Circuit arrangement, control device and vehicle

Abstract

The present invention relates to a circuit arrangement (1) with protection from electrostatic discharges, the arrangement comprising: at least one energy source; at least one element to be protected, in particular a semiconductor element; at least one connection point in order to supply a consumer connected thereto with energy, the circuit arrangement (1) being designed such that a corresponding supply voltage is applied to the connection point; and at least one ESD element (6), wherein the ESD element (6) has an operating voltage, is electrically connected to the energy source and the connection point at a first pole, is connected to earth at a second pole, and is suitable for discharging an electrostatic discharge between the connection point and the energy source, wherein a storage capacitor (8) is arranged between the second pole of the ESD element (6) and earth, and the operating voltage of the ESD element (6) is lower than the supply voltage which is applied to the connection point.

Description

[0001] 202501011

[0002] - 1 -

[0003] Circuit layout, control unit and vehicle

[0004] The present invention relates to a circuit arrangement and a control device that can access one or more sensors for environmental detection or environmental sensors (in particular radar sensor, lidar sensor, camera sensor or ultrasonic sensor), which has a circuit arrangement according to the invention, and to a vehicle which has a circuit arrangement and / or a control device according to the invention.

[0005] Technological background

[0006] Modern vehicles, such as cars and motorcycles, are increasingly equipped with driver assistance systems. These systems use sensors to perceive the surroundings, recognize traffic situations, and support the driver, for example, by applying the brakes or steering, or by issuing visual or audible warnings. Radar sensors, lidar sensors, cameras, ultrasonic sensors, and similar devices are commonly used for environmental perception. The sensor data collected by these devices allows for inferences to be drawn about the environment. Environmental perception using radar sensors is based on the emission of focused electromagnetic waves and their reflection, for example, by other road users, obstacles on the road, or roadside structures.

[0007] The (partially) automated control of the vehicle and its actuators (e.g., steering, engine, brakes, etc.) as well as sensor systems is increasingly handled by intelligent control units or control devices (e.g., ECU, Electronic Control Unit or ADCU, Assisted and Automated Driving Control Unit), which can access the actuators and sensors (e.g., for environmental perception). Electrostatic discharge (ESD) is of particular importance in modern control devices, as large potential differences can cause voltage breakdowns that can lead to short, high electrical currents (ESD pulses). This can damage ESD-sensitive components, which include almost all electrical, electronic, and optoelectronic components. In particular, ESD is one of the most frequent causes of failure in semiconductor-based integrated circuits.Circuits used in high-frequency technology, diode lasers, transistors (e.g., MOSFETs or IGBTs), and diodes are particularly sensitive, often only tolerating reverse voltages of 5–30 V without damage. 202501011.

[0008] -2 -

[0009] With increasing vehicle complexity and the move towards fully automated vehicles, the number of sensor systems, such as cameras and radar sensors, is growing, with Gigabit LVDS (Low Voltage Differential Signaling) or Ethernet connectivity. Modern integrated circuits (ICs) for such Gigabit LVDS or Ethernet connections are becoming increasingly sensitive to ESD because they are manufactured using smaller CMOS (Complementary Metal-Oxide-Semiconductor) structures, for example, with gate widths of 22 nm instead of the 65 nm used for conventional circuits. Many modern ICs therefore only have an ESD robustness of 2 kV, whereas older ICs with 65 nm CMOS typically exhibit an ESD robustness of 6 kV. Modern sensors also utilize the coaxial connector for power supply (Power over Coax or PoC). A key point here is that the HF (High Frequency or...The high-frequency signal is connected to the sensor, and the sensor is powered via a coaxial or shielded twisted-pair cable. This design makes the system simpler and more robust against EMC (electromagnetic compatibility) interference.

