Vehicle terminal power supply anti-interference circuit

Abstract

The application provides a kind of vehicle terminal power supply anti-interference circuit, including anti-reverse connection protection circuit, surge protection circuit, EMI filter circuit, power module circuit and output filter circuit.EMI filter circuit includes magnetic beads, four filter capacitors, common mode inductor, differential mode inductor and fifth filter capacitor.Power module circuit includes power stabilizing chip, freewheeling diode, first resistor, sixth filter capacitor, filter energy storage capacitor and energy storage inductor.Output filter circuit includes second TVS tube, second resistor and eighth filter capacitor.In the vehicle terminal power supply anti-interference circuit of the application, EMI filter circuit is designed for power stabilizing chip, and the output of power module is optimized at the same time, to ensure that EMC and EMI of vehicle power supply meet standard requirements, reduce electromagnetic interference on vehicle equipment and vehicle system, and ensure normal operation.

Description

[0001] This application is a divisional application of the invention patent application filed by the applicant on November 29, 2022, with application number 2022115140860 and application title "Vehicle Terminal Power Supply Anti-interference Circuit". Technical Field

[0002] This invention relates to the field of vehicle terminal power supply technology, and more specifically to an anti-interference circuit for vehicle terminal power supply. Background Technology

[0003] With the widespread use of in-vehicle electronic devices, such as GPS positioning modules, in-vehicle T-BOXs, cameras, and alarms, online vehicle monitoring, dispatch management, and OBD information uploading are now possible. In-vehicle terminals typically operate using the vehicle's battery power, connected to the vehicle's electrical output interfaces (cigarette lighter interface, 12VDC, 10VDC, or 5VDC, etc.). However, this power supply to the in-vehicle terminal can cause instability in the vehicle's infotainment system and other electronic systems, such as malfunctions in navigation modules, radio playback, and entertainment systems. This is because the in-vehicle terminal's power supply interferes with the vehicle's overall power system. Furthermore, in-vehicle electronic devices generate significant electromagnetic interference during operation. This interference has a wide frequency band and propagates into the vehicle's power system through conduction, coupling, or radiation, causing instability in the vehicle's infotainment system and modules. This is especially true in the field of electric vehicles (new energy vehicles), which have numerous electrical nodes, control devices, and power devices, inevitably generating significant electromagnetic interference during operation, creating a more complex and severe electromagnetic environment.

[0004] The national standard GB / T32960.2-2016, Technical Specification for Remote Service and Management System of Electric Vehicles, Part 2, sets forth the power supply requirements for on-board terminals. It employs voltage-based conducted emission (VCE) testing and specifies the electrical adaptability, environmental adaptability, and electromagnetic compatibility performance of the on-board terminals, including prescribed limits for conducted emissions. Currently, many on-board terminals are developed and sold by third-party manufacturers, and the power supply circuits used in these terminals often fail to meet automotive-grade immunity requirements in terms of electrical adaptability, environmental adaptability, and electromagnetic compatibility, thus affecting the operation of the vehicle's own systems when used in vehicles. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to propose a vehicle-mounted terminal power supply conducted emission anti-interference circuit with a simple circuit structure and high reliability, ensuring that the power supply circuit meets the standard requirements for both EMC and EMI.

[0006] According to a first aspect of the present invention, an anti-interference circuit for vehicle terminal power supply is provided, comprising a reverse connection protection circuit, a surge protection circuit, an EMI filter circuit, a power module circuit, and an output filter circuit connected in sequence.

[0007] The reverse connection protection circuit includes a first diode D1, which is connected between the VBAT power input terminal to prevent reverse connection of the power supply.

[0008] The surge protection circuit includes a first TVS diode D2 connected to the power input terminal;

[0009] The EMI filter circuit includes a ferrite bead L1, a first filter capacitor C1, a second filter capacitor C2, a third filter capacitor C3, a fourth filter capacitor C4, a common-mode inductor L2, a differential-mode inductor L3, and a fifth filter capacitor C5.

