Protection circuit, electronic control unit and vehicle

Abstract

Provided in the embodiments of the present disclosure are a protection circuit, an electronic control unit and a vehicle. Provided is a protection circuit. The protection circuit comprises: a voltage stabilizing unit, which comprises a first end that is adapted to be connected to an output end of a controller; a filter unit, which is configured to filter a signal, and comprises a first end connected to a second end of the voltage stabilizing unit and a second end that is adapted to be connected to a first end of a sensor; and a cut-off unit, which comprises a first end connected to the second end of the filter unit, a second end that is adapted to be connected to a second end of the sensor, and a third end connected to the ground, wherein the voltage stabilizing unit is configured to stabilize a voltage at the output end of the controller at a predetermined voltage when a first voltage at the filter unit exceeds a predetermined threshold value, and the cut-off unit is configured to be open when the first voltage is higher than the predetermined threshold value. In this way, by means of providing in the protection circuit a ground cut-off unit for the sensor, the controller and the sensor are protected from being damaged in the event of a high-voltage short circuit.

Description

Protection circuit, electronic control unit and vehicle TECHNICAL FIELD

[0001] The present disclosure relates to the electrical field, and more specifically, to a protection circuit, an electronic control unit and a vehicle. BACKGROUND

[0002] Under the background of the global automobile industry accelerating the transformation to low carbonization and electrification, increasing the voltage of the power system has become one of the key paths to optimize energy consumption and reduce carbon emissions. The electronic control unit (ECU) used in traditional fuel vehicles and early new energy vehicles is mostly based on mature 12-volt power supply architecture design, and the power input and the voltage resistance specification of electronic components are strictly matched with the 12-volt working environment, which has obvious advantages in cost control and technology maturity, and has effectively ensured the stable operation of the automobile electronic system for a long time.

[0003] To comply with increasingly stringent carbon emission requirements, the automobile industry is actively promoting 48-volt mild hybrid power systems and gradually introducing higher voltage platforms. The 48-volt system can effectively improve the operating efficiency of electric accessories such as electronic turbochargers and active suspensions, reducing engine load, thereby directly helping to reduce carbon emissions. SUMMARY

[0004] In a first aspect of the present disclosure, a protection circuit is provided. The protection circuit comprises a voltage stabilizing unit. The voltage stabilizing unit comprises a first end adapted to be connected to an output end of a controller. The protection circuit further comprises a filtering unit for filtering a signal and comprising a first end connected to a second end of the voltage stabilizing unit and a second end adapted to be connected to a first end of a sensor. The protection circuit further comprises a cutting unit. The cutting unit comprises a first end connected to a second end of the filtering unit and a second end adapted to be connected to a second end of the sensor and a third end connected to a ground. The voltage stabilizing unit is configured to stabilize the voltage at the output end of the controller at a predetermined voltage when a first voltage applied at the first end of the filtering unit exceeds a predetermined threshold, and the cutting unit is configured to be closed when the first voltage is lower than the predetermined threshold and to be opened when the first voltage is higher than the predetermined threshold.

[0005] In a second aspect of the present disclosure, an electronic control unit is provided. The electronic control unit comprises a controller comprising an output end. The electronic control unit further comprises the protection circuit according to the first aspect of the present disclosure. The anode of the diode of the protection circuit is connected to the output end of the controller.

[0006] In a third aspect of the present disclosure, a vehicle is provided, comprising the electronic control unit according to the second aspect of the present disclosure.

[0007] It is to be understood that the description of the summary section is not intended to identify key or essential features of embodiments of the disclosure or to limit the scope of the disclosure. Other features, aspects, and advantages of the disclosure will become apparent from the following description, which is given by way of example only to provide a thorough understanding of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0008] The above and other features, aspects, and advantages of various embodiments of the present disclosure will become more apparent from the following description as illustrated in the accompanying drawings. In the drawings:

[0009] FIG. 1 illustrates a schematic diagram of an example controller system, according to some embodiments of the present disclosure;

[0010] FIG. 2 illustrates a schematic diagram of an example controller system, according to some embodiments of the present disclosure; and

[0011] FIG. 3 illustrates a schematic diagram of an example controller system, according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0012] Various embodiments are now described with reference to the drawings. In general, the drawings described below are diagrammatic and schematic representations of possible embodiments of the present disclosure. In the drawings, the size of elements can have been exaggerated for clarity, and the like. Further, the drawings are not necessarily to scale, and the emphasis instead is placed upon illustrating the principles of the embodiments. The drawings are not intended to limit the scope of the disclosure in any way.

