Single-channel PWM driving dimming and color adjusting circuit

Abstract

The utility model discloses a single -way PWM drive light modulation and color modulation circuit, including power module, control module, timing module, discharge detection circuit and data storage circuit. Power module converts commercial power into double -way DC voltage output, and the encoder of control module is connected to control chip, and the output single -way PWM control signal, and light modulation module is connected to the output current of cold and warm LED positive common contact according to PWM duty ratio adjustment, realizes the brightness control, and the color modulation module is connected to the complementary reverse adjustment of cold and warm LED negative electrode conduction intensity according to same PWM control signal, and when duty ratio increases, enhances cold light LED current and weakens warm light LED current, and when duty ratio reduces, enhances warm light LED current and weakens cold light LED current, realizes the synchronous switching of brightness and color temperature. The utility model solves the technical problem that double -way control operation is complicated, hardware is redundant and cannot natural linkage regulation brightness and color temperature in the prior art.

Description

Technical Field

[0001] This utility model relates to the field of power supply testing technology, and in particular to a single-channel PWM drive dimming and color-tuning circuit. Background Technology

[0002] Currently, most mainstream dimming and color-changing lighting fixtures adopt a dual-channel PWM control architecture, requiring independent channels to adjust brightness and color temperature separately. Users must frequently switch operating modes, repeatedly select dimming / color-changing states using physical buttons, or adjust the two parameters layer by layer through a complex app interface. This design leads to three inherent drawbacks: First, it requires two independent constant current drive circuits and MCU control channels, significantly increasing circuit complexity and material costs; second, the user experience is fragmented, especially in scenarios like bedside reading or getting up at night to help sleep, where fumbling for buttons to switch modes in dim environments is extremely inconvenient; third, the brightness and color temperature parameters are mechanically decoupled, failing to achieve the natural lighting effect of "high-brightness cool light for alertness, low-brightness warm light for sleep," thus weakening the synergistic regulatory value of light on physiological rhythms. Therefore, there is an urgent need for a single-channel PWM drive dimming and color-changing circuit that simultaneously controls brightness and color temperature, simplifies lighting fixture buttons, simplifies user operation, and reduces hardware costs. Utility Model Content

[0003] The main purpose of this invention is to propose a single-channel PWM driven dimming and color-tuning circuit, which aims to solve the technical problems of cumbersome operation, hardware redundancy, and inability to naturally link and adjust brightness and color temperature in the existing dual-channel control circuit.

[0004] To achieve the above objectives, the first aspect of this utility model proposes a single-channel PWM drive dimming and color tuning circuit, including a power supply module, a control module, a dimming module, and a color tuning module. The power supply module provides a DC operating voltage. The control module includes a control chip and an encoder. The encoder output is connected to the first input of the control chip, and the control chip outputs a single-channel PWM control signal. The dimming module's first input is connected to the control of the control chip, and its first output is connected to the common positive terminal of both the warm white LED and the cool white LED. It is configured to adjust the current at the output based on the duty cycle of the PWM control signal. The color-tuning module's first input is connected to the control of the control chip, and its second input is connected to the second output of the dimming module. The first output is connected to the negative terminal of the warm white LED, and the second output is connected to the negative terminal of the cool white LED. It is configured to adjust the conduction strength of the first and second outputs in a complementary and reverse manner based on the change in the duty cycle of the PWM control signal. When the duty cycle increases, the conduction strength of the second output increases while the conduction strength of the first output decreases; when the duty cycle decreases, the conduction strength of the first output increases while the conduction strength of the second output decreases.

[0005] Preferably, the dimming module includes a constant current driving chip, a first diode, and a first inductor; the first input terminal of the constant current driving chip is connected to the control terminal of the control chip, the second input terminal is connected to the output terminal of the power supply module, and the output terminal is connected to the anode of the first diode and the first terminal of the first inductor; the cathode of the first diode is connected to the common positive terminal of the warm white LED and the cool white LED; the second terminal of the first inductor is connected to the second input terminal of the color-tuning module.

[0006] Preferably, the dimming module further includes a first resistor, a second resistor, a third resistor, a first capacitor, and a second capacitor; the first input terminal of the constant current drive chip is connected to the control terminal of the control chip through the first resistor, and the second capacitor and the second resistor are connected in parallel between the first input terminal of the constant current drive chip and ground; the second input terminal of the constant current drive chip is connected to the output terminal of the power module through the third resistor, and the first capacitor is connected across the second input terminal of the constant current drive chip and ground.

[0007] Preferably, the dimming module further includes a third capacitor, a fourth capacitor, a fifth capacitor, a fourth resistor, and a fifth resistor; the first terminal of the third capacitor is connected to the cathode of the first diode, the second terminal of the third capacitor is connected to the first terminal of the fourth resistor, and the second terminal of the fourth resistor is connected to the anode of the first diode; the fourth capacitor is connected across the second terminal of the first inductor and ground; the first terminal of the fifth capacitor and the first terminal of the fifth resistor are connected to the common positive terminal of the warm white LED and the cool white LED, and the second terminal of the fifth capacitor and the second terminal of the fifth resistor are connected to the second terminal of the first inductor.

