Preceding-stage input protection circuit and afterloading vehicle
By introducing a pre-amplifier input protection circuit into aftermarket vehicles and utilizing a combination of various components, the interference problem at the power input end of aftermarket vehicles is solved, ensuring stable and reliable operation of the equipment and preventing equipment damage.
Patent Information
- Application Number
- CN202423323372.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2034-12-31
AI Technical Summary
Additional electronic equipment installed in aftermarket vehicles can cause problems such as overvoltage and surges at the power input, which may lead to abnormal operation or even burnout of the equipment.
It adopts a front-end input protection circuit, including a front-end transient voltage suppression unit, a first reverse protection unit, a second reverse protection unit, and a DC-DC unit. Through components such as bidirectional TVS transistors, power NMOS transistors, common-mode inductors, and over/under voltage units, it provides stable and reliable power protection.
It effectively suppresses interference at the power input terminal, prevents reverse connection of the positive and negative terminals of the equipment and reverse power flow, ensures the stability and reliability of the subsequent circuits, and protects sensitive components from common-mode noise and over-voltage/under-voltage effects.
Smart Images
Figure CN223942592U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power management technology, and more specifically, to a pre-amplifier input protection circuit and its application in aftermarket vehicles. Background Technology
[0002] Aftermarket vehicles refer to those that have undergone additional modifications or have equipment added after leaving the factory, based on specific engineering or operational needs. The equipment used in aftermarket vehicles is powered by the vehicle's battery. Depending on the customer's specific requirements, different electronic devices, such as air conditioning and headlights, are added to the battery. During actual use, these additional electronic devices may cause greater interference at the power input compared to the original vehicle, such as overvoltage and surges. In severe cases, this can lead to equipment malfunctions or even burnout. Utility Model Content
[0003] The purpose of this application is to provide a pre-amplifier input protection circuit and an aftermarket vehicle, so as to provide a stable and reliable power supply for the equipment in the aftermarket vehicle.
[0004] In a first aspect, this application provides a front-end input protection circuit for use in aftermarket vehicles, comprising a front-end transient voltage suppression unit, a first anti-reverse unit, a second anti-reverse unit, and a DC-DC converter unit; the input terminal of the front-end transient voltage suppression unit is connected to an external power supply, the output terminal of the front-end transient voltage suppression unit is connected to the input terminal of the first anti-reverse unit, the output terminal of the first anti-reverse unit is connected to the input terminal of the second anti-reverse unit and is used to connect to a subsequent drive circuit, the output terminal of the second anti-reverse unit is connected to the input terminal of the DC-DC converter unit, and the output terminal of the DC-DC converter unit is used to connect to a subsequent control circuit.
[0005] In the above scheme, when the equipment is installed on the aftermarket vehicle, the first reverse polarity protection unit can stop the downstream drive circuit from operating until normal connection is restored if the positive and negative terminals of the equipment are reversed. Furthermore, when the aftermarket equipment is communicating with external systems, the second reverse polarity protection unit can prevent power backflow and stop the downstream control circuit from operating until normal connection is restored if the positive and negative terminals of the equipment are reversed. Moreover, the two-stage reverse polarity protection circuit can provide more adaptable protection for different downstream circuits under varying operating conditions. The front-end transient voltage suppression unit can improve the anti-interference capability of the front-end input protection circuit, enabling it to effectively suppress surges and interference, thus providing a more stable and reliable power supply for the downstream circuits.
[0006] As an optional approach, the front-end transient voltage suppression unit includes a bidirectional TVS diode; one end of the bidirectional TVS diode is connected to the external power supply and the input terminal of the first reverse protection unit, and the other end of the bidirectional TVS diode is connected to the isolation ground.
[0007] In the above scheme, the use of a bidirectional TVS diode can quickly respond to and clamp the voltage, protecting the circuit from voltage transients such as electrostatic discharge and power surges.
