention, for example an ECU 3 as described in relation to Fig. 2 or Fig. 3 described.

[0075] The low-side protection unit 7 comprises a switch 22, which is arranged between the fourth terminal T4 and the ground potential G of the at least one circuit board 6. The low-side protection unit 7 further comprises a driver circuit 23, which is configured to open the switch 22 when the current flowing through the low-side protection unit 7 is greater than the threshold current.

[0076] The switch 22 is, for example, a MOSFET, in particular an n-channel MOSFET, operated in depletion mode, with its drain terminal connected to the fourth terminal T4 and its source terminal to ground potential G. The low-side protection unit 7 may also include a diode 23 connected in parallel to the switch 22, the cathode of which is connected to the fourth terminal T4.

[0077] The driver circuit 16, for example, is an integrated circuit configured to monitor the current flowing through the switch 22 and to open the switch 22 when the monitored current exceeds the threshold current. Depending on the complexity of the actual implementation, the integrated circuit can provide various functions for protecting the MOSFET and / or the external electronic device 4, such as current level measurement, overcurrent protection, and / or temperature detection.

[0078] Fig. Figure 5 shows a schematic block diagram of the lower side protection unit 7 of an ECU 3 according to the invention, for example an ECU 3 as described in relation to Fig. 2 or Fig. 3 described.

[0079] The low-side protection unit 7 of the Fig. 5 has a shunt resistor 14 and at least one low-side switch 17, 18. The shunt resistor 14 and the at least one low-side switch 17, 18 are connected in series between the fourth terminal T4 and the ground potential G of the circuit board 6.

[0080] The low-side protection unit 7 includes a current-sensing amplifier 15, the input terminals of which are connected to the two terminals of the shunt resistor 14. The low-side protection unit 7 includes a driver circuit 16, which is connected to an output terminal of the current-sensing amplifier 15. The current-sensing amplifier 15 generates an output signal at its output terminal, indicating the current flowing through the shunt resistor 14. The driver circuit 16 receives the output signal from the output terminal of the current-sensing amplifier 15 and, based on the output signal, compares the current flowing through the shunt resistor 14 with the threshold current. If the current flowing through the shunt resistor 14 is greater than the threshold current, the driver circuit 16 opens at least one low-side switch 17, 18.

[0081] The at least one low-side switch 17, 18 can, for example, have two MOSFETs connected in series, which are connected to each other at their drain terminals. This enables the low-side protection unit 7 to interrupt currents in both directions. In the example of Fig. In section 5, the MOSFETs are implemented as n-channel MOSFETs operated in enhancement mode. Specifically, the MOSFETs of switches 17 and 18 each incorporate intrinsic body diodes.

[0082] Fig. Figure 6 shows a schematic block diagram of the lower side protection unit 7 of an ECU 3 according to the invention, for example an ECU 3 as described above. Fig. 2 or Fig. 3 described. The low-side protection unit 7 in Fig. 6 resembles the low-side protection unit 7 in Fig. 5, but the MOSFETs are implemented as n-channel MOSFETs operating in depletion mode. The driver circuit 16 can, for example, be implemented as a bidirectional current-sensing amplifier.

[0083] Fig. Figure 7 shows a schematic block diagram of the lower side protection unit 7 of an ECU 3 according to the invention, for example an ECU 3 as described above. Fig. 2 or Fig. 3 described. The low-side protection unit 7 in Fig. 7 is similar to the low-side protection unit in Fig. 6. In the embodiment of Fig. However, the driver circuit 16 comprises a comparator 27, whose input terminals are connected to the respective sides of the shunt resistor 14, and another comparator 28, whose input terminals are also connected to the respective sides of the shunt resistor 14. The output terminal of comparator 27 is connected to the gate terminal of the MOSFET of switch 17, and the output terminal of the other comparator 28 is connected to the gate terminal of the MOSFET of switch 18.

[0084] Fig. Figure 8 shows a schematic block diagram of a further exemplary embodiment of an electronic system 2 according to the invention. The ECU 3 of the electronic system 2 can be an ECU 3, as described in relation to Fig. 2 to Fig. As described in section 7, cable 5 is a coaxial cable whose core conductor connects the power supply terminal T5 of the external electronic device 4 to the third terminal T3. A shield conductor of the coaxial cable connects the ground terminal T6 of the external electronic device 4 to the fourth terminal T4. The external electronic device 4 could, for example, be an environmental sensor system, such as a camera.