[0010] - The first filter capacitor C1, the second filter capacitor C2, the third filter capacitor C3, the fourth filter capacitor C4 and the common mode inductor L2 constitute a common mode inductor filter circuit. The first filter capacitor C1, the second filter capacitor C2, the third filter capacitor C3 and the fourth filter capacitor C4 are symmetrically arranged at both ends of the common mode inductor L2.

[0011] - One end of the magnetic bead L1 is connected to the power input terminal to suppress high-frequency noise and spike interference in the power line and absorb electrostatic pulses. The other end is connected to the input terminal of the common-mode inductor filter circuit, that is, connected to the positive terminal of the first filter capacitor C1.

[0012] - The output terminal of the common-mode inductor filter circuit is connected to the differential-mode inductor L3 and the fifth filter capacitor C5. The differential-mode inductor L3 and the fifth filter capacitor C5 constitute the first LC filter circuit.

[0013] The power module circuit includes a power regulator chip Q1, a freewheeling diode D3, a first resistor R1, a sixth filter capacitor C6, a filter energy storage capacitor C7, and an energy storage inductor L4.

[0014] The IN pin of the power regulator chip Q1 is connected to the differential mode inductor L3 and the fifth filter capacitor C5. Pins 5 and 3 of the power regulator chip Q1 are connected and grounded together, enabling the PWM regulation of the power regulator chip Q1. The output of pin 2 is connected to the first end of the energy storage inductor L4, and the second end of the energy storage inductor L4 is connected to the filter energy storage capacitor C7. The positive terminal of the freewheeling diode D3 is connected to ground, and the negative terminal is connected to pin 2 of the power regulator chip Q1. The first resistor R1 and the sixth filter capacitor C6 form the first RC filter circuit, one end of which is connected to pin 2 of the power regulator chip Q1, and the other end is grounded with pins 5 and 3 of the power regulator chip Q1.

[0015] The output filter circuit includes a second TVS diode D4, a second resistor R2, and an eighth filter capacitor C8. The second TVS diode D4 is connected to the chip power supply terminal VCC and pin 4 of the power supply regulator chip Q1 to prevent the chip power supply terminal VCC voltage from exceeding a preset value. The second resistor R2 and the eighth filter capacitor C8 are connected in parallel to form a second RC filter circuit.

[0016] The first RC filter circuit consists of a first resistor R1 and a sixth filter capacitor C6 connected in series. The resistance value of the first resistor R1 is in the range of 1-10kΩ, and the capacitance of the sixth filter capacitor C6 is in the range of 10pf-33pf.

[0017] In the second RC filter circuit, which is formed by the second resistor R2 and the eighth filter capacitor C8 connected in parallel, the resistance value of the second resistor R2 is ≥10KΩ and the capacitance value of the eighth filter capacitor C8 is ≥0.01uf.

[0018] In the embodiments of the present invention, the vehicle terminal power supply anti-interference circuit proposed in the present invention specifically refers to a power supply anti-interference circuit for a vehicle urea pump.

[0019] Combining the above technical solutions, the vehicle terminal power supply anti-interference circuit proposed in this invention designs an EMI filter circuit for the power supply regulator chip and optimizes the output of the power module to ensure that the vehicle power supply's EMC and EMI anti-electromagnetic interference performance meets the standard requirements. Moreover, for different input voltages, the parameters of the common-mode inductor, differential-mode inductor, and capacitor can be adjusted to reduce EMI electromagnetic interference, thereby reducing electromagnetic interference to vehicle equipment and vehicle systems and ensuring the normal operation of vehicle systems and vehicle electronic systems.

[0020] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below may be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other. Furthermore, all combinations of the claimed subject matter are considered part of the inventive subject matter of this disclosure.

[0021] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0022] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0023] Figure 1 This is a schematic diagram of the circuit principle of the vehicle terminal power supply anti-interference circuit according to an embodiment of the present invention. Detailed Implementation

[0024] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0025] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the invention disclosed may be used alone or in any suitable combination with other aspects of the invention disclosed.

[0026] Combination Figure 1 The vehicle terminal power supply anti-interference circuit of the exemplary embodiment shown is characterized in that it includes a reverse connection protection circuit, a surge protection circuit, an EMI filter circuit, a power module circuit, and an output filter circuit connected in sequence.

