An automobile vehicle lamp board-level high-integration constant-current boost converter circuit

Abstract

The utility model provides a kind of automobile car light board level high integration constant current boost converter circuit, comprising: boost topology module and control chip, boost topology module includes inductance, switch tube, diode and output capacitor, inductance, switch tube, diode and output capacitor are sequentially connected, form boost energy conversion loop;Control chip is as the control chip of boost energy conversion loop;Wherein, switch tube includes core switch tube, the input end of inductance is connected direct current power supply, the output end of inductance is connected the drain of core switch tube and the anode of diode respectively, the cathode of diode is connected output capacitor, the output end of output capacitor is connected car light emitting diode load;Control chip includes gate drive pin, gate drive pin is connected with the gate of core switch tube.The utility model solves the problem that a large amount of manpower and time cost is increased due to the need for repeated debugging and verification when handling electromagnetic compatibility and other experiments in the prior art due to the design of the driving circuit.

Description

Technical Field

[0001] This utility model relates to the field of automotive lighting technology, and more specifically, to a high-integration constant current boost converter circuit at the automotive lighting board level. Background Technology

[0002] With the development of the automotive industry, car headlight designs are becoming increasingly diverse and personalized, resulting in increasingly limited and irregular installation space for LED driver circuit boards. Therefore, higher demands are placed on the integration and miniaturization of LED drivers, making DC-DC-BOOST type driver circuits the mainstream technology choice due to their high efficiency and high power density. However, existing DC-DC-BOOST type LED driver circuits, designed for specific automotive headlight projects, have at least one inherent drawback: each new car model or headlight design requires a redesign of the driver board circuit and layout to adapt to different space and optical requirements. When dealing with electromagnetic compatibility (EMC) and other experimental issues, repeated debugging and verification are necessary, resulting in significant manpower and time costs. Utility Model Content

[0003] The problem solved by this invention is how to overcome the problem that in the prior art, the design of the drive circuit needs to be repeatedly debugged and verified when dealing with electromagnetic compatibility and other experiments, which increases a lot of manpower and time costs.

[0004] To address the aforementioned problems, this utility model provides a highly integrated constant current boost converter circuit at the automotive lighting board level, comprising: a boost topology module and a control chip; the boost topology module includes an inductor, a switching transistor, a diode, and an output capacitor, which are connected sequentially to form a boost energy conversion circuit; the control chip serves as the control chip for the boost energy conversion circuit; the boost topology module and the control chip are integrated on a printed circuit board; wherein, the switching transistor includes a core switching transistor, the input terminal of the inductor is connected to a DC power supply, the output terminal of the inductor is connected to the drain of the core switching transistor and the anode of the diode, the cathode of the diode is connected to the output capacitor, and the output terminal of the output capacitor is connected to the LED load of the automotive lighting; the control chip includes a gate drive pin, which is connected to the gate of the core switching transistor and is used to output a control signal to drive the core switching transistor to conduct.

[0005] The technical effects achieved by adopting this solution are as follows: Compared with existing technologies, the integrated design makes the overall circuit structure more compact, and the relative positions of each component are fixed. During electromagnetic compatibility experiments, there is no need for frequent repeated debugging and verification of the dispersed drive circuit sections, significantly reducing manpower and time costs. Integration onto the same printed circuit board helps optimize circuit layout, shorten signal transmission paths, and reduce the generation and impact of electromagnetic interference, thereby enhancing the stability and reliability of the circuit in electromagnetic environments. The boost energy conversion circuit formed by the sequential connection of the inductor, core switch, diode, and output capacitor in the boost topology module, combined with the precise control of the control chip, can efficiently boost the DC power supply voltage to power the LED load of the vehicle headlights. While achieving constant current output, it reduces energy loss and improves energy utilization efficiency. The control signal output from the gate drive pin can precisely adjust the on and off timing and duration of the core switch, ensuring that the core switch operates according to the preset timing and duty cycle, guaranteeing the stable and efficient operation of the boost energy conversion circuit and providing continuous and stable power to the LED load of the vehicle headlights. By precisely controlling the conduction state of the core switching transistor, the energy storage and release process of the inductor can be effectively matched, allowing the inductor to achieve optimal energy conversion efficiency in the "energy storage-energy release" cycle, reducing energy loss during the conversion process, and improving the energy utilization efficiency of the entire boost converter circuit.

