Multi-stage protection low-ripple power supply circuit for vehicle-mounted screen

Abstract

This application relates to a multi-stage protection low-ripple power supply circuit for vehicle-mounted screens. The multi-stage protection low-ripple power supply circuit for vehicle-mounted screens includes: an input module and a step-down output module. The input module includes a surge protection unit, a primary filter unit, a discharge unit, a secondary filter unit, and a tertiary filter unit. The surge protection unit is electrically connected to the primary filter unit, the discharge unit is electrically connected to the primary filter unit, the secondary filter unit is electrically connected to the discharge unit, and the tertiary filter unit is electrically connected to the secondary filter unit. The step-down output module is electrically connected to the tertiary filter unit. The solution provided by this application can effectively filter out electromagnetic interference of different frequency bands in the vehicle environment during the power input stage, thereby ensuring normal screen display.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to a multi-level protection low-ripple power supply circuit for automotive screens. Background Technology

[0002] In related technologies, current automotive screen power supply solutions only use a small number of capacitive capacitors for input filtering, failing to form a full-band filtering combination. This makes it impossible to effectively filter out electromagnetic interference of different frequency bands in the automotive environment, thus causing screen flickering and image distortion. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-level protection low-ripple power supply circuit for vehicle screens, which can effectively filter out electromagnetic interference of different frequency bands in the vehicle environment during the power input stage, thereby ensuring normal screen display.

[0004] The objective of this invention is achieved through the following technical solution: The first aspect of this application provides a multi-level protection low-ripple power supply circuit for an in-vehicle screen, comprising: an input module including a surge protection unit, a primary filter unit, a discharge unit, a secondary filter unit, and a tertiary filter unit, wherein the surge protection unit is electrically connected to the primary filter unit, the discharge unit is electrically connected to the primary filter unit, the secondary filter unit is electrically connected to the discharge unit, and the tertiary filter unit is electrically connected to the secondary filter unit; and a step-down output module electrically connected to the tertiary filter unit.

[0005] The surge protection unit includes a resistor R1 and a TVS diode D1. The resistor R1 is electrically connected to the first terminal of the TVS diode D1, and the second terminal of the TVS diode D1 is grounded.

[0006] The primary filter unit includes capacitors C1, C2, C3, C4, and C5. The first terminal of capacitor C1 is electrically connected to the first terminal of TVS diode D1, and the second terminal of capacitor C1 is grounded. The first terminal of capacitor C2 is electrically connected to the first terminal of capacitor C1, and the second terminal of capacitor C2 is grounded. The first terminal of capacitor C3 is electrically connected to the first terminal of capacitor C2, and the second terminal of capacitor C3 is grounded. The first terminal of capacitor C4 is electrically connected to the first terminal of capacitor C3, and the second terminal of capacitor C4 is grounded. The first terminal of capacitor C5 is electrically connected to the first terminal of capacitor C4, and the second terminal of capacitor C5 is grounded.

[0007] The discharge unit includes a resistor R2, the first end of which is electrically connected to the first end of the capacitor C5, and the second end of the resistor R2 is grounded.

[0008] The secondary filter unit includes capacitor C6 and capacitor C7. The first end of capacitor C6 is electrically connected to the first end of resistor R2, and the second end of capacitor C6 is grounded. The first end of capacitor C7 is electrically connected to the first end of capacitor C6, and the second end of capacitor C7 is grounded.

[0009] The three-stage filter unit includes an inductor L1, a capacitor C8, a capacitor C9, and a capacitor C10. The first end of the inductor L1 is electrically connected to the first end of the capacitor C7. The second end of the inductor L1 is electrically connected to the first ends of the capacitors C8, C9, and C10, respectively. The second ends of the capacitors C8, C9, and C10 are all grounded.

[0010] The step-down output module chip U1, capacitor C12, and capacitor C11 are described. The first end of capacitor C12 is electrically connected to the first end of capacitor C10, and the second end of capacitor C12 is grounded. The first end of capacitor C11 is electrically connected to the first end of capacitor C12, and the second end of capacitor C11 is grounded.

[0011] The step-down output module also includes resistors R3 and R4. The first end of resistor R3 is electrically connected to the first end of capacitor C11, the second end of resistor R3 is electrically connected to the first end of resistor R4 and chip U1, and the second end of resistor R4 is grounded.