[0010] Fig. 1 shows a circuit arrangement 101 for ESD protection of Power-over-Coax (PoC) systems according to the prior art, comprising a high-speed IC 102 (e.g., a fine CMOS processor with low ESD resistance or ESD robustness of, for example, 2 kV HBM) with an I / O circuit 103 and internal ESD component 104, as well as a PoC filter 105. The output of the PoC filter 105 has a connection for an (external) load. In this example, the load is a sensor or environmental sensor (e.g., radar sensor or camera), which is connected to the connector via a coaxial connection. This connection serves both to supply power to the sensor and to transmit data, specifically the sensor signal, to the control unit.A typical sensor supply voltage (Vsensor) at the PoC output is, for example, 12 V, and a typical data rate is, for example, 4 Gbit / s. Therefore, newer systems with gate widths of 22 nm require ESD protection, e.g., in the form of an IC-external ESD component 106 (e.g., ESD circuit, ESD diode, ESD element, or the like), to improve robustness. The ESD component 106 must have a low capacitance to ensure good signal quality and a high breakdown voltage, typically much higher than the supply voltage applied to the environmental sensor via the coaxial cable.

[0011] In the described configuration, the electronic component should withstand ESD pulses with a rise time of 1 ns or less, in accordance with IEC 61000-4-2.

[0012] -3 -

[0013] exhibit and reach up to 6 kV or even 8 kV in the negative or positive direction (as exemplified in Fig. 2 using the prior art ESD pulse timing with two elements). One approach is to connect a bidirectional high-voltage ESD diode directly to the sensor's input terminal as the ESD component 106. For an environmental sensor (e.g., a camera or radar) with a sensor supply voltage of 12 V, the safe operating voltage of the ESD protection or ESD component 106 should therefore be 18 V. Additionally, a further external ESD component 108 (e.g., a bidirectional ESD diode or suppressor diode) with a lower voltage is required after the AC coupling capacitor 107, near the pin of the integrated circuit (IC 102) with a typical breakdown voltage of 5 V.The disadvantage is that with increasing ESD pulse voltage, the low-voltage ESD protection (via ESD component 108) triggers earlier than the high-voltage element (via ESD component 106), which directs current towards the sensitive IC 102 and can lead to damage, although the high-voltage ESD protection triggers somewhat later.

[0014] As soon as the ESD pulse reaches the protection circuit, it first triggers the low voltage and directs the current to the sensitive IC input, which is then exposed to the high voltage. Even if no external low-voltage ESD protection is present, the internal ESD protection via ESD component 104 of IC 102 could trigger first, pulling the pulse towards IC 102 and causing damage. Therefore, the problem with the circuit arrangement described above is that IC 102 can be damaged in the event of an ESD pulse.

[0015] Another disadvantage of the solution according to Fig. 1 is that the capacitance of two ESD diodes increases the interface impedance. This additional capacitance increases the return loss and creates an interface mismatch, which can lead to signal degradation due to reflected waves. Consequently, the operating frequency range of the circuit, as well as the data rate and the distance between the connections, are reduced. The effectiveness of the two ESD components 106 and 108 depends on the electrical length of the impedance trace between them. If there is a significant length in the circuit, the pulse reaches the ESD component 108 with a delay, which could cause the protection at component 106 to be triggered first, followed by that at component 108. This is particularly relevant for small sensors, especially sensors in vehicles for environmental sensing, such as...

[0016] Radar sensors, lidar sensors, camera sensors or ultrasonic sensors are often 202501011

[0017] - 4 -

[0018] However, only about 5 mm-10 mm of conductor track length is available, so the advantage of pulse delay cannot be used as an advantage for ESD protection.

[0019] Object of the present invention

[0020] Starting from the prior art, the object of the present invention is now to provide a circuit arrangement of the generic type in which ESD protection is improved in a simple and cost-effective manner and operational safety is increased.

[0021] Solution to the task

[0022] The aforementioned problem is solved by the entire teaching of claim 1 and the dependent claims. Advantageous embodiments of the invention are claimed in the dependent claims.