[0006] Furthermore, the control chip also includes a negative current detection pin and a positive current detection pin; a current sampling unit, which includes a sampling resistor, with the negative current detection pin connected to one end of the sampling resistor and the positive current detection pin connected to the other end of the sampling resistor.

[0007] The technical effects achieved by adopting this solution are as follows: By connecting the negative and positive pins of the current detection to the two ends of the sampling resistor, the current signal flowing through the sampling resistor can be accurately acquired. This signal corresponds to the operating current of the core switching transistor and the LED load of the vehicle headlight, providing accurate current feedback for the control chip. Based on the acquired current signal, the control chip can adjust the control signal output by the gate drive pin in real time, thereby adjusting the conduction state of the core switching transistor. This stabilizes the operating current of the LED load near the set reference value, achieving precise constant current control and ensuring the consistency and stability of the headlight's brightness.

[0008] Furthermore, the control chip also includes a current adjustment pin, a frequency setting pin, and a slope compensation pin; the automotive headlight board-level highly integrated constant current boost converter circuit includes: an external fixing circuit, which is equipped with a current setting resistor, which is connected to the current adjustment pin and is used to adjust the reference operating current of the LED load by adjusting the resistance value.

[0009] The technical effects achieved by adopting this solution are as follows: By directly connecting the current setting resistor to the current adjustment pin and utilizing the quantitative correspondence between the resistor value and the reference current, the accuracy of the reference operating current controlling the LED load can be ensured, guaranteeing the stability of the reference current under different operating conditions and ensuring the consistency of vehicle headlight brightness from the source. Simply by changing the current setting resistor with different values, the load requirements of LEDs with different power can be quickly matched without modifying the circuit topology or control program, significantly improving the circuit's versatility for multiple vehicle models and multiple headlight groups, and reducing the development cost of dedicated circuits.

[0010] Furthermore, the peripheral fixed circuit also includes a frequency setting resistor, which is connected to the frequency setting pin and is used to set the switching frequency of the switching transistor by the resistance value.

[0011] The technical effects achieved by adopting this solution are as follows: By selecting frequency-setting resistors with different resistance values, the switching frequency of the switching transistor can be precisely set, enabling the circuit to adapt to the energy conversion requirements of different power LED loads in automotive lights and ensuring optimal energy conversion efficiency during the boost process. The fixed frequency setting method avoids frequency drift caused by external environmental factors (such as voltage fluctuations and temperature changes), reduces electromagnetic interference caused by frequency instability, and ensures compatibility between the circuit and other automotive electronic systems. Switching frequency adjustment can be achieved using only a single frequency-setting resistor, without modifying the complex circuit topology, simplifying the circuit parameter adjustment process and facilitating rapid frequency parameter calibration during the production stage based on actual needs.

[0012] Furthermore, the peripheral fixed circuit also includes: a slope compensation resistor, which is connected to the slope compensation pin and is used to achieve slope compensation of the current loop through the resistance value, thereby suppressing the subharmonic oscillation of the circuit.

[0013] The technical effects achieved by adopting this solution are as follows: By adjusting the resistance value of the slope compensation resistor, the compensation slope of the current loop can be precisely set, effectively suppressing subharmonic oscillations that may occur in the continuous conduction mode, and ensuring the stable operation of the switching transistor. The stable current loop characteristics prevent periodic fluctuations in the circuit output current, ensuring a continuous and stable drive current for the LED load and reducing instability in light emission caused by current fluctuations. Optimized compensation of the current loop can be achieved simply by adjusting the resistance value of a single resistor, without modifying the complex loop feedback structure, simplifying the circuit stability debugging process and facilitating unified parameter calibration during mass production.

[0014] Furthermore, the automotive headlight board-level highly integrated constant current boost converter circuit also includes: The sampling resistor has one end connected to the source of the core switching transistor and the other end grounded.

[0015] The technical effects achieved by adopting this solution are as follows: A complete current detection loop is formed. When the core switch is turned on, the current flows through the source of the core switch, through the sampling resistor, and grounded, creating a voltage difference across the sampling resistor that is proportional to the loop current. This provides the physical basis for the control chip to detect the current through the CSN / CSP pins. The sampling resistor converts the loop current into a detectable voltage signal, enabling real-time monitoring of the LED load's operating current. This provides accurate feedback for the control chip to adjust the core switch's on / off state and maintain constant current output. Since the sampling resistor is directly connected in series in the main current path, it accurately reflects the circuit's operating current, ensuring the accuracy of the detection signal and thus guaranteeing the stability of the LED load's operating current.