[0085] Fig. Figure 9 shows a schematic block diagram of a further exemplary embodiment of an electronic system 2 according to the invention. The ECU 3 of the electronic system 2 can be an ECU 3, as described in relation to Fig. 2 to Fig. As described in section 7, cable 5 has a first conductor that connects the power supply terminal T5 of the external electronic device 4 to the third terminal T3. A second conductor of cable 5 connects the ground terminal T6 of the external electronic device 4 to the fourth terminal T4. The external electronic device 4 could be, for example, a USB load, an ultrasonic sensor, a microphone, etc.

[0086] ECUs 3, in particular high-performance ECUs for driver assistance systems, ADAS, or other electronic vehicle systems, for example for autonomous or semi-autonomous driving, can draw high power from the vehicle's battery 1 via the second terminal T2, and the current is returned to the battery via a second terminal T2. External electronic devices 4, including but not limited to cameras, phantom-powered microphones, ultrasonic sensors, and so on, can be powered by the ECU via two electrical connections, namely the power connection and the ground connection, via the third and fourth terminals T3 and T4, respectively.

[0087] The high-side switching unit 7 can be used to supply electrical power to an external electrical device 4. The high-side switching unit 7 can also provide diagnostic and detection functions for the external electronic device, including, for example, current level measurement, open-circuit detection on the load side, overcurrent protection, battery short-circuit detection, and so on.

[0088] If the load-mass connection is damaged and accidentally comes into contact with other masses in the motor vehicle, including the chassis 19 of the motor vehicle 1 (see Fig. 5 and Fig. 6), if the circuit is short-circuited, there is a risk that the entire high ground current of the ECU will flow through the unprotected ground connection of the external electronic device 4. This can lead to damage to the electrical connection, namely the cable 5 itself, damage to the respective connectors, or damage to the circuit board 6.

[0089] The low-side protection unit 7 protects against all these risks and can also provide a diagnostic function in some versions.

[0090] The in the Fig. 5 to Fig.The implementations of the low-side protection unit 7 shown in Figure 7 are particularly advantageous for several reasons. For example, the current through the low-side protection unit 7 can be continuously monitored by monitoring the voltage drop across the shunt resistor 14. If a negative current, or reverse current, through the shunt resistor 24 is detected and the current exceeds a certain threshold, the driver circuit 16 can open both switches 17 and 18, in particular, turn off both MOSFETs. Since these MOSFETs are connected back-to-back, no current flows through them when their channels are off.

[0091] In some implementations, the driver circuit 16 can also implement positive current monitoring and / or positive overcurrent protection.

[0092] Possible implementations of the low-side protection unit 7 include active current limiters, such as a discrete version with active elements, and active low-side switches, for example, implemented as integrated circuits. The latter can be particularly suitable for protection against unlimited short-circuit events and can provide very fast detection and response. Monitoring functions, such as monitoring the current level, can also be provided. Furthermore, active current level control can be implemented.