[0008] Preferably, the color tuning module includes a color tuning control chip, a sixth capacitor, and a sixth resistor; the first terminal of the sixth resistor is connected to the control terminal of the control chip, the first input terminal of the color tuning control chip is connected to the second terminal of the sixth resistor and the first terminal of the sixth capacitor, and the second terminal of the sixth capacitor is grounded; the second input terminal of the color tuning control chip is connected to the second output terminal of the dimming module, the first output terminal is connected to the negative terminal of the warm white LED, and the second output terminal is connected to the negative terminal of the cool white LED.

[0009] Preferably, the color tuning module further includes a second diode, a seventh capacitor, an eighth capacitor, a seventh resistor, and an eighth resistor; the third input terminal of the color tuning control chip is connected to the output terminal of the power module through the seventh resistor, and the fourth input terminal is connected to the output terminal of the power module through the eighth resistor; the cathode of the second diode and the first terminal of the seventh capacitor are connected to the third input terminal of the color tuning control chip, and the anode of the second diode and the second terminal of the seventh capacitor are grounded; the eighth capacitor is connected across the fourth input terminal of the color tuning control chip and ground.

[0010] Preferably, the system further includes a step-down module, which includes a step-down chip, a third diode, and a second inductor; the first input terminal of the step-down chip is connected to the output terminal of the power module, and the output terminal is connected to the cathode of the third diode and the first terminal of the second inductor; the anode of the third diode is grounded, and the second terminal of the second inductor outputs a low-voltage DC operating voltage.

[0011] Preferably, the step-down module further includes a ninth capacitor, a tenth capacitor, an eleventh capacitor, a ninth resistor, and a tenth resistor; the ninth capacitor is connected across the first input terminal of the step-down chip and ground; the first terminal of the tenth capacitor is connected to the first terminal of the second inductor, the second terminal is connected to the first terminal of the ninth resistor, and the second terminal of the ninth resistor is grounded; the first terminal of the eleventh capacitor and the first terminal of the tenth resistor are connected to the second terminal of the second inductor, and the second terminal of the eleventh capacitor and the second terminal of the tenth resistor are grounded.

[0012] Preferably, the power module includes a power management chip, an input filter and rectifier circuit, a transformer, and an output filter and rectifier circuit; the input terminal of the input filter and rectifier circuit is connected to the mains power, and the output terminal is connected to the first input terminal of the power management chip and the first input terminal of the main winding of the transformer; the output terminal of the power management chip is connected to the second input terminal of the main winding of the transformer; the output terminal of the secondary winding of the transformer is connected to the input terminal of the output filter and rectifier circuit, and the output terminal of the output filter and rectifier circuit outputs a DC operating voltage.

[0013] Preferably, the power module further includes an eleventh resistor, a twelfth resistor, a twelfth capacitor, a fourth diode, and a fifth diode; the first end of the twelfth capacitor is connected to the first input terminal of the transformer main winding, the second end of the twelfth capacitor is connected to the cathode of the fourth diode through the eleventh resistor, and the anode of the fourth diode is connected to the second input terminal of the transformer main winding; the first end of the transformer auxiliary winding is connected to the anode of the fifth diode through the twelfth resistor, the cathode of the fifth diode is connected to the first input terminal of the power management chip, and the second end of the transformer auxiliary winding is grounded.

[0014] This invention proposes a single-channel PWM-driven dimming and color-tuning circuit. It synchronously controls the dimming and color-tuning modules via a single PWM control signal, completely eliminating mode switching buttons and simplifying user operation. The dimming module directly adjusts the total LED current, achieving stepless brightness variation. The color-tuning module uses complementary reverse conduction intensity adjustment of cool / warm LEDs to ensure stepless color temperature switching synchronously with brightness. A collaborative design connecting the second input of the color-tuning module to the output of the dimming module establishes a natural positive correlation between brightness and color temperature, with high brightness corresponding to high color temperature and low brightness to low color temperature, improving the light's adaptability to human circadian rhythms. The single-channel PWM control signal synchronously drives the dimming and color-tuning functions, improving system integration and reducing the number of control lines.

[0015] Furthermore, this invention improves the stability of the dimming current and eliminates flicker through a Buck topology design of the constant current drive chip and inductor diode; achieves real-time synchronization of brightness and color temperature control by directly connecting the output of the first inductor to the color tuning module; improves the duty cycle recognition accuracy of the constant current chip by using a current-limiting resistor and a filter capacitor in parallel with the PWM control signal; ensures the stability of the operating voltage of the constant current drive chip by using a decoupling capacitor and a current-limiting resistor on the VDD pin; enhances the freewheeling current resistance to voltage surges by using an RC spike absorption circuit on the first diode; improves the current smoothness and suppresses flicker by using a filter capacitor bank in parallel with the LED output; improves the anti-interference capability of the color temperature duty cycle resolution by using an RC grounding filter on the PWM pin of the color tuning control chip; ensures the authenticity of current sampling and response speed by directly connecting the VS pin of the color tuning control chip to the inductor output; and improves the brightness and color temperature control by using a VC pin. The C-pin Zener diode provides precise clamping, enhancing the logic circuit's resistance to voltage fluctuations; the VH-pin high-frequency filter capacitor optimizes MOSFET drive efficiency and reduces radiation; the combination of a freewheeling diode and inductor in the buck module improves voltage conversion efficiency; direct power supply to the control module via the buck inductor output ensures MCU power supply reliability; filtering via the buck input capacitor blocks conducted interference to prevent false triggering; a parallel RC circuit at the buck output enables rapid charge discharge to meet safety regulations; the varistor and fuse in the power input stage work together to enhance surge protection; precise control of the flyback topology transformer's energy transfer optimizes system efficiency and reduces temperature rise; the RCD clamping circuit absorbs leakage inductance spikes, protecting the main switch from breakdown damage; and direct power supply to the chip's VCC pin via auxiliary winding rectification eliminates startup failures and reduces standby power consumption.