[0016] Furthermore, the printed circuit board employs a multilayer board design to reduce electromagnetic interference in the circuit.

[0017] The technical effects achieved by adopting this solution are as follows: Through the independent grounding and power plane design of the multilayer board, a low-impedance grounding and power supply path can be constructed, reducing electromagnetic coupling interference between different modules in the circuit caused by poor grounding and power fluctuations. This reduces the impact of interference signals on key components such as control chips and current sampling units. The compact structure of the multilayer board shortens the connection path between key components, reduces electromagnetic radiation generated during high-frequency signal transmission, and weakens the interference of the external electromagnetic environment on the internal circuit through the shielding effect of the metal plane, improving the overall electromagnetic compatibility performance of the circuit and adapting it to the complex electromagnetic environment of automobiles.

[0018] Furthermore, the control chip also includes a chip power supply pin and a ground pin; the constant current boost converter circuit also includes a filter capacitor, which is arranged close to the chip power supply pin and the ground pin to filter out high-frequency noise at the power input terminal.

[0019] The technical effects achieved by adopting this solution are as follows: It can directly filter out high-frequency noise mixed in the power signal input to the control chip, avoiding noise interference with the core modules such as the reference voltage and oscillation circuit inside the control chip, and ensuring the stability and reliability of key signals such as the switching drive signal and current detection signal output by the control chip. Placing the filter capacitor close to the chip's power and ground pins shortens the connection path between the capacitor and the pins, reduces the impact of parasitic inductance on the filtering effect, improves the filtering efficiency of high-frequency noise, and ensures the stable operation of the control chip in the complex power environment of an automotive system.

[0020] Furthermore, the output capacitor consists of multiple capacitors connected in parallel and is located at the input terminal of the LED load to stabilize the output voltage and reduce output ripple.

[0021] The technical effects achieved by adopting this solution are as follows: Connecting multiple capacitors in parallel increases the total capacitance of the output capacitor. Combined with their close proximity to the LED load input, this allows for a rapid response to current changes in the LED load, effectively suppressing instantaneous fluctuations in the output voltage. This provides a stable operating voltage for the LED load, ensuring uniform and stable brightness and preventing flickering or sudden brightness changes. The parallel capacitor combination structure, through the complementary characteristics of different capacitors, more comprehensively filters out ripple components in the output voltage, significantly reducing the output ripple amplitude and minimizing its impact on the LED load's lifespan. Simultaneously, it prevents ripple interference with the normal operation of other modules in the circuit.

[0022] In summary, the above-mentioned technical solutions of this application can have one or more of the following advantages or beneficial effects: i) By integrating the boost topology module, control chip, and peripheral fixed circuits onto the same printed circuit board and fixing the component positions, a highly integrated structure is formed. This allows for adaptation to different power and lighting scenarios of automotive LED loads by adjusting the current setting resistor and frequency setting resistor without overall modification. Furthermore, the standardized design enables mass production independently of projects, significantly reducing production and procurement costs. ii) Relying on the anti-interference structure of the multi-layer board design, the high-frequency noise filtering function of the filter capacitor, the optimized routing of the inductor and switching transistor, and the suppression of circuit oscillation by the slope compensation resistor, electromagnetic interference and radiation are significantly reduced, reducing the need for repeated debugging in electromagnetic compatibility experiments, shortening the R&D cycle, and adapting to the complex electromagnetic environment of automobiles. iii) Each functional module (such as current setting, frequency adjustment, and slope compensation) achieves parameter adjustment through a single resistor or standardized component, without requiring modification of the complex topology; the parallel output structure of multiple capacitors reduces the risk of single component failure, requiring only targeted replacement of faulty components during later maintenance, reducing overall maintenance costs and difficulty. Attached Figure Description

[0023] Figure 1 This is a framework diagram of a highly integrated constant current boost converter circuit at the automotive headlight board level, as described in this utility model embodiment. Figure 2 This is a schematic diagram of the boost constant current converter circuit at the automotive headlight board level in an embodiment of this utility model.

[0024] Explanation of reference numerals in the attached figures: 1-Boost topology module; 11-Inductor; 12-Switch transistor; 2-Control chip. Detailed Implementation

[0025] The purpose of this invention is to provide a highly integrated constant current boost converter circuit at the automotive headlight board level, which can improve the integration and standardization of the drive circuit, achieve partial decoupling of production and projects, and reduce procurement costs through mass production and bulk purchasing.