[0027] Combination Figure 1 As shown, the reverse connection protection circuit includes a first diode D1, which is connected between the VBAT power input terminal to prevent reverse connection of the power supply.

[0028] The surge protection circuit includes a first TVS diode D2 connected to the power input terminal.

[0029] The EMI filter circuit includes a ferrite bead L1, a first filter capacitor C1, a second filter capacitor C2, a third filter capacitor C3, a fourth filter capacitor C4, a common-mode inductor L2, a differential-mode inductor L3, and a fifth filter capacitor C5.

[0030] The first filter capacitor C1, the second filter capacitor C2, the third filter capacitor C3, the fourth filter capacitor C4, and the common-mode inductor L2 constitute a common-mode inductor filter circuit. The first filter capacitor C1, the second filter capacitor C2, the third filter capacitor C3, and the fourth filter capacitor C4 are symmetrically arranged across the two ends of the common-mode inductor L2.

[0031] One end of the ferrite bead L1 is connected to the power input terminal to suppress high-frequency noise and spike interference in the power line and absorb electrostatic pulses. The other end is connected to the input terminal of the common-mode inductor filter circuit, that is, to the positive terminal of the first filter capacitor C1.

[0032] The output of the common-mode inductor filter circuit is connected to the differential-mode inductor L3 and the fifth filter capacitor C5. The differential-mode inductor L3 and the fifth filter capacitor C5 constitute the first LC filter circuit.

[0033] Combination Figure 1 As shown, the power module circuit includes a power regulator chip Q1, a freewheeling diode D3, a first resistor R1, a sixth filter capacitor C6, a filter energy storage capacitor C7, and an energy storage inductor L4.

[0034] The IN pin of the power regulator chip Q1 is connected to the differential mode inductor L3 and the fifth filter capacitor C5. Pins 5 and 3 of the power regulator chip Q1 are connected and grounded together, enabling the PWM regulation of the power regulator chip Q1. The output of pin 2 is connected to the first end of the energy storage inductor L4, and the second end of the energy storage inductor L4 is connected to the filter energy storage capacitor C7. The positive terminal of the freewheeling diode D3 is connected to ground, and the negative terminal is connected to pin 2 of the power regulator chip Q1. The first resistor R1 and the sixth filter capacitor C6 form the first RC filter circuit, one end of which is connected to pin 2 of the power regulator chip Q1, and the other end is grounded with pins 5 and 3 of the power regulator chip Q1.

[0035] Combination Figure 1 The example shown includes a second TVS diode D4, a second resistor R2, and an eighth filter capacitor C8. The second TVS diode D4 is connected to the chip power supply terminal VCC and pin 4 of the power supply regulator chip Q1 to prevent the chip power supply terminal VCC voltage from exceeding a preset value. The second resistor R2 and the eighth filter capacitor C8 are connected in parallel to form a second RC filter circuit.

[0036] Combination Figure 1 As shown, in the wiring of one side of the common mode inductor L2, its positive terminal is connected to the positive terminal of the ferrite bead L1, the positive terminal of the first filter capacitor C1, and one end of the second filter capacitor C2, while its negative terminal is grounded together with the negative terminal of the first filter capacitor C1 and the other end of the second filter capacitor C2; the positive terminal of the first TVS diode D2 is connected in parallel to the negative terminal of the first filter capacitor C1 and grounded together with it, and the negative terminal of the first TVS diode D2 is connected to the power input terminal.

[0037] In the wiring on the other side of the common-mode inductor L2, its positive terminal is connected to one end of the third filter capacitor C3, the positive terminal of the fourth filter capacitor C4, and the first end of the differential-mode inductor L3. The second end of the differential-mode inductor L3 is connected to one end of the fifth filter capacitor C5 and connected to pin 1 of the power regulator chip Q1. Its negative terminal is connected to the other end of the third filter capacitor C3, the negative terminal of the fourth filter capacitor C4, and the other end of the fifth filter capacitor C5, and is connected to pins 5 and 3 of the power regulator chip Q1 and grounded together.