[0013] Reference throughout this description to "embodiment" or "one embodiment" means that a particular configuration, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. Moreover, the various features of the embodiments can be combined in any suitable manner without necessarily being mutually exclusive, as the above summary is intended to encompass any suitable combination or permutation of the various features.

[0014] In the following disclosure, unless otherwise indicated, when referring to an absolute position modifier such as the terms "front," "back," "top," "bottom," "left," "right," etc., or a relative position modifier such as the terms "above," "below," "higher," "lower," etc., or when referring to an orientation modifier such as "horizontal," "vertical," etc., reference is made to the orientation shown in the figures.

[0015] In the following description, one or more specific details are described to provide an example embodiment of the description. One or more other embodiments can not use the specific details (e.g., can use other components, methods, materials, etc.). Other embodiments can not include all of the features described examples can be implemented to achieve devices, systems, or methods that differ from those described.

[0016] The first challenge in upgrading from a 12-volt system to a 48-volt system is technical compatibility. On the one hand, application-specific integrated circuits designed based on a 12-volt architecture cannot directly withstand 48-volt voltage input in terms of their hardware (such as voltage-resistant circuits and power management modules). If forced to adapt, they are likely to be destroyed by overvoltage or cause system failure. On the other hand, modern automotive electronic systems are highly complex, and a large number of wire harness interfaces and sensor connectors are connected under the influence of long-term vibration, aging, or mechanical stress, and there is a non-negligible risk of short circuit. Once the interface of a 12-volt component accidentally short-circuits with a 48-volt power supply, the instantaneous overvoltage will directly break sensitive electronic components, causing related ECUs to fail and possibly endangering the safety of the entire vehicle.

[0017] Taking a conventional airbag system as an example, the ECU and the sensor that complies with the peripheral sensor interface protocol have a low voltage when working normally. If the PSI communication line accidentally short-circuits with a 48-volt power supply, high voltage will damage both the sensor and the ECU at the same time, causing the entire airbag system to malfunction.

[0018] To achieve a smooth transition from a 12-volt to a 48-volt power supply system and ensure that the ECU system can meet the higher requirements of future vehicles in terms of performance and environmental protection, in-depth research and development must be carried out on existing technologies. This includes designing application-specific integrated circuits with higher voltage resistance, improving power management solutions, and systematically optimizing the entire ECU architecture to adapt to a high-voltage working environment.

[0019] In existing protection technologies, a protection diode can usually be added to the PSI interface of an airbag ECU to deal with such short-circuit risks. However, due to space, cost, or design limitations, PSI sensors located at different positions in the vehicle often cannot be effectively protected in the same way, making them more vulnerable and forming a weak link in the system protection.

[0020] In view of this, embodiments of the present disclosure provide a circuit for protecting a controller and a sensor. The circuit includes a voltage stabilizing unit, a filter unit, and a cutting unit in series between the sensor and the controller. In a normal working state, the controller output voltage is stabilized at a predetermined voltage by the voltage stabilizing unit, and then transmitted to the sensor after filtering out noise by the filter unit. When the voltage at the output end of the filter unit is lower than a predetermined threshold, the cutting unit is closed, the sensor ground loop is turned on, and stable and interference-free signal transmission and work are achieved. Conversely, in the case of overvoltage (such as short circuit with a 48V power supply) in the sensor line, the voltage at the first end of the sensor will exceed the predetermined threshold, and the cutting unit will immediately disconnect after detection, cutting off the sensor ground loop. At the same time, the voltage stabilizing unit can assist in suppressing part of the overvoltage (if the overvoltage comes from the controller side), and double protection is provided for the sensor against overvoltage damage.