[0026] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0027] See Figures 1-2 This utility model provides a highly integrated constant current boost converter circuit at the automotive lighting board level, comprising: a boost topology module 1 and a control chip 2; the boost topology module 1 includes an inductor 11 (L3), a switching transistor 12, a diode (D1), and output capacitors (C19, C20), which are connected in sequence to form a boost energy conversion circuit; the control chip 2 serves as the control unit for the boost energy conversion circuit; the boost topology module 1 and the control chip 2 are integrated on a printed circuit board; wherein, the switching transistor 12 includes a core switching transistor, the input terminal of the inductor is connected to a DC power supply, the output terminal of the inductor is connected to the drain of the core switching transistor and the anode of the diode, the cathode of the diode is connected to the output capacitor, and the output terminal of the output capacitor is connected to the LED load of the automotive lighting; the control chip 2 includes a gate drive pin (GATE), which is connected to the gate of the core switching transistor and is used to output a control signal to drive the core switching transistor to conduct.

[0028] Specifically, boost topology module 1 refers to a boost circuit topology composed of inductor 11, switching transistor 12, diode, and output capacitor. It can be implemented using a BOOST architecture, using the periodic switching of switching transistor 12 to boost the input voltage and provide a stable operating voltage for the LED load. Control chip 2 refers to an integrated circuit with constant current control function, specifically a dedicated chip with a built-in PWM modulator. Control chip 2 (TPS92692) serves as the core control chip 2 of the constant current boost converter in this application. The operating state of switching transistor 12 is controlled by outputting a drive signal through the GATE pin, while the voltage difference across the sampling resistor is monitored through the CSN and CSP pins to achieve current closed-loop control. The current sampling unit is a component used to detect the loop current. Specifically, a low-resistance precision resistor can be connected in series between the source of switching transistor 12 and ground, and the real-time current value is obtained by measuring the voltage difference across the resistor. The peripheral fixed circuit refers to the circuit network that works with control chip 2 to set parameters. Specifically, it can be connected to specific pins of the chip through a resistor network to preset the current reference, switching frequency, and compensation parameters, avoiding external debugging.

[0029] Connecting the input terminal of inductor 11 to the DC power supply (VIN) means directly connecting inductor 11 to the positive terminal of the power input. This can be achieved using copper foil traces or metallized vias, shortening the current transmission path and reducing line impedance. Connecting the output terminal of inductor 11 to the drain of the core switch 12 and the anode of the diode means simultaneously connecting the output terminal of inductor 11 to the power input terminal of the core switch 12 and the conduction terminal of the diode. This can be achieved using a star-node layout, used to synchronously control the boost process and rectification. Connecting the diode cathode to the output capacitor means directly introducing the rectified current into the energy storage element. This can be achieved using a surface-mount ceramic capacitor in parallel with an electrolytic capacitor, used to absorb voltage fluctuations and maintain stable output voltage. Connecting the output capacitor to the LED load means delivering filtered power to the load. This can be achieved using wide copper strips or high-current connectors, used to reduce line voltage drop and improve current transmission efficiency. The DC power supply provides power to the boost circuit through the input terminal of inductor 11. In the two branches branched from the output terminal of inductor 11, the drain of the core switching transistor 12 forms a discontinuous current mode through periodic on / off switching, while the anode of the diode conducts freewheeling current during the off-state of transistor 12. Together, they complete the boost conversion. The connection between the diode cathode and the output capacitor forms a rectifier and filter circuit, eliminating voltage spikes caused by switching actions through capacitor charging and discharging. Finally, the output capacitor provides a smooth DC voltage to the LED load. The connection paths between components are controlled to the shortest distance through topology optimization, reducing parasitic parameters in the power circuit and improving the compactness of the circuit layout.

[0030] Switch 12 includes a core switch 12 and an auxiliary switch 12. The core switch 12 (NMOS): directly driven by the 2GATE pin of the control chip, it performs the core function of periodic on / off switching, and works with inductor 11 to complete the "energy storage-energy release" boost conversion, making it a key execution element in the main energy circuit. The auxiliary switch 12 (PMOS): as an auxiliary control element, it optimizes path characteristics (such as reducing conduction losses and cooperating with protection logic for fast turn-off), and does not participate in main energy conversion or current sampling.