[0012] The step-down output module also includes an inductor L2, a capacitor C16, a capacitor C14, and a capacitor C13. The first end of the inductor L2 is electrically connected to the first end of the capacitor C16, and the second end of the capacitor C16 is grounded. The second end of the inductor L2 is electrically connected to the chip U1. The first end of the capacitor C14 is electrically connected to the chip U1, and the second end of the capacitor C14 is grounded. The first end of the capacitor C13 is electrically connected to the chip U1, and the second end of the capacitor C13 is grounded.

[0013] The step-down output module also includes resistors R8, R10 and R7. The first end of resistor R8 is electrically connected to chip U1, the second end of resistor R8 is electrically connected to the first end of resistor R10, the first end of resistor R7 is electrically connected to chip U1, and the second end of resistor R10 is electrically connected to the second end of resistor R7.

[0014] Compared with the prior art, the present invention has at least the following advantages: This application achieves the filtering of electromagnetic interference in different frequency bands in the vehicle environment during the power input stage by setting up a primary filtering unit, a secondary filtering unit, and a tertiary filtering unit, thereby ensuring normal screen display. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.

[0016] Figure 1 This is a functional block diagram of a multi-level protection low-ripple power supply circuit for a vehicle screen according to an embodiment of the present invention. Figure 2 This is a circuit diagram of the input module in one embodiment of the present invention; Figure 3 This is a circuit diagram of a step-down output module according to an embodiment of the present invention.

[0017] Figure 4 This is a circuit diagram of another embodiment of the buck output module in one embodiment of the present invention. Detailed Implementation

[0018] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0019] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0020] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings.

[0022] See Figure 1A multi-level protection low-ripple power supply circuit for a vehicle-mounted screen includes: an input module 100 and a step-down output module 200. The input module 100 includes a surge protection unit, a primary filter unit, a discharge unit, a secondary filter unit, and a tertiary filter unit. The surge protection unit is electrically connected to the primary filter unit, the discharge unit is electrically connected to the primary filter unit, the secondary filter unit is electrically connected to the discharge unit, and the tertiary filter unit is electrically connected to the secondary filter unit. The step-down output module 200 is electrically connected to the tertiary filter unit.

[0023] It should be noted that by setting up a primary filtering unit, a secondary filtering unit, and a tertiary filtering unit, electromagnetic interference of different frequency bands in the vehicle environment can be filtered out during the power input stage, thereby ensuring normal screen display.

[0024] See Figure 2 In one embodiment, the surge protection unit includes a resistor R1 and a TVS diode D1. The resistor R1 is electrically connected to the first terminal of the TVS diode D1, and the second terminal of the TVS diode D1 is grounded.

[0025] It should be noted that resistor R1 is a 1Ω damping resistor, which is connected in series between the 12V input and the TVS diode D1. The diode is an automotive-grade bidirectional TVS with a clamping voltage of less than 28V and a maximum discharge current of more than 1A. The damping resistor is used to reduce surge clamping overshoot and prevent transient high voltage from damaging downstream devices.

[0026] See Figure 2 In one embodiment, the primary filter unit includes capacitors C1, C2, C3, C4, and C5. The first terminal of capacitor C1 is electrically connected to the first terminal of TVS diode D1, and the second terminal of capacitor C1 is grounded. The first terminal of capacitor C2 is electrically connected to the first terminal of capacitor C1, and the second terminal of capacitor C2 is grounded. The first terminal of capacitor C3 is electrically connected to the first terminal of capacitor C2, and the second terminal of capacitor C3 is grounded. The first terminal of capacitor C4 is electrically connected to the first terminal of capacitor C3, and the second terminal of capacitor C4 is grounded. The first terminal of capacitor C5 is electrically connected to the first terminal of capacitor C4, and the second terminal of capacitor C5 is grounded.

[0027] It should be noted that the first-stage filter unit uses a full-band capacitor combination, with a 10uF electrolytic capacitor C1, a 22pF ceramic capacitor C2, a 2.2nF ceramic capacitor C3, a 22nF ceramic capacitor C4, and a 100nF ceramic capacitor C5 connected in parallel to ground. The 10uF electrolytic capacitor is used to filter out low-frequency ripple in the input power supply and to store energy. The 22pF to 100nF capacitors cover the high-frequency band of 1MHz to 1GHz and are used to suppress high-frequency conducted interference in the vehicle environment.

[0028] See Figure 2In one embodiment, the discharge unit includes a resistor R2, the first end of which is electrically connected to the first end of the capacitor C5, and the second end of the resistor R2 is grounded.

[0029] It should be noted that the discharge unit uses a 15kΩ resistor R2, one end of which is connected to the output of the first-stage filter unit, and the other end is grounded. This is used to quickly discharge the residual charge in the filter capacitor after power failure, so as to prevent the capacitor from charging the chip U1 when power is restored.