[0016] In summary, this utility model solves the technical problems of cumbersome dual-channel control operation, hardware redundancy, and inability to naturally adjust brightness and color temperature in the prior art. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a block diagram illustrating the circuit principle of a single-channel PWM-driven dimming and color-tuning circuit according to this utility model.

[0019] Figure 2 This is a circuit diagram of the power module of this utility model;

[0020] Figure 3 This is a circuit diagram of the control module of this utility model;

[0021] Figure 4 This is a circuit diagram of the dimming module and color-tuning module of this utility model;

[0022] Figure 5 This is the circuit diagram of the step-down module of this utility model.

[0023] In the attached diagram: 1-Power supply module, 2-Control module, 3-Dimming module, 4-Color adjustment module, 5-Step-down module.

[0024] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0026] It should be noted that if the embodiments of this utility model involve directional indicators, such as up, down, left, right, front, back, etc., the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0027] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0028] The main purpose of this invention is to propose a single-channel PWM driven dimming and color-tuning circuit, which aims to solve the technical problems of cumbersome operation, hardware redundancy, and inability to naturally link and adjust brightness and color temperature in the existing dual-channel control circuit.

[0029] like Figures 1 to 5As shown, this utility model proposes a single-channel PWM drive dimming and color-tuning circuit, including a power supply module 1, a control module 2, a dimming module 3, and a color-tuning module 4. The power supply module 1 provides DC operating voltage to power the LEDs and other control chips. The control module 2 includes a control chip U3 and an encoder U5. The control chip U3 is an MC32F7073, and the encoder U5 is an EC11. The output terminal of the encoder U5 (see the A / B / ON node in the figure) is connected to the first input terminal of the control chip U3 (pins 15 / 14 / 7, used to receive A / B / ON signals). The control terminal of the control chip U3 (pin 9) outputs a single-channel PWM control signal. The first input terminal of the dimming module 3 is connected to the control terminal of the control chip U3 to obtain the PWM control signal, and the first output terminal is connected to the warm white LED and the cool white LED. The positive common contact is configured to adjust the current at the output terminal according to the duty cycle of the PWM control signal; the first input terminal of the color adjustment module 4 is connected to the control terminal of the control chip U3 to obtain the PWM control signal, the second input terminal is connected to the second output terminal of the dimming module 3, the first output terminal is connected to the negative terminal of the warm white temperature LED, and the second output terminal is connected to the negative terminal of the cool white temperature LED. It is configured to perform complementary and reverse adjustment of the conduction intensity of the first output terminal and the second output terminal according to the change of the duty cycle of the PWM control signal. When the duty cycle increases, the conduction intensity of the second output terminal is enhanced and the conduction intensity of the first output terminal is weakened. When the duty cycle decreases, the conduction intensity of the first output terminal is enhanced and the conduction intensity of the second output terminal is weakened. In this embodiment, a single PWM control signal synchronously drives the dimming module 3 and the color adjustment module 4, so that the rotation operation of the knob encoder U5 directly links and adjusts the brightness and color temperature: clockwise rotation increases the PWM duty cycle to achieve high-brightness cool light; counterclockwise rotation decreases the duty cycle to switch to low-brightness warm light. No mode switching button is required throughout the process, and the natural light effect of synchronously adjusting the brightness and color temperature can be achieved with a single rotation operation.

[0030] Understandably, this embodiment reduces hardware costs by more than 30% by controlling brightness and color temperature synchronously with a single PWM channel, thereby reducing one MCU pin and peripheral circuitry. It also eliminates the need for button switching by using a knob for stepless adjustment of dual parameters, improving user intuitiveness and ease of use in dim environments. Furthermore, it enhances the synergistic regulatory value of light on human circadian rhythms through the positive correlation logic matching of brightness and color temperature.

[0031] Preferred, see Figure 4As shown, in a specific embodiment of this utility model, the dimming module 3 includes a constant current drive chip U4, a first diode D5, and a first inductor T3. The constant current drive chip U4 is an OC5228. The first input terminal PWM pin of the constant current drive chip U4 is connected to the control terminal (pin 9) of the control chip U3 to obtain the PWM control signal. The second input terminal VDD pin is connected to the output terminal of the power supply module 1 to obtain the 12V voltage. The output terminal D pin is connected to the anode of the first diode D5 and the first terminal of the first inductor T3. The cathode of the first diode D5 is connected to the common junction of the positive terminals of the warm white LED and the cool white LED. The second terminal of the first inductor T3 is connected to the second input terminal of the color adjustment module 4, forming a constant current drive circuit.

[0032] Understandably, this embodiment improves the linear regulation accuracy of LED current by using the constant current chip U4 to accurately respond to changes in the PWM duty cycle; it improves the power conversion efficiency and eliminates flicker by using the freewheeling circuit formed by inductor T3 and diode D5; it improves the real-time coordination between brightness and color temperature control by directly connecting the output of the first inductor T3 to the second input of the color adjustment module; and it improves circuit reliability and reduces the risk of temperature rise by simplifying the power topology.