[0031] See Figures 1-2 The control chip 2 also includes a current detection negative terminal pin (CNS) and a current detection positive terminal pin (CSP); a current sampling unit, which includes a sampling resistor, with the current detection negative terminal pin connected to one end of the sampling resistor and the current detection positive terminal pin connected to the other end of the sampling resistor.

[0032] Specifically, the operating state of switch 12 is controlled by outputting a drive signal through the GATE pin, while the voltage difference across the sampling resistor is monitored through the CSN and CSP pins to achieve closed-loop current control. The input terminal of inductor 11 is connected to VIN, and its output terminal is connected to the drain of switch 12 and the anode of diode, respectively. The cathode of diode is connected to the output capacitor and then to the LED load. The source of switch 12 is connected to one end of the sampling resistor, and the other end is grounded to form a current detection loop. Control chip 2 outputs a pulse signal through the GATE pin to drive switch 12 to conduct, and simultaneously acquires the voltage difference signal across the sampling resistor in real time through the CSN and CSP pins, adjusting the duty cycle of the drive signal to maintain constant current output.

[0033] See Figures 1-2 The control chip also includes a current adjustment pin (IADJ), a frequency setting pin (RT), and a slope compensation pin (SLOPE); the automotive headlight board-level highly integrated constant current boost converter circuit includes: an external fixing circuit, which is equipped with a current setting resistor (R5), which is connected to the current adjustment pin (IADJ) and is used to adjust the reference operating current of the LED load by adjusting the resistance value.

[0034] Specifically, the IADJ pin is the interface terminal on control chip 2 used to receive external current reference adjustment signals. It can be implemented using a voltage follower or differential amplifier circuit to convert the resistance value of the external resistor into a corresponding current reference signal. The current setting resistor is a fixed-value component connected between the IADJ pin and the reference ground. It can be implemented using a precision metal film resistor or an adjustable potentiometer, and its resistance value is linearly related to the reference operating current of the LED load. Control chip 2 detects the voltage difference across the current setting resistor via the IADJ pin and converts this voltage signal into an internal reference current value. When adjusting the operating current of the LED load, only the current setting resistor with a different resistance value needs to be replaced; no modification to the internal circuitry or PCB layout of control chip 2 is required. The change in the resistance value of the current setting resistor directly alters the input voltage range of the IADJ pin, which in turn adjusts the PWM duty cycle through the chip's internal error amplifier, ultimately achieving precise control of the output current.

[0035] See Figures 1-2 The peripheral fixed circuit also includes: a frequency setting resistor (R4), which is connected to the frequency setting pin (RT) and is used to set the switching frequency of the switching transistor by the resistance value.

[0036] Specifically, during circuit operation, the resistance value of the frequency setting resistor is converted into a corresponding voltage or current signal and input to the RT pin. The control chip 2 adjusts the oscillation frequency of the PWM modulator based on this signal. When adapting to the electromagnetic compatibility requirements of different vehicle models, only the frequency setting resistor with a different resistance value needs to be replaced; there is no need to modify the circuit topology or redesign the control logic. For example, when encountering high-frequency interference problems, the switching frequency can be reduced by increasing the resistance value, thereby reducing electromagnetic radiation; while when it is necessary to increase power density, the switching frequency can be increased by decreasing the resistance value, thereby reducing the size of the magnetic components.

[0037] Preferably, the switching frequency range set by connecting the RT pin of the TPS92692 control chip 2 to ground via a resistor is 80-800kHz.

[0038] See Figures 1-2 The peripheral fixed circuit also includes: a slope compensation resistor (R17), which is connected to the slope compensation pin (SLOPE) and is used to achieve slope compensation of the current loop through the resistance value to suppress the subharmonic oscillation of the circuit.

[0039] Specifically, the slope compensation resistor is a resistive element configured to form an electrical connection with the SLOPE pin of control chip 2. It can be implemented using a surface-mount resistor or a thin-film resistor, and its resistance range can be matched according to the system operating frequency and the parameters of inductor 11 to adjust the compensation strength of the current loop. The SLOPE pin is a dedicated interface on control chip 2 for receiving external compensation signals. It can be configured as a voltage-mode or current-mode input port to convert the resistance value information of the external resistor into an internal slope compensation amount. During the conduction of switching transistor 12, the difference between the rising slope of the current in inductor 11 and the falling slope during the turn-off period causes phase lag in the current loop. When the duty cycle exceeds a critical value, this phase lag will induce subharmonic oscillations. By connecting the slope compensation resistor through the SLOPE pin, the slope generator inside control chip 2 will superimpose a compensation amount proportional to the duty cycle onto the current sampling signal. The superimposed signal corrects the equivalent slope of the current loop, thereby disrupting the phase condition required for subharmonic oscillations.