[0038] The first filter capacitor C1 and the fourth filter capacitor C4 are electrolytic capacitors with the same parameters. The third filter capacitor C3 and the second filter capacitor C2 are capacitors with the same parameters. The first filter capacitor C1 and the second filter capacitor C2 are connected in parallel on the same side of the common mode inductor L2, and the third filter capacitor C3 and the fourth filter capacitor C4 are connected in parallel.

[0039] In various embodiments of the present invention, the capacitance of the first filter capacitor C1 and the fourth filter capacitor C4 is >= 100uF; the capacitance of the third filter capacitor C3 and the second filter capacitor C2 is between 0.1uF and 2.2uF; the impedance of the common mode inductor L2 is > 230Ω; and the impedance of the ferrite bead is between 120-470Ω.

[0040] The differential-mode capacitance of differential-mode inductor L3 is >=10uH, and the capacitance of the fifth filter capacitor C5 is between 0.01uF and 10uF.

[0041] exist Figure 1 In the example shown, the power regulator chip Q1 is an LM2596S power regulator chip.

[0042] Combination Figure 1 As shown, the first RC filter circuit is composed of a first resistor R1 and a sixth filter capacitor C6 connected in series, wherein the resistance value of the first resistor R1 is in the range of 1-10kΩ, and the capacitance of the sixth filter capacitor C6 is in the range of 10pF-33pF.

[0043] In the second RC filter circuit, which is formed by the second resistor R2 and the eighth filter capacitor C8 connected in parallel, the resistance value of the second resistor R2 is ≥10KΩ and the capacitance value of the eighth filter capacitor C8 is ≥0.01uf.

[0044] The second LC filter circuit is composed of energy storage inductor L4 and filter energy storage capacitor C7, wherein the inductance value of energy storage inductor L4 is 33uH-100uH and the capacitance value of filter energy storage capacitor C7 is 22uf-100uf.

[0045] The parameters of the freewheeling diode D3 are set to ≥3A / 40V.

[0046] Table 1 illustrates, for example, the parameter selection ranges for each device in embodiments of the present invention and typical values ​​in exemplary embodiments of the present invention.

[0047] Table 1 - Parameter Selection Range and Typical Values

[0048] Devices scope Typical value L1 120-470Ω 470Ω L2 >230Ω 420Ω C1,C4 >=100uf 220uf C2,C3 0.1uf-2.2uf 0.1uf L3 >=10uh 10uh L4 33uh-100uh 33uh D1 >3A 5A D3 >=3A / 40V 3A / 40V C5 0.01uf-10uf 10 uf R1 10-10k 10Ω C6 10p-33p 33p D4 Vr=5V Vr=5V C7 22uf-100uf 100uf C8 >0.01uf 0.01uf R2 >=10K 10K

[0049] Combination Figure 1In the illustrated embodiment, the power supply reverse connection protection circuit composed of the first diode D1 aims to utilize the unidirectional conductivity of the first diode D1. When the power supply is reversed, the diode does not conduct in the reverse direction, thus preventing damage to the power supply circuit. In optional embodiments, the first diode D1 can be selected as a PRV or IR diode.

[0050] The surge protection circuit, composed of the first TVS diode D2, is connected to the power input terminal. Under specified reverse application conditions, the first TVS diode presents a high impedance state to the protected line. When the instantaneous voltage exceeds its breakdown voltage (rated reverse working voltage VWM), the TVS diode provides a low impedance path and diverts the instantaneous current flowing to the protected component to the TVS diode through a large current flow, while limiting the voltage across the protected component to the TVS clamping voltage (Vc). When the overvoltage condition disappears, the first TVS diode returns to the high impedance state. In optional embodiments, the rated reverse working voltage VWM of the selected TVS varies depending on the voltage level, but VWM should be slightly greater than the normal operating voltage of the protected power supply circuit.

[0051] like Figure 1 As shown, the ferrite bead L1 is connected to the power input terminal in the power supply input section, suppressing high-frequency noise and spike interference from the power line and absorbing electrostatic pulses. Simultaneously, the other end of the ferrite bead L1 is connected to the input terminal of the common-mode inductor filter circuit, i.e., the first filter capacitor C1.