[0033] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, the constant current driver chip U4 can be replaced with other chips, such as PT4115, to be compatible with low-voltage application scenarios; or the Buck topology can be replaced with a linear constant current circuit to simplify low-power design; or a magnetic ring inductor can be used to replace T3 to optimize EMI characteristics.

[0034] Preferred, see Figure 4 As shown, in a specific embodiment of this utility model, the dimming module 3 further includes a first resistor R19, a second resistor R20, a third resistor R15, a first capacitor C10, and a second capacitor C9; the first input terminal PWM pin of the constant current drive chip U4 is connected to the control terminal (pin 9) of the control chip U3 through the first resistor R19 to obtain the PWM control signal; the second capacitor C9 and the second resistor R20 are connected in parallel between the first input terminal PWM pin of the constant current drive chip U4 and ground to filter out signal noise; the second input terminal VDD pin of the constant current drive chip U4 is connected to the output terminal of the power module 1 through the third resistor R15 to obtain a 12V voltage; the first capacitor C10 is connected across the second input terminal VDD pin of the constant current drive chip U4 and ground to achieve power decoupling and ensure stable chip operating voltage.

[0035] Understandably, this embodiment improves the anti-interference capability of PWM control signal transmission through current limiting protection by the first resistor R19; improves the PWM duty cycle recognition accuracy through parallel filtering of the second capacitor C9 and the second resistor R20; and improves the voltage stability of the constant current chip and suppresses power supply ripple through the decoupling combination of the third resistor R15 and the first capacitor C10.

[0036] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, the resistor can be replaced with a ferrite bead to suppress high-frequency noise; the capacitor can be replaced with a π-type filter circuit to enhance the filtering effect; or a constant current chip with integrated filtering function can be used to replace the peripheral circuit.

[0037] Preferably, as shown in Figure 4, in a specific embodiment of this utility model, the dimming module 3 further includes a third capacitor C6, a fourth capacitor C11, a fifth capacitor EC5, a fourth resistor R18, and a fifth resistor R17. The fifth capacitor EC5 is an electrolytic capacitor. The first end of the third capacitor C6 is connected to the cathode of the first diode D5, and the second end is connected to the first end of the fourth resistor R18. The second end of the fourth resistor R18 is connected to the anode of the first diode D5, forming a peak voltage absorption circuit to suppress switching peaks. The fourth capacitor C11 is connected across the second end of the first inductor T3 and ground to filter out inductor ripple. The first end (positive) of the fifth capacitor EC5 and the first end of the fifth resistor R17 are connected to the common positive junction LED+ of the warm white LED and the cool white LED. The second end (negative) of the fifth capacitor EC5 and the second end of the fifth resistor R17 are connected to the second end of the first inductor T3 to achieve output current smoothing and overvoltage protection, and to stabilize the LED operating current.

[0038] Understandably, in this embodiment, the spike voltage absorption circuit formed by the third capacitor C6 and the fourth resistor R18 in series improves the voltage surge resistance of the freewheeling diode D5 and extends its service life; the filtering effect of the fourth capacitor C11 on inductor ripple improves the power supply stability of the color tuning module 3 and eliminates color temperature jumps; the parallel combination of the EC5 electrolytic capacitor and the fifth resistor R17 improves the smoothness of the LED operating current and realizes overvoltage protection, thus jointly ensuring a constant LED operating current.

[0039] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, the peak absorption circuit can be replaced with a TVS diode to simplify the number of components; the fourth capacitor C11 can be replaced with a π-type LC filter to enhance high-frequency noise suppression; or a self-resetting fuse can be used to replace R17 to increase overcurrent protection.

[0040] Preferred, see Figure 4As shown, in a specific embodiment of this utility model, the color adjustment module 4 includes a color adjustment control chip U6, a sixth capacitor C14, and a sixth resistor R24. The color adjustment control chip U6 is a BP5926A. The first input terminal PWM pin of the color adjustment control chip U6 is connected to the control terminal (pin 9) of the control chip U3 through the sixth resistor R24 ​​to obtain the PWM control signal. The first input terminal PWM pin of the color adjustment control chip U6 is also grounded through the sixth capacitor C14 to filter out interference. The second input terminal VS pin of the color adjustment control chip U6 is connected to the second input terminal of the dimming module 3. The output terminal (i.e., the second terminal of the first inductor T3) is used to construct a floating ground reference point on the high-voltage side, so that the source potential of the MOSFET inside the chip floats synchronously with the potential of the LED circuit, thereby accurately detecting the total LED current and dynamically adjusting the cold / warm light output ratio through the internal comparator, ensuring that the total power is constant during color temperature switching and avoiding overcurrent damage; the first output terminal D2 of the color control chip U6 is connected to the negative terminal W-1 of the warm white LED, and the second output terminal D1 is connected to the negative terminal Y-1 of the cool white LED, realizing dual complementary output (constant total current) based on the same PWM control signal.

[0041] Understandably, this embodiment constructs a high-voltage side floating ground through the VS pin to improve the chip's tracking accuracy of the LED circuit potential and the switching safety; it detects the total LED current through the VS pin to improve the dynamic balance of the complementary adjustment of cold / warm light current; it improves noise suppression capability through RC filtering of the PWM pin to ensure duty cycle recognition accuracy; and it improves the smoothness of light switching and eliminates brightness jumps through the complementary output total current constant mechanism.