[0021] According to embodiments of the present disclosure, the circuit achieves overvoltage protection through voltage stabilization by the voltage stabilizing unit and the protection mechanism of the cutting unit overvoltage protection, solves the problem of quickly cutting off the sensor loop in an abnormal overvoltage scenario, and achieves comprehensive protection of the controller-to-sensor path, especially for scenarios such as automotive electronics, industrial control, and other scenarios that require high voltage stability and overvoltage resistance (such as PSI sensor interface protection).

[0022] FIG. 1 shows a schematic diagram of an example controller system 1 according to some embodiments of the present disclosure. As shown in FIG. 1, the controller system 1 includes an electronic control unit 10. The electronic control unit 10 may, for example, be an airbag ECU of an airbag system. The controller system 1 also includes one or more sensors 20 for data transmission with the control unit 10.

[0023] The protection circuit 100 implements protection by monitoring the voltage on the sensor 20 line. The protection circuit 100 includes a voltage stabilizing unit 110, a filter unit 130, and a cutting unit 120. The first end N11 of the voltage stabilizing unit 110 is connected to the output end N1 of the controller 200, and the second end N12 of the voltage stabilizing unit 110 is connected to the first end N31 of the filter unit 130. The voltage stabilizing unit 110 is capable of stabilizing the voltage at the controller output end N1 at a predetermined voltage when the first voltage applied at the first end N21 of the filter unit 130 exceeds a predetermined threshold. In some embodiments, the predetermined voltage can be the voltage required for normal operation of the sensor 20.

[0024] The first end N31 of the filter unit 130 is connected to the second end of the voltage stabilizing unit 110 to receive signals from the voltage stabilizing unit 110. In addition, the filter unit 130 is capable of filtering the signals output by the controller or transmitted by the sensor to reduce high-frequency noise interference. Subsequently, the second end N32 of the filter unit 130 is connected to the first end N2 of the sensor 20, thereby transmitting the filtered signals to the sensor 20.

[0025] The cut-off unit 120 is a protection execution component of the circuit, which controls the on-off of the loop by detecting the voltage threshold. The first end N21 of the cut-off unit 120 is connected to the second end N32 of the filter unit 130 for detecting the voltage of the node. The second end N22 of the cut-off unit 120 is connected to the second end N3 of the sensor 20, and the third end N23 of the cut-off unit 120 is grounded.

[0026] In some embodiments, when the first voltage (the voltage of the first end N2 of the sensor 20) is less than a predetermined threshold (such as the normal working 12V or 36V system voltage range), the cut-off unit 120 is closed, the ground loop of the sensor 20 is conducted, and the entire controller system 1 is ensured to work normally. When the first end N2 of the sensor 20 is short-circuited to the voltage source 30 with a voltage higher than the predetermined threshold, i.e., the first voltage is higher than the predetermined threshold (such as a 48V short circuit occurs), the cut-off unit 120 is opened, and the ground loop of the sensor 20 is cut off to avoid damage caused by overvoltage forming a loop through the sensor. On the other hand, when the first voltage is higher than the predetermined threshold, the voltage at the output end N1 of the controller 200 is stabilized at the predetermined voltage by the voltage stabilization unit, so that it does not exceed the bearable range of the controller, thereby avoiding damage to the controller. It should be understood that the high voltage 48V higher than the predetermined threshold mentioned in the present disclosure is only exemplary. The high voltage can be any other voltage higher than the predetermined threshold.

[0027] According to the embodiment shown in FIG. 1, the combination of the voltage stabilization effect of the voltage stabilization unit and the threshold control of the cut-off unit achieves bidirectional overvoltage protection for the controller and the sensor. For example, when a short circuit with a voltage higher than the bearable voltage occurs at the sensor interface, neither the controller nor the sensor will be damaged by overvoltage, ensuring their reliable operation in a high-voltage scenario and avoiding the paralysis of the entire vehicle electronic system due to ECU failure.