[0023] The circuit arrangement according to the invention, with protection against electrostatic discharge (ESD), comprises a power source, at least one element to be protected (in particular a semiconductor element), and at least one connection for supplying power to a connected load. Furthermore, the circuit arrangement is configured such that a supply voltage appropriate for the load is present at the connection. Additional components and assemblies may be provided for this purpose, such as a corresponding proof-of-concept (PoC) filter, converter, or the like. In addition, an ESD element or component is provided, wherein the ESD element has an operating voltage, is electrically connected to the power source and the connection at one pole, and is connected to ground at the other. The ESD element is suitable for dissipating an electrostatic discharge between the connection and the power source.A storage capacitor is arranged between the second pole of the ESD element and ground. This capacitor is dimensioned to withstand the ESD charge or ESD pulse, store it, and then discharge it (slowly and in a controlled manner) (e.g., via the ESD element, the component to be protected, an additional ESD component within the component to be protected, a PoC filter, a discharge resistor, or similar). The operating voltage of the ESD element is lower than the supply voltage applied to the connector. This ensures that the connector's ESD protection via the ESD component is not triggered earlier than the IC's internal ESD protection. This improves ESD protection and increases operational reliability. Furthermore, compared to the state of the art, the following is improved: 202501011.

[0024] -5 -

[0025] The consumer's supply voltage is effectively protected, and only one (external) ESD element is required, making the solution according to the invention simpler and more cost-effective to implement. The ESD element or component triggers for both negative and positive voltages.

[0026] According to an advantageous embodiment of the invention, the nominal voltage of the storage capacitor can scale with the ratio of ESD source capacitance to storage capacitance. The storage capacitor can be dimensioned accordingly.

[0027] Advantageously, the storage capacitor can have a nominal voltage of, for example, 50 V or 100 V, depending on the applied ESD voltage. The discharge of the storage capacitor to the IC then occurs either via internal IC protection or an ESD component contained within the IC, and / or via the ESD component, and / or via the PoC filter or PMIC (Power Management Integrated Circuit) ESD and discharge resistor.

[0028] Preferably, the element to be protected is an integrated circuit (IC) which is connected directly or via an AC capacitor to the power source and thus also to the first pole of the ESD element. However, other components, such as a transistor or a diode, could also be used as the component to be protected.

[0029] According to a preferred embodiment of the invention, the connection is a coaxial connection, so that the consumer is connected via a coaxial link which exhibits low electromagnetic interference and radiation as well as good electrical shielding. Furthermore, this allows for a so-called power-over-coax connection, whereby the consumer is supplied with power via the connection and data can be transmitted simultaneously.

[0030] Advantageously, a sensor, in particular a radar sensor, a camera, a lidar sensor, or an ultrasonic sensor, can be provided as the consumer, with the sensor signal also being transmitted via the connection (e.g., coaxial connection). An application to Power-over-Shielded Twisted Pair (power over shielded cable with twisted pairs) is also included according to an advantageous embodiment of the invention. For example, twisted pair cables with an aluminum foil as shielding, so-called F / UTP (Foiled Unshielded Twisted Pair), twisted pair cables with a copper braid as shielding, so-called S / UTP (Screened Twisted Pair), or cables with 202501011 can also be used.

[0031] -6 -

[0032] Additionally, shielded wire pairs, such as S / STP (Screened Shielded Twisted Pair) or S / FTP (Screened Foiled Twisted Pair), may be provided.

[0033] According to a particular embodiment of the invention, a further resistor or capacitor can be arranged in parallel with the storage capacitor. Preferably, the further capacitor has a lower electrical capacitance than the storage capacitor in order to achieve better response at high speeds. This parallel connection of a resistor or a capacitor ensures discharge, thereby further increasing operational reliability.

[0034] Furthermore, an additional resistive element, in particular a PTC protective resistor or PTC thermistor, can be provided between the ESD component (e.g., an ESD diode) and the storage capacitor. This is particularly advantageous in common-mode applications. To prevent damage to the components, a PTC fuse can be connected in series with the ESD component or ESD diode. This fuse, for example, becomes very high-resistance with increasing temperature at currents of approximately 50 mA and a resistance of 1 Ω. This further enhances operational reliability.

[0035] Furthermore, the present invention claims a control device comprising a circuit arrangement according to the invention.

[0036] Another aspect of the present invention relates to a vehicle comprising several actuators and at least one sensor, which includes a circuit arrangement and / or a control device according to the invention.