[0042] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, BP5926A can be replaced with BP5926D to be compatible with 24V power supply scenarios; or an external current sampling resistor + comparator can be used to replace the VS pin function to realize a custom protection threshold; or the C14 capacitor can be omitted to simplify the design.

[0043] Preferred, see Figure 4As shown, in a specific embodiment of this utility model, the color tuning module 4 further includes a second diode ZD1, a seventh capacitor C15, an eighth capacitor C16, a seventh resistor R21, and an eighth resistor R27; the third input terminal VCC pin of the color tuning control chip U6 is connected to the output terminal of the power module 1 through the seventh resistor R21 to obtain a 12V voltage, and the fourth input terminal VH pin is connected to the output terminal of the power module 1 through the eighth resistor R27 to obtain a 12V voltage; the cathode of the second diode ZD1 and the first terminal of the seventh capacitor C15 are connected to the third input terminal VCC pin of the color tuning control chip U6, and the anode of the second diode ZD1 and the second terminal of the seventh capacitor C15 are grounded to filter out low-frequency ripple; the eighth capacitor C16 is connected across the fourth input terminal VH pin of the color tuning control chip U6 and ground to suppress high-frequency switching noise of the VH pin and improve the driving stability of the internal MOSFET.

[0044] Understandably, this embodiment improves the power supply stability of the color control chip U6 and prevents overvoltage breakdown by using the precise clamping characteristics of the Zener diode; it improves the purity of the VCC pin voltage and eliminates the risk of false triggering by filtering out low-frequency ripple through the seventh capacitor C15; it improves the switching efficiency of the internal MOSFET and suppresses electromagnetic interference by using the high-frequency decoupling of the VH pin through the eighth capacitor C16; and it improves the short-circuit withstand capability of the high-voltage drive circuit and extends the chip life through the current limiting protection of the eighth resistor R27.

[0045] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, the ZD1 Zener diode can be replaced with a low dropout linear regulator (LDO) to improve energy efficiency; the capacitor can be replaced with a π-type LC filter network to enhance high-frequency noise suppression; or a self-resetting fuse can be used to replace the resistor to increase overcurrent protection.

[0046] Preferred, see Figure 5 As shown, in a specific embodiment of this utility model, a step-down module 5 is also included. The step-down module 5 includes a step-down chip U2 and a second inductor T2. The step-down chip U2 is an OC5864. The first input terminal IN pin of the step-down chip U2 is connected to the output terminal of the power supply module 1 to obtain a 12V voltage. The EN pin is pulled up to 12V by the enable resistor R14 and is enabled by default. The output terminal SW pin of the step-down chip U2 is connected to the cathode of the third diode D4 and the first terminal of the second inductor T2. The FB pin of the step-down module 5 is connected to the voltage divider feedback resistors R13 / R16. The anode of the third diode D4 is grounded. The second terminal of the second inductor T2 outputs a low-voltage DC working voltage of 5V, which is used to power the control chip U3 and the encoder U5.

[0047] Understandably, this embodiment improves voltage conversion efficiency and reduces external components through high-frequency switching control of the step-down chip; reduces the reverse electromotive force impact of the second inductor T2 and suppresses electromagnetic interference through the fast freewheeling characteristic of the third diode D4; and improves the smoothness of the 5V output current and eliminates MCU power supply ripple through the energy storage and filtering design of the second inductor T2.

[0048] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, the step-down chip can be replaced from OC5864 to other step-down chips to be compatible with 24V input voltage; or a Schottky diode can be used to replace the third diode D4 to reduce the on-state voltage drop; or a planar inductor can be used to replace the wire-wound inductor T2 to optimize EMI characteristics; or an output filter capacitor bank can be added to extend the dynamic response speed.

[0049] Preferred, see Figure 5 As shown in a specific embodiment of this utility model, the step-down module 5 further includes a ninth capacitor C7, a tenth capacitor C3, an eleventh capacitor EC4, a ninth resistor R12, and a tenth resistor R11, wherein the eleventh capacitor EC4 is an electrolytic capacitor; the ninth capacitor C7 is connected across the first input terminal IN pin of the step-down chip U2 and ground to filter out high-frequency ripple of the 12V input; the first end of the tenth capacitor C3 is connected to the first end of the second inductor T2, the second end is connected to the first end of the ninth resistor R12, and the second end of the ninth resistor R12 is grounded, forming a spike voltage absorption circuit to suppress switching spikes; the first end (positive) of the eleventh capacitor EC4 and the first end of the tenth resistor R11 are connected to the second end of the second inductor T2, and the second end (negative) of the eleventh capacitor EC4 and the second end of the tenth resistor R11 are grounded L for energy storage filtering and charge discharge.

[0050] Understandably, this embodiment improves the chip's resistance to conducted interference and prevents false triggering by using the ninth capacitor C7 for high-frequency filtering of the input voltage; it improves the stability of the SW pin voltage and reduces electromagnetic radiation by forming a spike voltage absorption circuit through the series connection of the ground capacitor C3 and the ninth resistor R12; and it improves the transient response speed of the 5V output load and eliminates the risk of residual voltage after power failure by working together with the energy storage filtering of the eleventh capacitor EC4 and the charge discharge of the tenth resistor R11.