[0028] FIG. 2 shows a schematic diagram of an example controller system 1 according to some embodiments of the present disclosure. As shown in FIG. 2, the controller system 1 includes an electronic control unit 10, one or more sensors 20 for data transmission with the control unit 10. The voltage stabilization unit 110 includes an N-type metal oxide semiconductor field effect transistor (NMOS) Q3 (also referred to as a first NMOS). The source of the NMOS Q3 is connected to the first end N11 of the voltage stabilization unit 110. The drain of the NMOS Q3 is connected to the second end N12 of the voltage stabilization unit 110. The gate of the NMOS Q3 is connected to a driving unit 140 configured to provide a voltage associated with a predetermined voltage.

[0029] According to the working principle of the source follower of the NMOS, when the drain voltage of the NMOS Q3 is higher than the gate voltage, the source voltage will follow the gate voltage and keep a fixed offset voltage. The offset is the threshold voltage between the gate and the source of the NMOS. Therefore, the stable value of the source voltage of the NMOS Q3 is about the gate voltage minus the threshold voltage between the gate and the source. The resulting source voltage is the "predetermined voltage" to be stabilized. For a conducting NMOS, the source voltage is equal to the drain voltage. In such embodiments, compared with the conventional zener diode, the NMOS has a small resistance when conducting, can provide a much larger current than the zener diode, has little effect on the output voltage, and has a better voltage stabilizing effect. In addition, the predetermined stable voltage is no longer determined by a fixed breakdown voltage, but by the accurate control provided by the driving unit. This provides great design flexibility. That is, the "predetermined voltage" can be adjusted by changing the output of the driving unit 140.

[0030] The first end N31 of the filter unit 130 is connected to the second end of the voltage stabilizing unit 110, and the second end N32 is connected to the first end N2 of the sensor 20 and the first end N21 of the cut-off unit 120. In some embodiments, the filter unit 130 can include an RC circuit formed by a resistor and a capacitor, or an LC circuit formed by an inductor and a capacitor. In such embodiments, the filter unit 130 can filter out high-frequency noise and glitches in the signal line.

[0031] The first end N21 of the cut-off unit 120 is connected to the second end N32 of the filter unit 130 and the first end N2 of the sensor 20 as a voltage detection point. The second end N22 of the cut-off unit 120 is connected to the second end N3 of the sensor 20. Generally, the second end of the sensor 20 is a ground path. The third end N23 of the cut-off unit 120 is directly connected to the ground.

[0032] As shown in FIG. 2, the cut-off unit 120 includes an NMOS Q1 (also referred to as a second NMOS) and a control module 121. The source of the NMOS Q1 is connected to the third end N23 of the cut-off unit 120. The drain of the NMOS Q1 is connected to the second end N22 of the cut-off unit 120. In addition, the cut-off unit 120 also includes a control module 121. The control module 121 controls the on-off of the ground return circuit of the sensor 20 under its control. The first end N24 of the control module 121 is connected to the first end N21 of the cut-off unit 120, i.e., the detection voltage node. The control module 121 thereby receives the signal from the first end of the sensor to control the closing / opening of the NMOS Q1 according to the signal. The control module 121 outputs a control signal according to the first voltage. The second end N25 of the control module 121 is connected to the gate of the NMOS Q1 to output the control signal.

[0033] In operation, when the control module 121 detects that the first voltage is below a predetermined threshold, the control module 121 outputs a first control signal, such as a high level, to close the NMOS Q1. When the first voltage is above the predetermined threshold, the control module 121 outputs a second control signal, such as a low level, to open the NMOS Q1. To implement the corresponding control logic, the control module 121 includes a switch 122. The first end of the switch 122 is connected to the second end N25 of the control module, i.e., the gate of the NMOS Q1. The control end of the switch 122 is connected to the first end N24 of the control module 121, i.e., the detection voltage node. The second end of the switch 122 is grounded.

[0034] In the illustrated embodiment, the switch 122 can change the control end voltage of the NMOS Q1 by itself on-off. When the first voltage is below the predetermined threshold, the switch 122 is opened, and the gate of the NMOS Q1 is connected to the driving unit 140. The driving unit 140 as a voltage source provides a high level first control signal to the gate of the NMOS Q1 through the first end, so as to close the NMOS Q1. When the first voltage is above the predetermined threshold, the switch 121 is closed, and the control end of the NMOS Q1 is pulled to the ground level second control signal, so as to open the NMOS Q1.