[0008] As an optional embodiment, the first anti-reverse unit includes a first power NMOS transistor, a first resistor, a second resistor, a first capacitor, and a first diode; the gate of the first power NMOS transistor is connected to one end of the first resistor, the other end of the first resistor is connected to the output terminal of the front-end transient voltage suppression unit and the input terminal of the second anti-reverse unit, the drain of the first power NMOS transistor is connected to isolation ground, the source of the first power NMOS transistor is connected to the anode of the first diode, one end of the second resistor, one end of the first capacitor, and power ground, and the cathode of the first diode, the other end of the second resistor, and the other end of the first capacitor are connected to the gate of the first power NMOS transistor.
[0009] In the above scheme, the use of a first power NMOS transistor can effectively prevent reverse current from flowing through the subsequent drive circuit.
[0010] As an optional approach, the second anti-reverse unit includes a second diode and a second capacitor; the anode of the second diode is connected to the output terminal of the first anti-reverse unit, the cathode of the second diode is connected to one end of the second capacitor and the input terminal of the DC-DC unit, and the other end of the second capacitor is grounded.
[0011] In the above scheme, using a second diode can achieve its anti-reverse function stably and reliably while simply realizing the second anti-reverse unit.
[0012] As an optional approach, a common-mode rejection unit is also included, used to suppress common-mode interference in the external power supply before outputting it to the DC-DC unit. In the above scheme, the common-mode rejection unit can suppress common-mode interference present at the power input terminal, reducing the impact of common-mode interference on the back-end circuitry.
[0013] As an optional approach, the first anti-reverse unit is connected to the second anti-reverse unit through the common-mode suppression unit. The common-mode suppression unit includes a common-mode inductor; the first input terminal of the common-mode inductor is connected to the output terminal of the first anti-reverse unit, the second input terminal of the common-mode inductor is connected to the power supply ground, the first output terminal of the common-mode inductor is connected to the input terminal of the second anti-reverse unit, and the second output terminal of the common-mode inductor is grounded.
[0014] In the above scheme, a common-mode inductor is used to implement the common-mode suppression unit, which can effectively suppress common-mode interference on power lines or signal lines, protect sensitive components in the circuit from common-mode noise, and provide a stable and reliable power supply for subsequent circuits.
[0015] As an optional approach, an over / under voltage protection unit is also included for over / under voltage protection of the circuit. In the above solution, the over / under voltage protection unit can prevent the circuit from being damaged due to excessively high or low voltage, thereby protecting sensitive components in the circuit.
[0016] As an optional configuration, the second anti-reverse unit is connected to the DC-DC unit via the over / under voltage unit. The over / under voltage unit includes a third diode, a fourth diode, a fifth diode, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second power NMOS transistor, a third power NMOS transistor, a power PMOS transistor, a third capacitor, and a fourth capacitor. The gate of the second power NMOS transistor is connected to one end of the third resistor and one end of the fourth resistor. The other end of the third resistor is connected to the anode of the third diode, and the other end of the fourth resistor is grounded. The drain of the second power NMOS transistor is connected to one end of the fifth resistor, one end of the sixth resistor, one end of the third capacitor, and the gate of the third power NMOS transistor. The other end of the fifth resistor... One end of the resistor is connected to the anode of the fourth diode, the other end of the sixth resistor and the other end of the third capacitor are grounded, the cathodes of the third diode and the fourth diode are connected to the output terminal of the second anti-reverse unit, and the source of the second power NMOS transistor is grounded; the drain of the third power NMOS transistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the fourth capacitor, one end of the eighth resistor, the anode of the fifth diode and the gate of the power PMOS transistor, the other end of the fourth capacitor, the other end of the eighth resistor, the cathode of the fifth diode and the source of the power PMOS transistor are connected to the output terminal of the second anti-reverse unit, and the source of the third power NMOS transistor is grounded; the drain of the power PMOS transistor is connected to the input terminal of the DC-DC unit.
[0017] In the above scheme, power NMOS transistors and power PMOS transistors are used to implement the over- and under-voltage unit, which can provide a stable and reliable power supply for the subsequent circuits.