[0051] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, they can replace the single capacitor C9 with a multi-stage LC filter to enhance EMI suppression; replace EC4 with a solid capacitor to improve lifespan; or replace the spike absorption circuit with a TVS diode to simplify the layout.

[0052] Preferred, see Figures 1 to 2As shown in a specific embodiment of this utility model, the power module 1 includes a power management chip U1, an input filter and rectifier circuit, a transformer T1, and an output filter and rectifier circuit. The power management chip U1 is an S7134B. The input terminal of the input filter and rectifier circuit is connected to the mains power, and the output terminal is connected to the first input terminal of the main winding N1 of the transformer T1. The first input terminal VCC pin of the power management chip U1 is connected to the output terminal of the input filter and rectifier circuit through resistors R4 / R6, and grounded through electrolytic capacitor EC3. Resistors R4, R6, and electrolytic capacitor EC3 together form a power transistor. The power management chip U1 has a startup circuit; the output pin C of the power management chip U1 is connected to the second input terminal of the transformer main winding N1, and the FB pin is connected to the first terminal of the transformer auxiliary winding N3 through a resistor divider network (R8-R10) to receive feedback voltage and achieve closed-loop voltage regulation; the CS pin is grounded through a parallel current sampling resistor (RS1 / RS2) to detect the switching current in real time and limit the maximum output power; the output terminal of the transformer T1 secondary winding N2 is connected to the input terminal of the output filter rectifier circuit, and the output terminal of the output filter rectifier circuit outputs a DC operating voltage of 12V. The input filtering and rectifier circuit consists of a varistor RV1, a fuse FR1, a toroidal inductor LF1, and a rectifier bridge BD1. The AC power line L is connected to the first input terminal of the toroidal inductor LF1 via the fuse FR1, and the AC power line N is connected to the second input terminal of the toroidal inductor LF1. The varistor RV1 is connected across the input side of the toroidal inductor LF1 to suppress surges. The output terminal of the toroidal inductor LF1 is filtered by a ferrite bead B1 and a capacitor CX1 and then connected to the AC input terminal of the rectifier bridge BD1. The positive DC output terminal of the rectifier bridge BD1 is connected to the first terminal of the transformer main winding N1 and the power supply circuit of the power management chip U1, while the negative output terminal is grounded, thus realizing AC to DC conversion and filtering out high-frequency interference. The output filtering and rectifier circuit consists of the secondary winding N2 of transformer T1, rectifier diode D1, filter capacitor EC1 / C1, and resistor R1. The first end of the secondary winding N2 is connected to the anode of rectifier diode D1 after being buffered by resistor R1 and capacitor C1 in parallel. The cathode of rectifier diode D1 is connected to the positive terminal of electrolytic capacitor EC1 and the other end of capacitor C1 to output 12V. The second end of the secondary winding N2 is grounded, and the negative terminal of electrolytic capacitor EC1 is grounded. The unidirectional conduction of rectifier diode D1 and the filtering of EC1 / C1 eliminate switching ripple and stabilize the output voltage.

[0053] Understandably, this embodiment improves the ability to resist lightning overvoltage and blocks power grid conducted interference through the multi-stage surge protection design of the input filter rectifier circuit; improves voltage conversion efficiency and reduces standby power consumption by precisely controlling the energy transfer of the main winding of transformer T1 through the power management chip U1; and improves LED driving stability and eliminates flickering through the low ripple characteristics of the secondary rectifier output.

[0054] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, they can replace U1 with an integrated high-voltage start-up power chip to eliminate the need for an external start-up circuit; or replace the output rectifier diode D1 with a synchronous rectification scheme to improve energy efficiency.

[0055] Preferred, see Figures 1 to 2 As shown, in a specific embodiment of this utility model, the power module 1 further includes an eleventh resistor R5, a twelfth resistor R7, a twelfth capacitor C2, a fourth diode D2, and a fifth diode D3; the first end of the twelfth capacitor C2 is connected to the first input terminal of the main winding N1 of transformer T1, and the second end is connected to the cathode of the fourth diode D2 through the eleventh resistor R5. The anode of the fourth diode D2 is connected to the second input terminal of the main winding N1 of transformer T1. The twelfth capacitor C2, the eleventh resistor R5, and the fourth diode D2 form an RCD clamping circuit, which is used to absorb the leakage inductance energy of the main winding N1 of transformer and suppress the opening. The voltage spike during turn-off protects the built-in MOSFET of the power management chip U1 from breakdown damage. The first terminal of the auxiliary winding N3 of transformer T1 is connected to the anode of the fifth diode D3 through the twelfth resistor R7. The cathode of the fifth diode D3 is connected to the first input terminal VCC of the power management chip U1. The second terminal of the auxiliary winding N3 of transformer T1 is grounded, which replaces the start-up resistor R4 / R6 to supply power after the power management chip U1 starts up. It provides a continuous and stable operating voltage for U1 through the rectifier diode D3 and the energy storage capacitor EC3, and simultaneously provides real-time feedback on the output voltage change to achieve closed-loop voltage regulation control. The FB pin of the power management chip U1 is connected to the first terminal of the auxiliary winding N3 of the transformer through a resistor divider network (R8-R10), which samples the output voltage change in real time and feeds it back to the internal error amplifier of the power management chip U1 to dynamically adjust the PWM duty cycle to achieve closed-loop voltage regulation control. The CS pin of the power management chip U1 is grounded through a parallel current sampling resistor (RS1 / RS2), which detects the main circuit switching current in real time and inputs it to the internal comparator to trigger the overcurrent protection mechanism to limit the maximum output power.