[0035] In some embodiments, when the first voltage N32 node voltage is less than a predetermined threshold, such as a normal working 36V system voltage range, the cut-off unit 120 is closed, the sensor 20 ground loop is turned on, and normal working is ensured. In contrast, when the first voltage is higher than the predetermined threshold, such as a 48V short circuit, the cut-off unit is opened, and the sensor ground loop is cut off to avoid overvoltage forming a loop through the sensor and causing damage.

[0036] FIG. 3 shows a schematic diagram of an example controller system according to some embodiments of the present disclosure. As shown in FIG. 3, the controller system 1 includes an electronic control unit 10 and one or more sensors 20 for data transmission with the control unit 10. The one or more sensors 20 may, for example, be PSI sensors with an interface complying with the PSI protocol.

[0037] The electronic control unit 10 includes a controller 200 and a protection circuit 100. The controller 200 may, for example, be a processing chip. As shown in FIG. 3, the controller 200 includes complementary MOS circuits, i.e., NMOS M1 and M2 with their sources connected to each other. The gates of the two NMOS are used to receive control signals, such as synchronous pulse signals.

[0038] The protection circuit 100 comprises a voltage stabilizing unit 110. The voltage stabilizing unit 110 comprises an NMOS Q3. The source of the NMOS Q3 is connected to a first terminal N11 of the voltage stabilizing unit 110. The drain of the NMOS Q3 is connected to a second terminal N12 of the voltage stabilizing unit 110. The gate of the NMOS Q3 is connected to a driving unit 140 configured to provide a voltage associated with a predetermined voltage. The voltage stabilizing unit 110 further comprises a capacitor C3 and a resistor R11. The capacitor C3 and the resistor R11 are connected in parallel between the source and the gate of the NMOS Q3.

[0039] The driving unit 140 comprises a voltage source V1, a transistor Q4 (also referred to as a first transistor), a diode D2 (also referred to as a first diode), a diode D3 (also referred to as a second diode), a resistor R9 (also referred to as a first resistor) and a resistor R10 (also referred to as a second resistor). The collector of the transistor Q4 is connected to the first terminal of the resistor R10 and the voltage source V1. The base of the transistor Q4 is connected to the second terminal of the resistor R10 and the cathode of the diode D2. The anode of the first diode D2 is connected to ground. The emitter of the transistor Q4 is connected to the anode of the second diode D3. The cathode of the diode D3 is connected to the first terminal of the second resistor R10, and the second terminal of the second resistor R10 is connected to the gate of the NMOS Q3.

[0040] The driving unit 140 is a constant voltage source based on a transistor. The driving unit 140 is capable of providing a stable driving voltage to the gate of the NMOS Q3, which is associated with the "predetermined voltage". In this driving unit 140, the current flows out of the voltage source V1 and is divided into two paths: one path enters the collector of the transistor Q4, and the other path passes through the resistor R10. Then, the voltage at the base of the transistor Q4 is defined on a first defined voltage by the voltage stabilizing diode D2, and then defined on a second defined voltage V2 by the diode D3. The second defined voltage V2 is provided to the gate of the NMOS Q3 via the resistor R9. On the other hand, the second defined voltage V2 is provided to the cutting unit 120.

[0041] In addition, the driving unit 140 further comprises a resistor R7 (also referred to as a third resistor) and a resistor R8 (also referred to as a fourth resistor). The first terminal of the resistor R7 is connected to the cathode of the diode D3 and the first terminal of the resistor R10. The second terminal of the resistor R7 is connected to the first terminal of the resistor R8. The second terminal of the resistor R8 is connected to ground. In this embodiment, the current I at the second terminal of the resistor R7 is detected for determining the state of the protection circuit 100.