[0030] See Figure 2 In one embodiment, the secondary filter unit includes capacitor C6 and capacitor C7. The first end of capacitor C6 is electrically connected to the first end of resistor R2, and the second end of capacitor C6 is grounded. The first end of capacitor C7 is electrically connected to the first end of capacitor C6, and the second end of capacitor C7 is grounded.

[0031] It should be noted that the secondary filter unit uses a 10uF electrolytic capacitor C6 and a 100nF capacitor C7 connected in parallel to ground, between the output of the discharge unit and the tertiary filter unit, to further filter out mid-to-high frequency noise, stabilize the input voltage, and provide a buffer for the subsequent tertiary filter unit.

[0032] See Figure 2 In one embodiment, the three-stage filter unit includes an inductor L1, a capacitor C8, a capacitor C9, and a capacitor C10. The first end of the inductor L1 is electrically connected to the first end of the capacitor C7. The second end of the inductor L1 is electrically connected to the first ends of the capacitors C8, C9, and C10, respectively. The second ends of the capacitors C8, C9, and C10 are all grounded.

[0033] It should be noted that the third-stage filtering unit is a π-type LC filtering unit, which consists of a 15uH inductor L1, a 10nF capacitor C8, a 10uF electrolytic capacitor C9, and a 100nF capacitor C10. This module is connected between the input protection filtering module and the VIN terminal of the buck module. The 15uH inductor L1 is connected in series at the output of the second-stage input filtering unit, and then connected to ground in parallel through the 10nF, 10uF, and 100nF capacitors before outputting VIN to the buck output module. Its core function is to suppress the backflow of switching noise from chip U1 to the input side, and at the same time further filter out residual high-frequency noise to ensure the stability of the voltage input to chip U1.

[0034] See Figure 3In one embodiment, the step-down output module 200 includes a chip U1, capacitors C12 and C11. The first terminal of capacitor C12 is electrically connected to the first terminal of capacitor C10, and the second terminal of capacitor C12 is grounded. The first terminal of capacitor C11 is electrically connected to the first terminal of capacitor C12, and the second terminal of capacitor C11 is grounded. The step-down output module 200 also includes resistors R3 and R4. The first terminal of resistor R3 is electrically connected to the first terminal of capacitor C11, and the second terminal of resistor R3 is electrically connected to both the first terminal of resistor R4 and chip U1. The second terminal of resistor R4 is grounded.

[0035] It should be noted that the chip U1 model can be MPQ4372GVE. The PG pin has an open-drain output structure and is pulled up to the internal VCC pin power supply through a 10KΩ resistor R6. When the output voltage is within the normal range, PG outputs a high level to indicate the power supply operating status. Pulling it up to VCC ensures that the signal is valid when the chip U1 operates independently, unaffected by the external system power supply. The SYNCIN / MODE pin is the chip's operating mode configuration pin. Pulled up to the internal VCC of the chip U1 through a resistor, it configures the chip U1 to automatic CCM operating mode. Under no load and full load, it maintains a fixed frequency, and under light load, it maintains a constant frequency and low output ripple. This design balances efficiency and output stability, adapting to dynamic load changes in automotive displays. The output of the three-stage filter unit is connected to VIN, followed by a 1uF capacitor C12 and a 100nF capacitor C11 connected in parallel to ground. These capacitors are connected to the VIN pin of the chip. They provide high-frequency decoupling and transient current support for the chip U1, filtering out high-frequency noise from the input and reverse switching noise. They are also connected to the EN pin through a resistor R3, and then to a pull-down resistor R4. This can suppress power-on glitches and prevent the EN pin from being falsely triggered. At the same time, they absorb input surge voltages, improving the chip U1's immunity and operational reliability.

[0036] See Figure 3 In one embodiment, the step-down output module 200 further includes an inductor L2, capacitors C16, C14, and C13. The first terminal of inductor L2 is electrically connected to the first terminal of capacitor C16, and the second terminal of capacitor C16 is grounded. The second terminal of inductor L2 is electrically connected to chip U1. The first terminal of capacitor C14 is electrically connected to chip U1, and the second terminal of capacitor C14 is grounded. The first terminal of capacitor C13 is electrically connected to chip U1, and the second terminal of capacitor C13 is grounded. Specifically, the step-down output module 200 also includes resistors R8, R10, and R7. The first terminal of resistor R8 is electrically connected to chip U1, and the second terminal of resistor R8 is electrically connected to the first terminal of resistor R10. The first terminal of resistor R7 is electrically connected to chip U1, and the second terminal of resistor R10 is electrically connected to the second terminal of resistor R7.