[0040] See Figures 1-2 The automotive headlight board-level highly integrated constant current boost converter circuit also includes: a sampling resistor (R1), one end of which is connected to the source of the core switching transistor, and the other end of which is grounded.

[0041] Specifically, connecting the source of the core switch 12 to one end of the sampling resistor means directly connecting the current output terminal of the core switch 12 to the input terminal of the sampling resistor. This can be achieved using low-impedance metal traces. This connection ensures that all current flowing through the core switch 12 passes through the sampling resistor, forming a complete current detection path. Grounding the other end of the sampling resistor means connecting its output terminal to the circuit reference ground plane. This can be achieved using a short-path grounding design. This grounding method provides a low-impedance return path for the current detection loop and suppresses high-frequency noise interference to the sampling signal by reducing the loop impedance. During the operation of the boost converter, when the core switch 12 is turned on, the energy storage current in the inductor 11 flows through the source of the core switch 12 and is entirely discharged to ground through the sampling resistor. The voltage difference generated across the sampling resistor directly reflects the current value flowing through the core switch 12. This voltage signal is captured by the current sampling unit of the control chip 2 and used to adjust the duty cycle of the core switch 12 in real time, thereby achieving closed-loop control of the output current. Since the sampling resistor is directly connected in series between the source of the core switching transistor 12 and ground, there is no need to introduce additional isolation components or compensation circuits. This reduces the structural complexity of the current detection circuit and avoids the electromagnetic compatibility problems caused by the dispersed layout of compensation components in traditional current detection circuits.

[0042] See Figures 1-2 The printed circuit board uses a multi-layer board design to reduce electromagnetic interference in the circuit.

[0043] Specifically, multilayer design refers to forming a composite structure by stacking multiple conductive and insulating layers, which can be achieved using a four- or six-layer board structure. Each layer carries circuit traces with different functions. Independent ground and power layers are covered by large areas of copper foil to form low-impedance loops and electromagnetic shielding structures. Layered routing technology distributes analog control signals and power signals on different conductive layers, using insulating layers to achieve physical isolation. Ground and power layers serve as reference planes, absorbing common-mode noise generated by high-frequency switching signals and reducing radiated interference. The routing paths of critical power loops are shortened, reducing the impact of parasitic inductance 11 on voltage spikes during the switching process of the core switch 12, thereby suppressing conducted interference. The layered layout of analog control signals and power signals prevents digital noise from entering the control loop through spatial coupling, ensuring loop stability. This design allows the circuit to maintain electromagnetic compatibility in a compact space without needing to readjust the layout for different mounting structures.

[0044] See Figures 1-2 The control chip 2 also includes a chip power supply pin (VCC) and a ground pin (GND); the constant current boost converter circuit also includes a filter capacitor, which is arranged close to the VCC and GND pins to filter out high-frequency noise at the power input.

[0045] Specifically, the VCC pin refers to the power input interface of control chip 2, which can be connected to an external power supply using a metal pin to receive the external power supply voltage. The GND pin refers to the ground interface of control chip 2, which can be connected to the ground plane of the circuit board using a metal pin to establish a reference potential. The filter capacitor refers to a capacitor with high-frequency filtering function, which can be implemented using ceramic capacitors or film capacitors, and is used to form a low-impedance loop at the power input terminal. The VCC and GND pins of control chip 2 are critical nodes for power input, and their voltage stability directly affects the working state of the internal logic circuit of the chip. When the core switching transistor 12 switches rapidly, high-frequency current fluctuations are generated in the power supply line. These fluctuations form voltage spikes through the parasitic inductance 11 of the pin. By physically placing the filter capacitor close to the VCC and GND pins, the wire length between the capacitor and the pin is controlled within the millimeter range. This layout reduces the equivalent series inductance 11 of the capacitor to the nanohenry level, so that high-frequency noise is bypassed to the ground plane by the low-impedance path of the capacitor before reaching control chip 2.