[0042] The filter unit 130 is an RC filter network. The filter unit 130 includes a capacitor C1 (also referred to as a third capacitor), a resistor R1 (also referred to as a fifth resistor), and a capacitor C2 (also referred to as a fourth capacitor). A first end of the capacitor C1 is connected to a first end of the filter unit 130 and a first end of the resistor R1, and a second end of the capacitor C1 is grounded. A second end of the third resistor R1 of the filter unit 130 is connected to a second end of the filter unit 130 and a first end of the capacitor C2. A second end of the capacitor C2 of the filter unit 130 is grounded.

[0043] In the embodiment shown in FIG. 3, the capacitor C1, the resistor R1, and the capacitor C2 constitute a "pi" type RC filter circuit. For example, the capacitor C1 can filter high-frequency noise in the signal present at the input end, i.e., on the filter unit 130. The resistor R1 can achieve current limiting and damping, and cooperate with the capacitor C1 and the capacitor C2 to suppress high-frequency resonance, while also playing a protective role in the event of overcurrent. The capacitor C2 can further filter residual noise, and ultimately output a smooth signal to the sensor 20, reducing the interference of noise on the sensor and subsequent circuits. In such an embodiment, by providing a pi type filter, the filtering effect on different frequency bands of noise can be enhanced, and signal integrity can be improved.

[0044] The cut-off unit 120 includes an NMOS Q1. A source of the NMOS Q1 is connected to ground. A drain of the NMOS Q1 is connected to a second end N22 of the sensor 20. In addition, the circuit module corresponding to the control module 121 in FIG. 2 includes a transistor Q2, a resistor R2 (also referred to as a third resistor), a resistor R3 (also referred to as a fourth resistor), a voltage stabilizing diode D2, a resistor R4, a resistor R5, and a resistor R6. The circuit module corresponding to the second switch 122 of the control module 121 includes: the transistor Q2, the resistor R2, and the resistor R3. A first end of the first resistor R2 corresponds to a control end of the second switch 122, and is connected to a first end of the sensor 20. A second end of the first resistor R2 is connected to a first end of the second resistor R3 and a base of the transistor Q2. A second end of the second resistor R3 is connected to ground. A collector of the transistor Q2 corresponds to a first end of the second switch 122. An emitter of the transistor Q2 is a second end of the second switch 122. In addition, the circuit module corresponding to the second switch 122 of the control module 121 further includes a capacitor C4. A first end of the capacitor C4 is connected to the base of the transistor Q2, and a second end of the first capacitor C4 is connected to ground.

[0045] The circuit module corresponding to the control module 121 in FIG. 2 can also include a voltage stabilizing circuit. The voltage stabilizing circuit includes a voltage stabilizing diode D2, a resistor R5, and a resistor R6. A first end of the resistor R6 is connected to the second end N32 of the filter unit 130. The cathode of the voltage stabilizing diode D2 is connected to a second end of the resistor R6 and a first end of the resistor R5, and the anode of the voltage stabilizing diode D2 is connected to a first end of the resistor R2 and a second end of the resistor R5. That is, the voltage stabilizing diode D2 is connected in series to the line between the filter unit 130 and the sensor 20. In this way, when the first end of the sensor 20 is shorted to a high voltage, the voltage stabilizing diode D2 can limit the high voltage to a fixed voltage value, which helps the design of the subsequent circuit and improves the stability of the circuit.

[0046] In this embodiment, the NMOS Q1 controls the ground loop of the sensor 20. The gate is controlled by the transistor Q2, and the source of the NMOS Q1 is grounded, and the drain is connected to the ground end of the sensor. In normal operation, since the interface voltage of the sensor 20 is below the threshold value, and the voltage division of the resistor R2 and the resistor R3 is not enough to turn on the transistor Q2, Q2 is off. The voltage V1 makes the NMOS Q1 gate receive a high level through R4, so that the voltage between the gate and the source of the NMOS Q1 is higher than the voltage threshold, so that the NMOS Q1 is turned on, and the sensor ground loop is normal. Conversely, when the interface voltage of the sensor 20 exceeds the threshold value, the high voltage reaches the base of the transistor Q2 after being limited by the voltage stabilizing diode D2 and divided by the resistor R2 and the resistor R3, so that the transistor Q2 is turned on. In this way, the NMOS Q1 gate is pulled low, so that the voltage between the gate and the source of the NMOS Q1 is less than the voltage threshold, i.e., the turn-on condition is no longer met, so that the NMOS Q1 is turned off, cutting off the sensor ground loop and forming a high-impedance state, thereby protecting the sensor 20. The working principle of the entire sensor system will be described below as a whole.