[0037] It should be noted that the SW pin is used to output the stepped-down voltage, employing a combination of an LC circuit with a 22uH inductor L2 and a 47uF electrolytic capacitor C16 to convert the switching square wave into a smooth and stable DC voltage to VOUT. A 100nF capacitor C15 is connected in series between the BST and SW pins to provide the gate drive voltage for the high-side MOSFET inside chip U1. The ICS pin is directly connected to the VCC power supply of chip U1, enabling the default operation of chip U1's built-in fixed soft-start time and current limiting protection parameters. The VBIAS pin is grounded through a 1uF capacitor C14 to achieve bias power supply filtering and regulation, ensuring stable operation of the chip's control loop. The VCC pin is the output of chip U1's internal 5V linear regulator, supplying power to the internal drive and control circuits, and is grounded through a 1uF capacitor C13 for filtering and regulation.

[0038] The VOUT / FB pins are externally connected to a 123kΩ voltage divider resistor R8 and a 10kΩ voltage divider resistor R10. The 123kΩ resistor acts as a pull-up resistor, connected to VOUT after the SW pin, while the 10kΩ resistor acts as a pull-down resistor. The internal reference voltage of chip U1 is 0.6V, and the voltage divider ratio ensures a precise 8V output. The FREQ pin is the chip's switching frequency setting pin, pulled down to ground by resistor R7. It is used to set a fixed switching frequency, ensuring the stability of chip U1's operating frequency and preventing frequency drift that could increase output ripple or interfere with the display.

[0039] See Figure 4 In another embodiment, the step-down output module 200 further includes capacitors C17, C18, C19, and C20. The first terminals of capacitors C17, C18, C19, and C20 are electrically connected to the second terminal of resistor R8, and the second terminals of capacitors C17, C18, C19, and C20 are grounded.

[0040] It should be noted that capacitors C17, C18, C19, and C20 are used to filter out residual high-frequency switching noise from the buck module, further reducing output ripple and providing a cleaner DC voltage for subsequent circuits. This is a high-frequency spike suppression and light-load stabilization unit.

[0041] See Figure 4In another embodiment, the step-down output module 200 further includes a ferrite bead B1, resistors R11, R12, R13, and R14. The first end of the ferrite bead B1 is electrically connected to the first end of the capacitor C20 and the first end of the resistor R11. The second end of the ferrite bead B1 is electrically connected to the second end of the resistor R11. The first end of the resistor R12 is electrically connected to the first end of the resistor R11, and the second end of the resistor R12 is electrically connected to the second end of the resistor R11. The first end of the resistor R13 is electrically connected to the first end of the resistor R12, and the second end of the resistor R13 is electrically connected to the second end of the resistor R12. The first end of the resistor R14 is electrically connected to the first end of the resistor R13, and the second end of the resistor R14 is electrically connected to the second end of the resistor R13. It should be noted that the ferrite bead B1 is used to filter out high-frequency spikes above 100MHz to prevent noise interference with the screen's T-Con board and backlight circuit. Four 4.7kΩ resistors R11-R14 are connected in parallel, with an equivalent resistance of 1.175kΩ, serving as a dummy load to stabilize light-load operation, preventing frequency hopping in the DC-DC chip and improving output stability under all operating conditions.

[0042] See Figure 4 In another embodiment, the step-down output module 200 further includes a resistor R15, a TVS diode D2, a capacitor C21, a capacitor C22, and a capacitor C23. The first end of the resistor R15 is electrically connected to the second end of the ferrite bead B1, and the second end of the resistor R15 is electrically connected to the first end of the TVS diode D2, the first end of the capacitor C21, the first end of the capacitor C22, and the first end of the capacitor C23, respectively. The second ends of the TVS diode D2, the second ends of the capacitor C21, the second ends of the capacitor C22, and the second ends of the capacitor C23 are grounded.

[0043] It should be noted that a 0.5Ω damping resistor R15 is connected in series before the TVS diode D2, with a diode clamping voltage ≤8V, to protect against output overvoltage and ESD interference. The 0.5Ω damping resistor buffers overvoltage current to prevent transient current generated when the TVS diode D2 is turned on from damaging the screen load. Subsequently, a 10uF electrolytic capacitor C21, a 1uF capacitor C22, and a 100nF capacitor C23 are connected in parallel to ground to further stabilize the output voltage, filter out residual mid-to-high frequency noise, and ensure the purity of the voltage input to the vehicle screen.