[0037] Description of the invention using an exemplary embodiment

[0038] In the circuit arrangement according to the invention, a low-voltage ESD element is used at the high-voltage connector, wherein a storage capacitor is arranged between the ESD element and ground, which is dimensioned such that it captures the charge of the ESD pulse (e.g. + / - 6000 V) and the voltage is significantly reduced, and which withstands the pulse voltage that occurs during the storage of the pulse.

[0039] -7 -

[0040] Fig. 3 shows a simplified representation of a circuit arrangement according to the invention for ESD protection in power-over-coaxial systems. The use of a low-voltage ESD protection device (with an operating voltage or breakdown voltage of, for example, 5 V) as the ESD component 6 makes it possible to trigger the protection path first at the output of the coaxial connector, since it has the lowest series impedance and trip voltage. The ESD charge is then stored in the storage capacitor 8 and increases the voltage to a comparable low voltage, which later triggers the internal ESD voltage of the high-speed IC 2 and via the DC path. The voltage of the storage capacitor 8 preferably scales with the ratio of ESD source capacitance (CESD) to storage capacitance (Cstorage).

[0041] For example, the source capacitance is 150 pF and the storage capacitance is 22 nF, resulting in a reduction factor of 146 on the voltage.

[0042] Fig. 4 shows a simplified representation of an embodiment of a circuit arrangement according to the invention for ESD protection of Power-over Shielded Twisted-Pair connections. Here, the circuit for the positive and negative supply voltages, which are present on the differential lines, is implemented twice. The shielding is connected to the ground of the control unit, and one differential line carries the positive voltage supply while another carries the negative voltage supply. For example, Power-over-Ethernet (PoE) uses this type of power supply in the range of 37 V to 57 V. Furthermore, the present invention can also be applied in the context of single-pair automotive Ethernet (SPE) when the power supply is to be provided via the cable.

[0043] To protect the ESD protection shown in Fig. 4 from common-mode currents, which can reach up to 250 mArms, a PTC protection resistor 9 is provided. The PTC protection resistor 9 heats up at a current of, for example, 50 mArms and reduces the current to such an extent that the ESD component, which is designed here as an ESD diode, is not thermally overloaded. During the circuit board design, care must be taken to ensure that the PTC and the ESD diode have good thermal contact so that the heating of the ESD diode also causes the PTC to quickly become highly resistive. This results in a significant current drop, and the ESD diodes are protected against overheating. Common-mode currents can be inductively coupled into the cable in the range of 100 kHz–400 MHz (bulk current injection, BCI). This is, for example, For example, in Automotive Ethernet, an EMC test is required for the conventional ESD circuitry of ESD components with a trigger voltage of more than 100 V.Therefore, these elements only offer limited protection to the circuits. In contrast, the 202501011...

[0044] - 8 -

[0045] The circuit described here better protects the integrated circuit (IC 2) and is robust against common-mode currents.

[0046] Figure 4 shows an example of the waveform of a significantly damped ESD pulse with a storage capacitor 8 according to the invention. Depending on the applied ESD voltage, a suitable capacitor with a nominal voltage of 50 V or 100 V could be used as the storage capacitor 8. The discharge of the storage capacitor 8 to the IC 2 then takes place either via the IC's internal ESD protection or ESD component 4, via the ESD component 6, and / or via the PoC filter 5 or PMIC (Power Management Integrated Circuit) ESD and discharge resistor.

[0047] Advantageously, another resistor could be arranged in parallel with the storage capacitor 8 (not shown in Fig. 3 / Fig. 4) to ensure discharge. The disadvantage here would be the leakage current, which should be avoided as it could impair the performance of the high-speed connection. For improved response at high speeds, a second (smaller) capacitor of 1 nF or less can be added (also not shown in Fig. 3 / Fig. 4).