[0046] For example, when the switching frequency reaches 500kHz, the impedance of the capacitor can be reduced to below 1Ω in the target frequency band, thereby effectively suppressing common-mode interference on the power line.

[0047] See Figures 1-2 The output capacitor consists of multiple capacitors connected in parallel and is located at the input terminal of the LED load of the vehicle headlight to stabilize the output voltage and reduce output ripple.

[0048] Specifically, the output capacitor consists of multiple capacitors connected in parallel, meaning that at least two capacitors are connected in parallel to form a composite filter structure. This can be achieved using a combination of ceramic and electrolytic capacitors. The ceramic capacitors absorb high-frequency ripple, while the electrolytic capacitors smooth low-frequency fluctuations. Placing the capacitor bank at the input of the LED load means directly soldering the parallel capacitor bank between the positive input terminal of the LED load and ground. This can be achieved by shortening the length of the conductor between the capacitor bank and the load, thereby reducing the loop impedance. Multiple parallel capacitors, by stacking their capacitance and reducing the equivalent series resistance, enhance the response capability to instantaneous current changes caused by the operation of the core switch 12. When the core switch 12 is turned on or off, the parallel capacitor bank absorbs voltage fluctuations through rapid charging and discharging, preventing significant voltage drops or spikes at the output. Simultaneously, the capacitor bank's close proximity to the LED load filters out high-frequency noise before it reaches the load, thus reducing the impact of current ripple on the LED's luminous stability.

[0049] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A highly integrated constant current boost converter circuit at the automotive headlight board level, characterized in that, include: The boost topology module (1) includes an inductor (11), a switching transistor (12), a diode, and an output capacitor. The inductor (11), the switching transistor (12), the diode, and the output capacitor are connected in sequence to form a boost energy conversion circuit. The control chip (2) serves as the control unit of the boost energy conversion circuit; the boost topology module (1) and the control chip are integrated on a printed circuit board; The switching transistor (12) includes a core switching transistor. The input terminal of the inductor (11) is connected to a DC power supply. The output terminal of the inductor (11) is connected to the drain of the core switching transistor and the anode of the diode. The cathode of the diode is connected to the output capacitor. The output terminal of the output capacitor is connected to the load of the vehicle light-emitting diode. The control chip (2) includes a gate drive pin. The gate drive pin is connected to the gate of the core switching transistor and is used to output a control signal to drive the core switching transistor to conduct.

2. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 1, characterized in that, The control chip (2) further includes a current detection negative terminal pin and a current detection positive terminal pin; a current sampling unit, the current sampling unit including a sampling resistor, the current detection negative terminal pin being connected to one end of the sampling resistor, and the current detection positive terminal pin being connected to the other end of the sampling resistor.

3. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 1, characterized in that, The control chip (2) also includes a current adjustment pin, a frequency setting pin, and a slope compensation pin; the automotive headlight board-level high-integration constant current boost converter circuit includes: an external fixing circuit, the external fixing circuit is provided with a current setting resistor, the current setting resistor is connected to the current adjustment pin, and is used to adjust the reference working current of the light-emitting diode load by adjusting the resistance value.

4. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 3, characterized in that, The peripheral fixing circuit also includes: A frequency setting resistor is connected to a frequency setting pin and is used to set the switching frequency of the switching transistor (12) by means of the resistance value.

5. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 3, characterized in that, The peripheral fixing circuit also includes: A slope compensation resistor, connected to a slope compensation pin, is used to compensate the slope of the current loop through its resistance value, thereby suppressing subharmonic oscillations in the circuit.

6. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 1, characterized in that, The automotive headlight board-level highly integrated constant current boost converter circuit also includes: A sampling resistor, one end of which is connected to the source of the core switching transistor, and the other end of which is grounded.

7. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 1, characterized in that, The printed circuit board employs a multilayer board design to reduce electromagnetic interference in the circuit.

8. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 1, characterized in that, The control chip (2) also includes a chip power supply pin and a ground pin; the automotive headlight board-level highly integrated constant current boost converter circuit also includes: A filter capacitor is arranged close to the power supply pin and the ground pin of the chip to filter out high-frequency noise at the power input terminal.

9. The automotive headlight board-level highly integrated constant current boost converter circuit according to claim 1, characterized in that, The output capacitor consists of multiple capacitors connected in parallel and is located at the input terminal of the vehicle headlight LED load to stabilize the output voltage and reduce output ripple.

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