[0044] The solution of this application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have different focuses; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. Those skilled in the art should also understand that the actions and modules involved in the specification are not necessarily essential to this application. Furthermore, it is understood that the steps in the method of this application embodiment can be adjusted, combined, and deleted according to actual needs, and the modules in the device of this application embodiment can be combined, divided, and deleted according to actual needs.

[0045] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A multi-level protection low-ripple power supply circuit for a vehicle-mounted screen, characterized in that, include: The input module includes a surge protection unit, a primary filter unit, a discharge unit, a secondary filter unit, and a tertiary filter unit. The surge protection unit is electrically connected to the primary filter unit, the discharge unit is electrically connected to the primary filter unit, the secondary filter unit is electrically connected to the discharge unit, and the tertiary filter unit is electrically connected to the secondary filter unit. The step-down output module is electrically connected to the three-stage filter unit.

2. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 1, characterized in that, The surge protection unit includes a resistor R1 and a TVS diode D1. The resistor R1 is electrically connected to the first terminal of the TVS diode D1, and the second terminal of the TVS diode D1 is grounded.

3. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 2, characterized in that, The primary filter unit includes capacitors C1, C2, C3, C4, and C5. The first terminal of capacitor C1 is electrically connected to the first terminal of TVS diode D1, and the second terminal of capacitor C1 is grounded. The first terminal of capacitor C2 is electrically connected to the first terminal of capacitor C1, and the second terminal of capacitor C2 is grounded. The first terminal of capacitor C3 is electrically connected to the first terminal of capacitor C2, and the second terminal of capacitor C3 is grounded. The first terminal of capacitor C4 is electrically connected to the first terminal of capacitor C3, and the second terminal of capacitor C4 is grounded. The first terminal of capacitor C5 is electrically connected to the first terminal of capacitor C4, and the second terminal of capacitor C5 is grounded.

4. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 3, characterized in that, The discharge unit includes a resistor R2, the first end of which is electrically connected to the first end of the capacitor C5, and the second end of the resistor R2 is grounded.

5. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 4, characterized in that, The secondary filter unit includes capacitor C6 and capacitor C7. The first end of capacitor C6 is electrically connected to the first end of resistor R2, and the second end of capacitor C6 is grounded. The first end of capacitor C7 is electrically connected to the first end of capacitor C6, and the second end of capacitor C7 is grounded.

6. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 5, characterized in that, The three-stage filter unit includes an inductor L1, a capacitor C8, a capacitor C9, and a capacitor C10. The first end of the inductor L1 is electrically connected to the first end of the capacitor C7. The second end of the inductor L1 is electrically connected to the first ends of the capacitors C8, C9, and C10, respectively. The second ends of the capacitors C8, C9, and C10 are all grounded.

7. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 6, characterized in that, The step-down output module chip U1, capacitor C12, and capacitor C11 are described. The first end of capacitor C12 is electrically connected to the first end of capacitor C10, and the second end of capacitor C12 is grounded. The first end of capacitor C11 is electrically connected to the first end of capacitor C12, and the second end of capacitor C11 is grounded.

8. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 7, characterized in that, The step-down output module also includes resistors R3 and R4. The first end of resistor R3 is electrically connected to the first end of capacitor C11, the second end of resistor R3 is electrically connected to the first end of resistor R4 and chip U1, and the second end of resistor R4 is grounded.

9. The multi-level protection low-ripple power supply circuit for vehicle screens according to claim 7, characterized in that, The step-down output module also includes an inductor L2, a capacitor C16, a capacitor C14, and a capacitor C13. The first end of the inductor L2 is electrically connected to the first end of the capacitor C16, and the second end of the capacitor C16 is grounded. The second end of the inductor L2 is electrically connected to the chip U1. The first end of the capacitor C14 is electrically connected to the chip U1, and the second end of the capacitor C14 is grounded. The first end of the capacitor C13 is electrically connected to the chip U1, and the second end of the capacitor C13 is grounded.

10. The multi-level protection low-ripple power supply circuit for vehicle-mounted screens according to claim 7, characterized in that, The step-down output module also includes resistors R8, R10 and R7. The first end of resistor R8 is electrically connected to chip U1, the second end of resistor R8 is electrically connected to the first end of resistor R10, the first end of resistor R7 is electrically connected to chip U1, and the second end of resistor R10 is electrically connected to the second end of resistor R7.

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