[0047] In a normal state, the control signal S (such as a synchronization pulse signal) of the controller 200 triggers the conduction of MOS M1 and M2, and the power supply V3 outputs. The NMOS Q3 is turned on, and the signal is transmitted to the sensor 20 after being filtered by RC. At this time, since the voltage at the base of the transistor Q2 is not enough to turn it on, the transistor Q2 is off. As discussed above, the NMOS Q1 is turned on, the sensor ground loop is normal, and the system works stably.

[0048] In case of overvoltage fault, for example, the first end of sensor 20 is shorted to 48V short circuit, the voltage at the first end of sensor 20 as the first voltage rises sharply, the voltage divider of resistor R2 and resistor R3 makes the transistor Q2 conduct, pulls down the voltage of the gate of NMOS Q1, NMOS Q1 is cut off, and the sensor ground loop is cut off. At the same time, the gate voltage of NMOS Q3 is stabilized at the voltage provided by the driving unit 140, so that the voltage of the source of NMOS Q3, that is, the output end of the controller, is clamped at a predetermined voltage, avoiding the voltage at the control unit being too high. Finally, both the sensor and the control unit are in a protection state, avoiding overvoltage damage.

[0049] According to the embodiment shown in FIG. 3, the protection circuit 100 realizes reliable protection of the sensor interface, for example, in the vehicle 12V / 48V voltage upgrade scenario, through the multi-layer protection of voltage stabilization at a predetermined voltage value, RC filtering, and threshold cut-off, while taking into account signal integrity and device safety.

[0050] Without impairing the basic principles, the details and embodiments can vary, even significantly, with respect to what is described by way of example only, without departing from the scope of protection. The various embodiments described above can be combined to provide further embodiments. If the concepts of various patents, applications and publications need to be adopted to provide further embodiments, aspects of the embodiments can be modified.

[0051] These and other changes can be made to the embodiments in light of the above detailed description. In general, the terms used in the following claims should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Therefore, the claims are not limited by the disclosure.

Claims

1. A protection circuit (100), comprising: a voltage stabilizing unit (110) comprising a first terminal (N11) adapted to be connected to an output terminal (N1) of a controller (200); a filtering unit (130) for filtering a signal and comprising a first terminal (N31) connected to a second terminal (N12) of the voltage stabilizing unit (110) and a second terminal (N32) adapted to be connected to a first terminal (N2) of a sensor (20); and a cutting unit (120) comprising a first terminal (N21) connected to the second terminal (N32) of the filtering unit (130) and a second terminal (N22) adapted to be connected to a second terminal (N3) of the sensor (20) and a third terminal (N23) connected to ground, wherein the voltage stabilizing unit (110) is configured to stabilize a voltage at the output terminal (N1) of the controller (200) at a predetermined voltage when a first voltage applied at the first terminal (N21) of the filtering unit (130) exceeds a predetermined threshold, and the cutting unit (120) is configured to be closed in case the first voltage is lower than the predetermined threshold and to be opened in case the first voltage is higher than the predetermined threshold.

2. The protection circuit (100) according to claim 1, wherein the voltage stabilizing unit (110) comprises: a first N-type metal oxide semiconductor field effect transistor (NMOS), wherein a source of the first NMOS is connected to the first terminal (N11) of the voltage stabilizing unit (110), a drain of the first NMOS is connected to the second terminal (N12) of the voltage stabilizing unit (110), and a gate of the first NMOS is connected to a driving unit (140) configured to provide a voltage associated with the predetermined voltage.