[0018] Alternatively, the third and fourth diodes may include Zener diodes. In the above scheme, using Zener diodes to implement the over / under voltage unit enables precise voltage clamping, providing reliable over / under voltage protection for the circuit.
[0019] Secondly, this application provides an aftermarket vehicle that includes the front-stage input protection circuit described in the first aspect.
[0020] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing embodiments of this application. Attached Figure Description
[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 A schematic diagram of a pre-amplifier input protection circuit provided in an embodiment of this application;
[0023] Figure 2 A circuit connection diagram of a front-end transient voltage suppression unit provided in an embodiment of this application;
[0024] Figure 3 A circuit connection diagram of a first anti-reverse unit provided in an embodiment of this application;
[0025] Figure 4 A circuit connection diagram of a second anti-reverse unit provided in an embodiment of this application;
[0026] Figure 5 A circuit connection diagram of a common-mode suppression unit provided in an embodiment of this application;
[0027] Figure 6 A circuit connection diagram of an over / under voltage unit provided in an embodiment of this application;
[0028] Figure 7 A circuit connection diagram of a DC-DC unit provided in an embodiment of this application;
[0029] Figure 8 This application provides a schematic diagram of another pre-amplifier input protection circuit. Detailed Implementation
[0030] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.
[0031] It should be noted that all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.
[0032] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.
[0033] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.
[0034] Reference Figure 1 , Figure 1 This application provides a schematic diagram of a front-end input protection circuit, which is applied to aftermarket vehicles. The circuit includes a front-end transient voltage suppression unit 10, a first anti-reverse unit 20, a second anti-reverse unit 30, and a DC-DC converter unit 40. The input terminal of the front-end transient voltage suppression unit 10 is connected to an external power supply. The output terminal of the front-end transient voltage suppression unit 10 is connected to the input terminal of the first anti-reverse unit 20. The output terminal of the first anti-reverse unit 20 is connected to the input terminal of the second anti-reverse unit 30 and is used to connect to a subsequent drive circuit. The output terminal of the second anti-reverse unit 30 is connected to the input terminal of the DC-DC converter unit 40, and the output terminal of the DC-DC converter unit 40 is used to connect to a subsequent control circuit.
[0035] The main function of the front-end transient voltage suppression unit 10 is to protect the circuit from transient voltage spikes. Transient voltage spikes may be caused by a variety of factors, including: surges on the power line (such as lightning strikes, power switching, etc.), electrostatic discharge, switching noise in the circuit, or switching of inductive loads.
[0036] Considering the possibility of reverse connection between the positive and negative power input terminals when the actual equipment is installed on a retrofitted vehicle, the front-stage input protection circuit is designed with a first reverse connection protection unit 20 connected to the rear-stage drive circuit. During prolonged reverse connection, the equipment will not operate and will not affect other equipment. After restoring the normal connection, the equipment will function normally. Because the current in the drive circuit is relatively large (exceeding 10A), the first reverse connection protection unit 20 is specifically designed to prevent reverse connection issues caused by high current.
[0037] Considering the need for protocol communication and serial port debugging between the actual device and external devices, the first reverse protection unit 20 might cause power backflow during information exchange. Therefore, the front-end input protection circuit is designed with a second reverse protection unit 30 to prevent power backflow. Furthermore, the second reverse protection unit 30 is connected to the subsequent control circuit. When the positive and negative terminals of the power input are reversed, the device will not operate and will not affect other devices. After restoring the normal connection, the device will operate normally. Since the current in the control circuit is smaller than the current in the drive circuit, the second reverse protection unit 30 is specifically designed for preventing reverse current flow.
[0038] The first anti-reverse unit 20 and the second anti-reverse unit 30 can be either positive or negative anti-reverse. In one implementation, the first anti-reverse unit 20 is negative anti-reverse, and the second anti-reverse unit 30 is positive anti-reverse.