[0052] Combination Figure 1 As shown, the four filter capacitors C1, C2, C3, and C4 are connected symmetrically on both sides of the common-mode inductor L2, and the two filter capacitors on the same side are connected in parallel. Specifically, they are placed in a symmetrical pattern when laying out the PCB.

[0053] In this embodiment of the invention, the common-mode inductor acts as a bidirectional filter: on the one hand, it filters out common-mode electromagnetic interference on the signal line; on the other hand, it suppresses its own electromagnetic interference to avoid affecting the normal operation of other electronic devices in the same electromagnetic environment. The common-mode inductor circuit is connected to the differential-mode inductors L3 and C5, and L3 and C5 form an LC circuit to achieve filtering and compensation. The principle of the LC filter circuit is actually a combination of the basic characteristics of L and C components. Because the capacitive reactance of capacitor xc=2nfc decreases with the increase of signal frequency, while the inductance of inductor xl=2f increases with the increase of signal frequency, if capacitors and inductors are connected in series, parallel, or mixed together, their combined impedance will also vary greatly with different signal frequencies. Therefore, different filter circuits will present different reactances to a certain frequency signal, thus allowing or blocking that frequency signal. Thus, the filter circuit plays the role of selecting and filtering out a certain frequency signal.

[0054] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. An anti-interference circuit for vehicle-mounted terminal power supply, characterized in that, It includes a reverse connection protection circuit, a surge protection circuit, an EMI filter circuit, a power module circuit, and an output filter circuit connected in sequence. The reverse connection protection circuit includes a first diode (D1) connected between the VBAT power input terminal to prevent reverse connection of the power supply; The surge protection circuit includes a first TVS diode (D2) connected to the power input terminal. The EMI filter circuit includes a ferrite bead (L1), a first filter capacitor (C1), a second filter capacitor (C2), a third filter capacitor (C3), a fourth filter capacitor (C4), a common-mode inductor (L2), a differential-mode inductor (L3), and a fifth filter capacitor (C5). - The first filter capacitor (C1), the second filter capacitor (C2), the third filter capacitor (C3), the fourth filter capacitor (C4), and the common mode inductor (L2) constitute a common mode inductor filter circuit. The first filter capacitor (C1), the second filter capacitor (C2), the third filter capacitor (C3), and the fourth filter capacitor (C4) are symmetrically arranged at both ends of the common mode inductor (L2). - One end of the magnetic bead (L1) is connected to the power input terminal to suppress high-frequency noise and spike interference in the power line and absorb electrostatic pulses. The other end is connected to the input terminal of the common-mode inductor filter circuit, that is, connected to the positive terminal of the first filter capacitor (C1). - The output terminal of the common-mode inductor filter circuit is connected to the differential-mode inductor (L3) and the fifth filter capacitor (C5). The differential-mode inductor (L3) and the fifth filter capacitor (C5) constitute the first LC filter circuit. The power module circuit includes a power regulator chip (Q1), a freewheeling diode (D3), a first resistor (R1), a sixth filter capacitor (C6), a filter energy storage capacitor (C7), and an energy storage inductor (L4). The IN pin of the power regulator chip (Q1) is connected to the differential mode inductor (L3) and the fifth filter capacitor (C5). Pins 5 and 3 of the power regulator chip (Q1) are connected and grounded together, enabling the PWM regulation of the power regulator chip (Q1). The output of pin 2 is connected to the first end of the energy storage inductor (L4), and the second end of the energy storage inductor (L4) is connected to the filter energy storage capacitor (C7). The positive terminal of the freewheeling diode (D3) is connected to ground, and the negative terminal is connected to pin 2 of the power regulator chip (Q1). The first resistor (R1) and the sixth filter capacitor (C6) form the first RC filter circuit, one end of which is connected to pin 2 of the power regulator chip (Q1), and the other end is grounded with pins 5 and 3 of the power regulator chip (Q1). The output filter circuit includes a second TVS diode (D4), a second resistor (R2), and an eighth filter capacitor (C8). The second TVS diode (D4) is connected to the chip power supply terminal VCC and pin 4 of the power supply regulator chip (Q1) to prevent the chip power supply terminal VCC voltage from exceeding a preset value. The second resistor (R2) and the eighth filter capacitor (C8) are connected in parallel to form a second RC filter circuit. The first RC filter circuit, which is composed of a first resistor (R1) and a sixth filter capacitor (C6) connected in series, has a resistance value of 1-10kΩ and a capacitance of 10pf-33pf. In the second RC filter circuit, which is formed by the second resistor (R2) and the eighth filter capacitor (C8) connected in parallel, the resistance value of the second resistor (R2) is ≥10KΩ and the capacitance value of the eighth filter capacitor (C8) is ≥0.01uf.