3. The protection circuit (100) according to claim 2, wherein the driving unit (140) comprises: a voltage source (V1), a first transistor (Q4), a first diode (D2), a second diode (D3), a first resistor (R9), and a second resistor (R10), wherein a collector of the first transistor (Q4) is connected to a first terminal of the second resistor (R10) and the voltage source (V1), a base of the first transistor (Q4) is connected to a second terminal of the second resistor (R10) and a cathode of the first diode (D2), an anode of the first diode (D2) is connected to ground, an emitter of the first transistor (Q4) is connected to an anode of the second diode (D3), a cathode of the second diode (D3) is connected to the first terminal of the second resistor (R10), and a second terminal of the second resistor (R10) is connected to the gate of the first NMOS.

4. The protection circuit (100) according to claim 3, the driving unit (140) further comprising: ​ a third resistor (R7) and a fourth resistor (R8), wherein a first end of the third resistor (R7) is connected with the cathode of the second diode (D3) and the first end of the second resistor (R10), a second end of the third resistor (R7) is connected with a first end of the fourth resistor (R8), and a second end of the fourth resistor (R8) is connected with ground, wherein a current at the second end of the third resistor (R7) is detected for determining a state of the protection circuit (100).

5. The protection circuit (100) according to claim 1, wherein the cut-off unit (120) comprises: a second NMOS, wherein a source of the second NMOS is connected with the third end (N23) of the cut-off unit (120), and a drain of the second NMOS is connected with the second end (N22) of the cut-off unit (120); and a control module (121) comprising a first end (N24) connected with a first end (N21) of the cut-off unit (120) and a second end (N25) connected with a gate of the second NMOS, wherein the control module (121) is configured to send a first control signal indicating closing to the gate of the second NMOS if the first voltage is lower than a predetermined threshold, and to send a second control signal indicating opening to the gate of the second NMOS if the first voltage is higher than the predetermined threshold.

6. The protection circuit (100) according to claim 5, wherein the control module (121) comprises: a switch (122) comprising a first end connected with the second end (N28) of the control module (121) and a voltage source, a control end connected with the first end (N27) of the control module (121), and a second end connected with ground, wherein the switch (122) is configured to be opened if a voltage applied at the second end (N22) of the cut-off unit (120) is lower than a predetermined threshold, so that the control module (121) sends the first control signal, and to be closed if the voltage applied at the second end (N22) is higher than the predetermined threshold, so that the control module (121) sends the second control signal.

7. The protection circuit (100) according to claim 6, wherein the switch (122) comprises: a triode (Q1), a third resistor (R2), and a fourth resistor (R3), wherein a first end of the third resistor (R2) is the control end of the switch (122), a second end of the third resistor (R2) is connected with a first end of the fourth resistor (R3) and a base of the triode (Q1), a second end of the fourth resistor (R3) is connected with ground, a collector of the triode (Q1) is the first end of the switch (122), and an emitter of the triode (Q1) is the second end of the switch (122).

8. The protection circuit (100) according to claim 1, further comprising: a zener diode (D2), wherein a cathode of the zener diode (D2) is connected to the second end (N32) of the filter unit (130), and an anode of the zener diode (D2) is connected to the first end (N21) of the cut-off unit (120).

9. The protection circuit (100) according to claim 1, wherein the filter unit (130) comprises: a third capacitor (C1), a fifth resistor (R1), a fourth capacitor (C2), wherein a first end of the third capacitor (C1) is connected to a first end of the filter unit (130), a first end of the fifth resistor (R1), a second end of the third capacitor (C1) is connected to ground, a first end of the fourth capacitor (C2) is connected to the second end of the filter unit (130), and a second end of the fourth capacitor (C2) is connected to the third end of the filter unit (130) and to ground.

10. An electronic control unit (10) comprising: a controller (200) comprising an output (N1); and a protection circuit (100) according to any one of claims 1 to 9, wherein a first end of the zener unit (110) of the protection circuit (100) is connected to the output (N1) of the controller (200).

11. The electronic control unit (10) according to claim 10, wherein the output (N1) comprised by the controller (200) complies with the Peripheral Sensor Interface, PSI, protocol.

12. A vehicle comprising the electronic control unit (10) according to claim 10 or 11. ​

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