[0039] The DCDC unit 40, or DC-DC to DC-DC converter unit, converts the input DC voltage into the required output voltage. It can be a boost converter, a buck converter, or a buck-boost converter. The external power supply, after being processed by the front-end transient voltage suppression unit 10, the first reverse voltage protection unit 20, and the second reverse voltage protection unit 30, can effectively suppress surges and other interference, making the output voltage of the DCDC unit 40 more stable and reliable. This, in turn, ensures that the connected load equipment can operate more stably under different vehicle operating conditions.
[0040] In the above scheme, when the equipment is installed on the aftermarket vehicle, the first reverse polarity protection unit 20 can stop the downstream drive circuit from working until normal connection is restored when the positive and negative terminals of the equipment are reversed. Furthermore, when the aftermarket equipment is communicating with external systems, the second reverse polarity protection unit 30 can prevent power backflow and stop the downstream control circuit from working until normal connection is restored when the positive and negative terminals of the equipment are reversed. Moreover, the two-stage reverse polarity protection circuit can provide more adaptable protection for different downstream circuits under different operating conditions. The front-end transient voltage suppression unit 10 can improve the anti-interference capability of the front-end input protection circuit, enabling it to effectively suppress surges and interference, providing a more stable and reliable power supply for the downstream circuits.
[0041] In some embodiments, such as Figure 2 As shown, Figure 2 This is a circuit connection diagram of a front-end transient voltage suppression unit provided in an embodiment of this application. The front-end transient voltage suppression unit 10 includes a bidirectional TVS diode 101; one end of the bidirectional TVS diode 101 is connected to an external power supply and the input terminal of the first anti-reverse unit 20, and the other end of the bidirectional TVS diode 101 is connected to an isolation ground.
[0042] The external power supply contains static electricity, surges, etc. The front-end transient voltage suppression unit 10 uses a bidirectional TVS diode 101 to suppress transient voltages. It can quickly respond to voltage changes and provide protection for subsequent circuits, avoiding damage to the equipment due to voltage surges.
[0043] Considering the greater complexity of aftermarket automotive applications and the fact that battery voltages are typically 12 / 24V, the rated operating voltage of the bidirectional TVS diode 101 can be selected as 36V. This bidirectional TVS diode 101 can handle high-energy peak pulses in the time range of 10 microseconds (µs) to 150 milliseconds (ms). In actual testing, the front-end transient voltage suppression unit 10 underwent a more rigorous transient conducted immunity-power line test, namely the Pulse 5a test, during which the transient voltage peak value... =+202V, pulse duration =350ms, internal resistance used =2Ω, pulse application times are 10, and the front-end transient voltage suppression unit 10 can also be protected from damage during actual use, ensuring the reliability and stability of the circuit.
[0044] In the above scheme, the bidirectional TVS diode 101 can quickly respond to and clamp the voltage, protecting the circuit from voltage transients such as electrostatic discharge and power surge.
[0045] In some embodiments, refer to Figure 3 , Figure 3 This is a circuit connection diagram of a first anti-reverse unit provided in an embodiment of this application.
[0046] The first anti-reverse unit 20 includes a first power NMOS transistor 201, a first resistor 202, a second resistor 203, a first capacitor 204, and a first diode 205. The gate of the first power NMOS transistor 201 is connected to one end of the first resistor 202, and the other end of the first resistor 202 is connected to the output terminal of the front-end transient voltage suppression unit 10 and the input terminal of the second anti-reverse unit 30. The drain of the first power NMOS transistor 201 is connected to the isolation ground, and the source of the first power NMOS transistor 201 is connected to the anode of the first diode 205, one end of the second resistor 203, one end of the first capacitor 204, and the power supply ground. The cathode of the first diode 205, the other end of the second resistor 203, and the other end of the first capacitor 204 are connected to the gate of the first power NMOS transistor 201.
[0047] In the above scheme, the use of the first power NMOS transistor 201 can effectively prevent reverse current in the subsequent drive circuit.
[0048] In some embodiments, the first diode 205 includes a Schottky diode.
[0049] In the above scheme, using a Schottky diode can make the first anti-reverse unit 20 respond faster and be more efficient.