Claims

[1] Electronic control unit (3) for a motor vehicle (1) comprising at least one printed circuit board (6), comprising - Circuits for controlling an external electronic device (4) and / or for communicating with the external electronic device (4) and / or for supplying the external electronic device (4) with electrical power; - a first connection (T1) for connecting the at least one circuit board (6) to a supply connection of an external battery of the motor vehicle (1); - a second connection (T2) for connecting a ground potential (G) of at least one circuit board (6) to a ground connection of the external battery; - a third connection (T3) for connecting the at least one circuit board (6) to a power supply connection (T5) of the external electronic device (4); - a fourth connection (T4) for connecting the at least one circuit board (6) to a ground connection (T6) of the external electronic device (4); - a high-side switching unit (7) which is configured to connect the first terminal (T1) to the third terminal (T3) in a switchable manner; and - a low-side protection unit (8) which is configured to connect the fourth terminal (T4) to the ground potential (G) of the at least one printed circuit board (6) and to disconnect the fourth terminal (T4) from the ground potential (G) of the at least one printed circuit board (6) when a current flowing through the low-side protection unit (8) is greater than a predefined threshold current. [2] Electronic control unit (3) according to claim 1, wherein the lower side protection unit (8) - has a shunt resistor (14) which is connected to the fourth terminal (T4) to determine the current flowing through the low-side protection unit (8); - has a switch (17) which is arranged between the fourth terminal (T4) and the ground potential (G) of the at least one circuit board (6); and - has a driver circuit (16) which is configured to open the switch (17) when a current flowing through the shunt resistor (14) is greater than the threshold current. [3] Electronic control unit (3) according to claim 2, wherein - the low-side protection unit (8) has a current sensor (15), wherein terminals of the shunt resistor (14) are connected to input terminals of the current sensor (15); and - the driver circuit (16) is connected to an output terminal of the current sensor (15). [4] Electronic control unit (3) according to claim 3, wherein - the current sensor (15) is configured to generate an output signal indicating the current flowing through the shunt resistor (14) at the output terminal of the current sensor (15); - the drive circuit (16) is set up to compare the current flowing through the shunt resistor (14) with the threshold current based on the output signal. [5] Electronic control signal (3) according to one of claims 2 to 4, wherein - the low-side protection unit (8) has a further switch (18), wherein the switch (17) and the further switch (18) are connected in series between the shunt resistor (14) and the fourth terminal (T4) or between the shunt resistor (14) and the ground potential (G) of the at least one circuit board (6); and - the driver circuit (16) is configured to open the switch (17) and the further switch (18) when the current flowing through the shunt resistor (14) is greater than the threshold current. [6] Electronic control unit (3) according to claim 5, wherein the switch (17) and the further switch (18) are MOSFETs whose drain terminals are connected to each other. [7] Electronic control unit (3) according to claim 1, wherein the lower side protection unit (8) - has a fuse arranged between the fourth terminal (T4) and the ground potential (G) of the at least one circuit board (6), and is configured to disconnect the fourth terminal (T4) from the ground potential (G) of the at least one circuit board (6) when a current flowing through the fuse is greater than the threshold current; or - has a PTC thermistor which is arranged between the fourth terminal (T4) and the ground potential (G) of the at least one circuit board (6) and whose critical temperature is adapted to the threshold current. [8] Electronic control unit (3) according to claim 1, wherein the lower side protection unit (8) - has a switch (22) which is arranged between the fourth terminal (T4) and the ground potential (G) of the at least one circuit board (6); and - has a driver circuit (23) which is configured to open the switch (22) when the current flowing through the low-side protection unit (8) is greater than the threshold current. [9] Electronic control unit (3) according to claim 8, wherein - the switch (22) is a MOSFET; and / or - the lower side protection unit (8) includes a diode (23) which is connected in parallel to the switch (22). [10] Electronic control unit (3) according to one of claims 8 or 9, wherein the driver circuit (16) is an integrated circuit configured to monitor the current flowing through the low-side protection unit (8) and to open the switch (22) when the monitored current is greater than the threshold current. [11] Electronic control unit (3) according to one of the preceding claims, which has a housing (9), wherein the at least one circuit board (6) is arranged inside the housing (9) and the second connection (T2) is electrically connected to the housing (9). [12] Electronic control unit (3) according to claim 1, which is configured as a domain control unit or a zone control unit or a body control unit. [13] Electronic system (2) comprising an electronic control unit (3) according to one of the preceding claims and the external electronic device (4), wherein the power supply terminal (T5) of the external electronic device (4) is connected to the third terminal (T3) and the ground terminal (T6) of the external electronic device (4) is connected to the fourth terminal (T4). [14] Electronic system (2) according to claim 13, comprising a coaxial cable, wherein - the power supply connection (T5) of the external electronic device (4) is connected to the third connection (T3) by a core conductor of the coaxial cable; and - the ground terminal (T6) of the external electronic device (4) is connected to the fourth terminal (T4) via a shield conductor of the coaxial cable. [15] Electronic system (2) according to one of claims 13 or 14, wherein the electronic control unit (3) is configured to transmit a control signal for controlling the external electronic device (4) via the third connection (T3) to the supply connection (T5) of the external electronic device (4). [16] Electronic system (2) according to any one of claims 13 to 15, wherein the electronic control unit (3) is configured to supply the external electronic device (4) with electrical power via the third connection (T3) and the power supply connection (T5) of the external electronic device (4). [17] Electronic system (2) according to any one of claims 13 to 16, wherein the external electronic device (4) comprises a further printed circuit board (20), wherein - the power supply connection (T5) of the external electronic device (4) is connected to the other circuit board (20); and - the ground terminal (T6) of the external electronic device (4) is connected to a ground potential of the external electronic device (4). [18] Electronic system (2) according to any one of claims 13 to 17, wherein the external electronic device (4) has a device housing (21), the further circuit board (20) is arranged inside the device housing (21) and the ground connection (T6) of the external electronic device (4) is connected to the device housing (21). [19] Electronic system (2) according to any one of claims 13 to 18, wherein the external electronic device (4) comprises a sensor system or an actuator system for the motor vehicle (1). [20] Method for operating an electronic control unit (3) according to any one of claims 1 to 12, wherein the fourth terminal (T4) is disconnected from the earth potential (G) of the at least one circuit board (6) by the low-side protection unit (8) when the current flowing through the low-side protection unit (8) is greater than the predefined threshold current.

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