2. The vehicle-mounted terminal power supply anti-interference circuit according to claim 1, characterized in that, In the wiring of one side of the common mode inductor (L2), its positive terminal is connected to the positive terminal of the ferrite bead (L1), the positive terminal of the first filter capacitor (C1), and one end of the second filter capacitor (C2), while its negative terminal is grounded together with the negative terminal of the first filter capacitor (C1) and the other end of the second filter capacitor (C2); the positive terminal of the first TVS diode (D2) is connected in parallel to the negative terminal of the first filter capacitor (C1) and grounded together with it, while the negative terminal of the first TVS diode (D2) is connected to the power input terminal; In the wiring on the other side of the common-mode inductor (L2), its positive terminal is connected to one end of the third filter capacitor (C3), the positive terminal of the fourth filter capacitor (C4), and the first end of the differential-mode inductor (L3). The second end of the differential-mode inductor (L3) is connected to one end of the fifth filter capacitor (C5) and connected to pin 1 of the power regulator chip (Q1). Its negative terminal is connected to the other end of the third filter capacitor (C3), the negative terminal of the fourth filter capacitor (C4), and the other end of the fifth filter capacitor (C5), and is connected to pins 5 and 3 of the power regulator chip (Q1) and grounded together.

3. The vehicle-mounted terminal power supply anti-interference circuit according to claim 2, characterized in that, The first filter capacitor (C1) and the fourth filter capacitor (C4) are electrolytic capacitors with the same parameters. The third filter capacitor (C3) and the second filter capacitor (C2) are capacitors with the same parameters. The first filter capacitor (C1) and the second filter capacitor (C2) located on the same side of the common mode inductor (L2) are connected in parallel. The third filter capacitor (C3) and the fourth filter capacitor (C4) are connected in parallel.

4. The vehicle-mounted terminal power supply anti-interference circuit according to claim 3, characterized in that, The capacitance of the first filter capacitor (C1) and the fourth filter capacitor (C4) is >= 100uF; the capacitance of the third filter capacitor (C3) and the second filter capacitor (C2) is between 0.1uF and 2.2uF.

5. The vehicle-mounted terminal power supply anti-interference circuit according to claim 3, characterized in that, The impedance of the common-mode inductor (L2) is >230Ω, and the impedance of the ferrite bead is between 120-470Ω.

6. The vehicle-mounted terminal power supply anti-interference circuit according to claim 3, characterized in that, The differential mode capacitance of the differential mode inductor (L3) is >=10uH, and the capacitance of the fifth filter capacitor (C5) is between 0.01uf and 10uf.

7. The vehicle-mounted terminal power supply anti-interference circuit according to claim 2, characterized in that, The power regulator chip (Q1) is an LM2596S power regulator chip.

8. The vehicle-mounted terminal power supply anti-interference circuit according to claim 1, characterized in that, The rated reverse operating voltage VWM of the first TVS transistor (D2) is greater than the output operating voltage of the power module circuit.

9. The vehicle-mounted terminal power supply anti-interference circuit according to claim 1, characterized in that, The energy storage inductor (L4) and the filter energy storage capacitor (C7) constitute a second LC filter circuit, wherein the inductance value of the energy storage inductor (L4) is 33uH-100uH, and the capacitance value of the filter energy storage capacitor (C7) is 22uf-100uf.

10. The vehicle-mounted terminal power supply anti-interference circuit according to claim 1, characterized in that, The parameters of the freewheeling diode (D3) are set to ≥3A / 40V.

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