[0050] In some embodiments, refer to Figure 4 , Figure 4 This is a circuit connection diagram of a second anti-reverse unit provided in an embodiment of this application. The second anti-reverse unit 30 includes a second diode 301 and a second capacitor 302; the anode of the second diode 301 is connected to the output terminal of the first anti-reverse unit 20, the cathode of the second diode 301 is connected to one end of the second capacitor 302 and the input terminal of the DC-DC unit 40, and the other end of the second capacitor 302 is grounded.
[0051] In the above scheme, the use of the second diode 301 can achieve its anti-reverse function stably and reliably while simply implementing the second anti-reverse unit 30.
[0052] In some embodiments, the pre-amplifier input protection circuit further includes a common-mode rejection unit 50, which is used to suppress common-mode interference from the external power supply and then output it to the DC-DC unit 40.
[0053] Because the vehicle battery has a complex high-frequency switching controller, such as an aftermarket motor, there will be common-mode interference at the external power input. Therefore, a common-mode suppression unit 50 is added to suppress common-mode interference.
[0054] In the above scheme, the common-mode rejection unit 50 can suppress common-mode interference present in the power input terminal and reduce the impact of common-mode interference on the back-end circuit.
[0055] In some embodiments, refer to Figure 5 , Figure 5 This is a circuit connection diagram of a common-mode suppression unit provided in an embodiment of this application. The first anti-reverse unit 20 is connected to the second anti-reverse unit 30 through the common-mode suppression unit 50. The common-mode suppression unit 50 includes: a common-mode inductor 501; the first input terminal 1 of the common-mode inductor 501 is connected to the output terminal of the first anti-reverse unit 20, the second input terminal 2 of the common-mode inductor 501 is connected to the power supply ground, the first output terminal 3 of the common-mode inductor 501 is connected to the input terminal of the second anti-reverse unit 30, and the second output terminal 4 of the common-mode inductor 501 is grounded.
[0056] Alternatively, a 1000MHz / 700Ω common-mode inductor 501 can be used.
[0057] Optionally, a Y capacitor can be added to the back end of the common-mode inductor 501 to provide a low-impedance discharge path for the common-mode current. Common-mode noise flows to ground through the Y capacitor, thereby reducing the impact of common-mode interference on subsequent circuits.
[0058] In the above scheme, the common-mode suppression unit 50 is implemented by using a common-mode inductor 501, which can effectively suppress common-mode interference on power lines or signal lines, protect sensitive components in the circuit from common-mode noise, and provide a stable and reliable power supply for subsequent circuits.
[0059] In some embodiments, the pre-amplifier input protection circuit further includes an over / under voltage unit 60 for providing over / under voltage protection to the circuit.
[0060] The function of the over / under voltage unit 60 is to disconnect the power supply when the power input terminal of the circuit exceeds the safe voltage or falls below a certain voltage, so as to protect the downstream electronic components from damage under abnormal conditions.
[0061] Vehicle batteries currently commonly use one or two batteries connected in series. Their normal voltage is typically between 9-32V. In some special circumstances, such as the moment of starting the engine, the battery voltage drops to around 7V, or during surge voltage events, the battery voltage can even approach 60V. Therefore, as an implementation method, the undervoltage design of the overvoltage / undervoltage unit 60 is 6.5V, and the overvoltage design is 60V.
[0062] In the above scheme, the overvoltage and undervoltage unit 60 can prevent the circuit from being damaged due to excessively high or low voltage, thereby protecting the sensitive components in the circuit.
[0063] In some embodiments, refer to Figure 6 , Figure 6 This is a circuit connection diagram of an over / under voltage unit provided in an embodiment of this application.