[0056] Understandably, this embodiment improves the main switch's resistance to voltage spikes and extends chip life by absorbing leakage inductance energy through the RCD clamping circuit (C2 / R5 / D2); and improves power supply stability and eliminates the risk of startup failure by directly supplying VCC pin through the auxiliary winding N3 rectified by the rectifier diode D3.

[0057] Based on the above technical solutions, those skilled in the art can make corresponding equivalent improvements according to the application scenario. For example, the fast recovery diode D2 of the RCD clamping circuit can be replaced with a TVS diode to simplify the layout; or an integrated overcurrent protection power chip can be used to replace the external sampling resistor of the CS pin; or a digitally adjustable resistor can be used to replace the voltage divider network R8-R10 to achieve dynamic setting of the output voltage.

[0058] Compared with the prior art, the beneficial effects of this utility model include at least the following:

[0059] This invention proposes a single-channel PWM-driven dimming and color-tuning circuit. It synchronously controls the dimming and color-tuning modules via a single PWM control signal, completely eliminating mode switching buttons and simplifying user operation. The dimming module directly adjusts the total LED current, achieving stepless brightness variation. The color-tuning module uses complementary reverse conduction intensity adjustment of cool / warm LEDs to ensure stepless color temperature switching synchronously with brightness. A collaborative design connecting the second input of the color-tuning module to the output of the dimming module establishes a natural positive correlation between brightness and color temperature, with high brightness corresponding to high color temperature and low brightness to low color temperature, improving the light's adaptability to human circadian rhythms. The single-channel PWM control signal synchronously drives the dimming and color-tuning functions, improving system integration and reducing the number of control lines.

[0060] Furthermore, this invention improves the stability of the dimming current and eliminates flicker through a Buck topology design of the constant current drive chip and inductor diode; achieves real-time synchronization of brightness and color temperature control by directly connecting the output of the first inductor to the color tuning module; improves the duty cycle recognition accuracy of the constant current chip by using a current-limiting resistor and a filter capacitor in parallel with the PWM control signal; ensures the stability of the operating voltage of the constant current drive chip by using a decoupling capacitor and a current-limiting resistor on the VDD pin; enhances the freewheeling current resistance to voltage surges by using an RC spike absorption circuit on the first diode; improves the current smoothness and suppresses flicker by using a filter capacitor bank in parallel with the LED output; improves the anti-interference capability of the color temperature duty cycle resolution by using an RC grounding filter on the PWM pin of the color tuning control chip; ensures the authenticity of current sampling and response speed by directly connecting the VS pin of the color tuning control chip to the inductor output; and improves the brightness and color temperature control by using a VC pin. The C-pin Zener diode provides precise clamping, enhancing the logic circuit's resistance to voltage fluctuations; the VH-pin high-frequency filter capacitor optimizes MOSFET drive efficiency and reduces radiation; the combination of a freewheeling diode and inductor in the buck module improves voltage conversion efficiency; direct power supply to the control module via the buck inductor output ensures MCU power supply reliability; filtering via the buck input capacitor blocks conducted interference to prevent false triggering; a parallel RC circuit at the buck output enables rapid charge discharge to meet safety regulations; the varistor and fuse in the power input stage work together to enhance surge protection; precise control of the flyback topology transformer's energy transfer optimizes system efficiency and reduces temperature rise; the RCD clamping circuit absorbs leakage inductance spikes, protecting the main switch from breakdown damage; and direct power supply to the chip's VCC pin via auxiliary winding rectification eliminates startup failures and reduces standby power consumption.

[0061] In summary, this utility model solves the technical problems of cumbersome dual-channel control operation, hardware redundancy, and inability to naturally adjust brightness and color temperature in the prior art.

[0062] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A single-channel PWM drive dimming and color-tuning circuit, characterized in that, include: Power module (1) is used to provide DC operating voltage; The control module (2) includes a control chip and an encoder. The output terminal of the encoder is connected to the first input terminal of the control chip, and the control terminal of the control chip outputs a single-channel PWM control signal. The dimming module (3) has a first input terminal connected to the control terminal of the control chip and a first output terminal connected to the common positive terminal of the warm white LED and the cool white LED. It is configured to adjust the current of the output terminal according to the duty cycle of the PWM control signal. The color adjustment module (4) has a first input terminal connected to the control terminal of the control chip, a second input terminal connected to the second output terminal of the dimming module (3), a first output terminal connected to the negative terminal of the warm white LED, and a second output terminal connected to the negative terminal of the cool white LED. It is configured to perform complementary reverse adjustment of the conduction intensity of the first output terminal and the second output terminal according to the change of the duty cycle of the PWM control signal. When the duty cycle increases, the conduction intensity of the second output terminal is enhanced and the conduction intensity of the first output terminal is weakened. When the duty cycle decreases, the conduction intensity of the first output terminal is enhanced and the conduction intensity of the second output terminal is weakened.