[0048] Reference numeral 10 in Fig. 5 designates a vehicle which has a control unit 11 according to the invention (e.g., ECU, Electronic Control Unit or ADCU, Assisted and Automated Driving Control Unit), various actuators (steering 12, motor 13, brake 14), and sensors for environmental sensing or environmental sensors (radar sensor 15, camera 16, lidar sensor 17, and ultrasonic sensors 18a-18d). The vehicle 10 can be (partially) automated by the control unit 11 being able to access the actuators and the sensors or their sensor data. In the area of ​​assisted or (partially) automated driving, the sensor data can be used for environmental and object recognition, so that various assistants or assistance functions, such as…

[0049] Adaptive Cruise Control (ACC), Electronic Brake Assist (EBA), Lane Keep Assist (LKA), Park Assist, Traffic Jam Assist, or similar functions can be implemented via control unit 11 and the algorithm stored therein. 202501011

[0050] -9 -

[0051] REFERENCE MARK LIST

[0052] 1 Circuit arrangement

[0053] 2 (high-speed) ICs, 3 I / O circuits

[0054] 4 internal ESD component 5 PoC filter

[0055] 6 ESD component

[0056] 7 AC coupling capacitor 8 Storage capacitor

[0057] 9 PTC protective resistor 10 Vehicle

[0058] 11 Control unit

[0059] 12 Steering

[0060] 13 Engine

[0061] 14 Brake

[0062] 15 radar sensor

[0063] 16 cameras

[0064] 17 Lidar sensor

[0065] 18a Ultrasonic sensor

[0066] 18b Ultrasonic sensor

[0067] 18c ultrasonic sensor

[0068] 18d ultrasonic sensor

[0069] 101 Circuit layout 102 High-speed IC 103 I / O circuit

[0070] 104 (internal) ESD component 105 PoC filter

[0071] 106 ESD components

[0072] 107 AC coupling capacitor 108 ESD component

Claims

202501011 - 10 - PATENT CLAIMS 1. Circuit arrangement (1) with protection against electrostatic discharges, comprising at least one energy source, at least one element to be protected, in particular a semiconductor element, and at least one connection for supplying energy to a connected load, wherein the circuit arrangement (1) is configured such that a corresponding supply voltage is present at the connection, and at least one ESD element (6), wherein the ESD element (6) has an operating voltage, is electrically connected at a first pole to the energy source and the connection, is connected to ground at a second pole, and is suitable for dissipating an electrostatic discharge between the connection and the energy source, wherein a storage capacitor (8) is arranged between the second pole of the ESD element (6) and ground, and the operating voltage of the ESD element (6) is lower than the supply voltage applied to the terminal.

2. Circuit arrangement (1) according to claim 1, characterized in that the nominal voltage of the storage capacitor (8) scales with the ratio of ESD source capacitance (CESD) TO storage capacitance (Cstorage).

3. Circuit arrangement (1) according to claim 1 or 2, characterized in that the nominal voltage of the storage capacitor (8) is between 50 V and 100 V.

4. Circuit arrangement (1) according to one of the preceding claims, characterized in that the element to be protected is an IC (2) which is connected directly or via an AC capacitor (7) to the power source and thus also to the first pole of the ESD element (6).

5. Circuit arrangement (1) according to one of the preceding claims, characterized in that the connection is a coaxial connection. 202501011 - 11 - 6. Circuit arrangement (1) according to one of the preceding claims, characterized in that the connection is a shielded twisted pair connection.

7. Circuit arrangement (1) according to one of the preceding claims, characterized in that a sensor, in particular a radar sensor or a camera or a lidar sensor or an ultrasonic sensor, is provided as the consumer, and the sensor signal is also transmitted via the connection.

8. Circuit arrangement (1) according to one of the preceding claims, characterized in that a further resistive element or a further capacitor, preferably with a lower electrical capacitance than the storage capacitor (8), is connected in parallel to the storage capacitor (8).

9. Circuit arrangement (1) according to one of the preceding claims, characterized in that a further resistive element, in particular a PTC protective resistor (9), is provided between the ESD component (6) and the storage capacitor (8).

10. Control device (11) comprising a circuit arrangement (1) according to one of the preceding claims.

11. Vehicle (10) comprising several actuators and at least one sensor, and further comprising a circuit arrangement (1) and / or a control device (11) according to one of the preceding claims.

Images