[0064] The second anti-reverse unit 30 is connected to the DC-DC unit 40 via an over / under voltage unit 60. The over / under voltage unit 60 includes a third diode 601, a fourth diode 602, a fifth diode 603, a third resistor 604, a fourth resistor 605, a fifth resistor 606, a sixth resistor 607, a seventh resistor 608, an eighth resistor 609, a second power NMOS transistor 610, a third power NMOS transistor 611, a power PMOS transistor 612, a third capacitor 613, and a fourth capacitor 614. The gate of the second power NMOS transistor 610 is connected to one end of the third resistor 604 and one end of the fourth resistor 605. The other end of the third resistor 604 is connected to the anode of the third diode 601, and the other end of the fourth resistor 605 is grounded. The drain of the second power NMOS transistor 610 is connected to one end of the fifth resistor 606, one end of the sixth resistor 607, one end of the third capacitor 613, and one end of the third power NMOS transistor 611. The gate of the second power NMOS transistor 611 is connected to the anode of the fourth diode 602 at one end, the other end of the sixth resistor 607 and the other end of the third capacitor 613 are grounded, the cathodes of the third diode 601 and the fourth diode 602 are connected to the output terminal of the second anti-reverse unit 30, and the source of the second power NMOS transistor 610 is grounded; the drain of the third power NMOS transistor 611 is connected to one end of the seventh resistor 608, the other end of the seventh resistor 608 is connected to one end of the fourth capacitor 614, one end of the eighth resistor 609, the anode of the fifth diode 603 and the gate of the power PMOS transistor 612, the other end of the fourth capacitor 614, the other end of the eighth resistor 609, the cathode of the fifth diode 603 and the source of the power PMOS transistor 612 are connected to the output terminal of the second anti-reverse unit 30, and the source of the third power NMOS transistor 611 is grounded; the drain of the power PMOS transistor 612 is connected to the input terminal of the DC-DC unit 40.
[0065] The over / under voltage unit 60 adopts a power MOSFET structure. When the input voltage exceeds the voltage of the fourth diode 602, the third power NMOS transistor 611 is turned on through a certain voltage division between the fifth resistor 606 and the sixth resistor 607, which in turn turns on the power PMOS transistor 612, and the back-end circuit outputs voltage. When the input voltage exceeds 60V, the second power NMOS transistor 610 is turned on through the voltage of the third diode 601, the third resistor 604, and the fourth resistor 605, which turns off the third power NMOS transistor 611, which in turn turns off the power PMOS transistor 612, and the back-end circuit has no voltage output.
[0066] In the above scheme, the over- and under-voltage unit 60 is implemented using power NMOS transistors and power PMOS transistors 612, which can provide a stable and reliable power supply for the subsequent circuits.
[0067] In some embodiments, the third diode 601 and the fourth diode 602 include Zener diodes.
[0068] In the above scheme, the over- and under-voltage unit 60 is implemented using a Zener diode, which can achieve precise voltage clamping and provide reliable over- and under-voltage protection for the circuit.
[0069] It should be noted that this application does not limit the specific implementation of the DCDC unit 40, and those skilled in the art can make a reasonable selection based on the circuit conditions. In some embodiments, refer to Figure 7 , Figure 7 This is a circuit connection diagram of a DC-DC unit provided in an embodiment of this application. The voltage conversion chip can be model JWH5123S. If a surge voltage exists, its voltage will approach 60V after being clamped by the front-end transient voltage suppression unit 10. Therefore, to ensure that the device can still operate normally under these conditions, the operating voltage of the DC-DC unit 40 can be higher than 60V.
[0070] In some embodiments, refer to Figure 8 , Figure 8 This application provides a schematic diagram of another pre-amplifier input protection circuit.
[0071] This application also provides an aftermarket vehicle that includes the front-stage input protection circuit described in any of the foregoing embodiments.
[0072] In the embodiments provided in this application, it should be understood that the disclosed circuits can be implemented in other ways. The circuit embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.
[0073] Furthermore, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0074] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A pre-amplifier input protection circuit, characterized in that, Applied to aftermarket vehicles, it includes a front-end transient voltage suppression unit, a first anti-reverse voltage unit, a second anti-reverse voltage unit, and a DC-DC unit; The input terminal of the front-end transient voltage suppression unit is connected to an external power supply. The output terminal of the front-end transient voltage suppression unit is connected to the input terminal of the first anti-reverse unit. The output terminal of the first anti-reverse unit is connected to the input terminal of the second anti-reverse unit and is used to connect to the subsequent drive circuit. The output terminal of the second anti-reverse unit is connected to the input terminal of the DC-DC unit. The output terminal of the DC-DC unit is used to connect to the subsequent control circuit.