2. The single-channel PWM drive dimming and color tuning circuit as described in claim 1, characterized in that, The dimming module (3) includes a constant current driving chip, a first diode, and a first inductor; the first input terminal of the constant current driving chip is connected to the control terminal of the control chip, the second input terminal is connected to the output terminal of the power module (1), and the output terminal is connected to the anode of the first diode and the first terminal of the first inductor; the cathode of the first diode is connected to the common junction of the positive electrodes of the warm white LED and the cool white LED; the second terminal of the first inductor is connected to the second input terminal of the color-tuning module (4).

3. The single-channel PWM drive dimming and color tuning circuit as described in claim 2, characterized in that, The dimming module (3) further includes a first resistor, a second resistor, a third resistor, a first capacitor, and a second capacitor; the first input terminal of the constant current driving chip is connected to the control terminal of the control chip through the first resistor, and the second capacitor and the second resistor are connected in parallel between the first input terminal of the constant current driving chip and ground; the second input terminal of the constant current driving chip is connected to the output terminal of the power module (1) through the third resistor, and the first capacitor is connected across the second input terminal of the constant current driving chip and ground.

4. The single-channel PWM drive dimming and color tuning circuit as described in claim 2, characterized in that, The dimming module (3) further includes a third capacitor, a fourth capacitor, a fifth capacitor, a fourth resistor, and a fifth resistor; the first end of the third capacitor is connected to the cathode of the first diode, the second end of the third capacitor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is connected to the anode of the first diode; the fourth capacitor is connected across the second end of the first inductor and ground; the first end of the fifth capacitor and the first end of the fifth resistor are connected to the common positive terminal of the warm white LED and the cool white LED, and the second end of the fifth capacitor and the second end of the fifth resistor are connected to the second end of the first inductor.

5. The single-channel PWM drive dimming and color tuning circuit as described in claim 1, characterized in that, The color tuning module (4) includes a color tuning control chip, a sixth capacitor, and a sixth resistor; the first end of the sixth resistor is connected to the control terminal of the control chip, the first input terminal of the color tuning control chip is connected to the second end of the sixth resistor and the first end of the sixth capacitor, and the second end of the sixth capacitor is grounded; the second input terminal of the color tuning control chip is connected to the second output terminal of the dimming module (3), the first output terminal is connected to the negative electrode of the warm white temperature LED, and the second output terminal is connected to the negative electrode of the cool white temperature LED.

6. The single-channel PWM drive dimming and color tuning circuit as described in claim 5, characterized in that, The color tuning module (4) further includes a second diode, a seventh capacitor, an eighth capacitor, a seventh resistor, and an eighth resistor; the third input terminal of the color tuning control chip is connected to the output terminal of the power module (1) through the seventh resistor, and the fourth input terminal is connected to the output terminal of the power module (1) through the eighth resistor; the cathode of the second diode and the first terminal of the seventh capacitor are connected to the third input terminal of the color tuning control chip, and the anode of the second diode and the second terminal of the seventh capacitor are grounded; the eighth capacitor is connected across the fourth input terminal of the color tuning control chip and ground.

7. The single-channel PWM drive dimming and color tuning circuit as described in claim 1, characterized in that, It also includes a step-down module (5), which includes a step-down chip, a third diode and a second inductor; the first input terminal of the step-down chip is connected to the output terminal of the power module (1), and the output terminal is connected to the cathode of the third diode and the first terminal of the second inductor; the anode of the third diode is grounded, and the second terminal of the second inductor outputs a low-voltage DC working voltage.

8. The single-channel PWM drive dimming and color tuning circuit as described in claim 7, characterized in that, The step-down module (5) further includes a ninth capacitor, a tenth capacitor, an eleventh capacitor, a ninth resistor, and a tenth resistor; the ninth capacitor is connected across the first input terminal of the step-down chip and ground; the first end of the tenth capacitor is connected to the first end of the second inductor, the second end is connected to the first end of the ninth resistor, and the second end of the ninth resistor is grounded; the first end of the eleventh capacitor and the first end of the tenth resistor are connected to the second end of the second inductor, and the second end of the eleventh capacitor and the second end of the tenth resistor are grounded.

9. The single-channel PWM drive dimming and color tuning circuit as described in claim 1, characterized in that, The power module (1) includes a power management chip, an input filter rectifier circuit, a transformer, and an output filter rectifier circuit. The input terminal of the input filter rectifier circuit is connected to the mains power, and the output terminal is connected to the first input terminal of the power management chip and the first input terminal of the main winding of the transformer. The output terminal of the power management chip is connected to the second input terminal of the main winding of the transformer. The output terminal of the secondary winding of the transformer is connected to the input terminal of the output filter rectifier circuit, and the output terminal of the output filter rectifier circuit outputs a DC operating voltage.

10. The single-channel PWM drive dimming and color tuning circuit as described in claim 9, characterized in that, The power module (1) further includes an eleventh resistor, a twelfth resistor, a twelfth capacitor, a fourth diode, and a fifth diode; the first end of the twelfth capacitor is connected to the first input terminal of the transformer main winding, the second end of the twelfth capacitor is connected to the cathode of the fourth diode through the eleventh resistor, and the anode of the fourth diode is connected to the second input terminal of the transformer main winding; the first end of the transformer auxiliary winding is connected to the anode of the fifth diode through the twelfth resistor, the cathode of the fifth diode is connected to the first input terminal of the power management chip, and the second end of the transformer auxiliary winding is grounded.

Images