2. The circuit according to claim 1, characterized in that, The front-end transient voltage suppression unit includes a bidirectional TVS diode; One end of the bidirectional TVS diode is connected to the external power supply and the input terminal of the first anti-reverse unit, and the other end of the bidirectional TVS diode is connected to the isolation ground.
3. The circuit according to claim 1, characterized in that, The first anti-reverse unit includes a first power NMOS transistor, a first resistor, a second resistor, a first capacitor, and a first diode; The gate of the first power NMOS transistor is connected to one end of the first resistor, the other end of the first resistor is connected to the output of the front-end transient voltage suppression unit and the input of the second anti-reverse unit, the drain of the first power NMOS transistor is connected to the isolation ground, the source of the first power NMOS transistor is connected to the anode of the first diode, one end of the second resistor, one end of the first capacitor and the power supply ground, and the cathode of the first diode, the other end of the second resistor and the other end of the first capacitor are connected to the gate of the first power NMOS transistor.
4. The circuit according to claim 1, characterized in that, The second anti-reverse unit includes a second diode and a second capacitor; The anode of the second diode is connected to the output terminal of the first anti-reverse unit, the cathode of the second diode is connected to one end of the second capacitor and the input terminal of the DC-DC unit, and the other end of the second capacitor is grounded.
5. The circuit according to claim 1, characterized in that, Also includes: The common-mode rejection unit is used to suppress common-mode interference of the external power supply and then output it to the DC-DC unit.
6. The circuit according to claim 5, characterized in that, The first anti-reverse unit is connected to the second anti-reverse unit through the common-mode suppression unit, wherein the common-mode suppression unit includes a common-mode inductor; The first input terminal of the common-mode inductor is connected to the output terminal of the first anti-reverse unit, the second input terminal of the common-mode inductor is connected to the power ground, the first output terminal of the common-mode inductor is connected to the input terminal of the second anti-reverse unit, and the second output terminal of the common-mode inductor is grounded.
7. The circuit according to claim 1, characterized in that, Also includes: The over / under voltage unit is used to provide over / under voltage protection for the circuit.
8. The circuit according to claim 7, characterized in that, The second anti-reverse unit is connected to the DC-DC unit through the over / under voltage unit. The over / under voltage unit includes a third diode, a fourth diode, a fifth diode, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second power NMOS transistor, a third power NMOS transistor, a power PMOS transistor, a third capacitor, and a fourth capacitor. The gate of the second power NMOS transistor is connected to one end of the third resistor and one end of the fourth resistor. The other end of the third resistor is connected to the anode of the third diode. The other end of the fourth resistor is grounded. The drain of the second power NMOS transistor is connected to one end of the fifth resistor, one end of the sixth resistor, one end of the third capacitor, and the gate of the third power NMOS transistor. The other end of the fifth resistor is connected to the anode of the fourth diode. The other ends of the sixth resistor and the other end of the third capacitor are grounded. The cathodes of the third diode and the fourth diode are connected to the output terminal of the second anti-reverse unit. The source of the second power NMOS transistor is grounded. The drain of the third power NMOS transistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the fourth capacitor, one end of the eighth resistor, the anode of the fifth diode and the gate of the power PMOS transistor, the other end of the fourth capacitor, the other end of the eighth resistor, the cathode of the fifth diode and the source of the power PMOS transistor are connected to the output terminal of the second anti-reverse unit, and the source of the third power NMOS transistor is grounded. The drain of the power PMOS transistor is connected to the input terminal of the DC-DC unit.
9. The circuit according to claim 8, characterized in that, The third diode and the fourth diode include Zener diodes.
10. A retrofit vehicle, characterized in that, Includes the pre-amplifier input protection circuit as described in any one of claims 1-9.