LED analog-digital hybrid dimming drive circuit

Abstract

The utility model relates to the field of dimming drive circuits, and particularly discloses an LED analog-digital hybrid dimming drive circuit, which comprises an MCU controller and a dimming drive chip, the low-side output end of the dimming drive chip is electrically connected with a power switch element, the power switch element is electrically connected with the negative electrode of an LED lamp through an inductance element, and the power switch element is electrically connected with the negative electrode of the LED lamp through the inductance element. The PWM output end of the MCU controller outputs digital signals to the PWM input end of the dimming driving chip, a digital-to-analog conversion integrating circuit is arranged between the IO output end of the MCU controller and the ADJ input end of the dimming driving chip, and the IO output end of the MCU controller outputs digital signals to the digital-to-analog conversion integrating circuit. The digital-to-analog conversion integrating circuit converts the digital signal into an analog signal and transmits the analog signal to the ADJ input end of the dimming driving chip.

Description

An LED analog-digital hybrid dimming driver circuit Technical Field

[0001] This utility model relates to the field of dimming drive circuits, and in particular to an LED analog-digital hybrid dimming drive circuit. Background Technology

[0002] In today's stage lighting industry, dimming is crucial. Dimming allows for adjustments to the brightness and color of lights according to different stages and atmospheres of a performance, thereby enhancing the artistic expression of the stage performance. For example, in tragic scenes, dimming can create a dark and oppressive atmosphere, while in comedic scenes, it can create bright and cheerful lighting effects. Dimming technology can highlight key characters or actions on stage, guide the audience's gaze, and strengthen dramatic conflict and emotional expression. For instance, when the main character appears, dimming can put them in focus, increasing audience attention. Dimming can create rich visual effects, such as gradations, flashes, and chasing effects, which can increase the entertainment value and interest of stage performances, providing the audience with a more immersive visual experience. In modern stage performances, dimming is often used in conjunction with stage machinery, smoke machines, bubble machines, and other equipment to create a multi-layered and evocative stage atmosphere. For example, when depicting magic or science fiction scenes, dimming can be combined with smoke machines to create mysterious and unpredictable light and shadow effects. In conclusion, dimming is crucial for stage lighting, as it not only enhances the artistic level of a performance but also strengthens the audience's immersion and participation.

[0003] Currently, dimming is mainly divided into two types: digital signal dimming and analog signal dimming. However, both of these dimming methods have their own drawbacks.

[0004] Digital dimming can generate electromagnetic interference, affecting the normal operation of other electronic devices. Compared to analog dimming or other simple dimming methods, the hardware components required for digital dimming are usually more expensive. Furthermore, the switching process involved in digital dimming can cause noise from other electronic components, such as inductors and LED light sources.

[0005] Analog dimming has a narrow dimming range and is not suitable for large-scale brightness adjustment. Moreover, since the LED driver is always in operation, and the conversion efficiency of the LED driver decreases rapidly as the output current decreases, using analog dimming will increase the power loss of the power supply system. Summary of the Invention

[0006] The purpose of this invention is to provide an LED analog-digital hybrid dimming drive circuit that can combine the advantages of digital dimming and analog dimming while ensuring dimming effect.

[0007] The LED analog-digital hybrid dimming drive circuit of this utility model includes an MCU controller and a dimming drive chip. The low-side output terminal of the dimming drive chip is electrically connected to a power switching element. The power switching element is electrically connected to the negative terminal of the LED lamp through an inductor. The PWM output terminal of the MCU controller outputs a digital signal to the PWM input terminal of the dimming drive chip. A digital-to-analog conversion integrator circuit is provided between the IO output terminal of the MCU controller and the ADJ input terminal of the dimming drive chip. The IO output terminal of the MCU controller outputs a digital signal to the digital-to-analog conversion integrator circuit, which converts the digital signal into an analog signal and sends it to the ADJ input terminal of the dimming drive chip.

[0008] The LED analog-digital hybrid dimming driver circuit of this invention uses a digital signal PWM to control the power switching element at the low-side output of the dimming driver chip to adjust the brightness of the LED when the LED output is at low brightness. When the LED output is at high brightness, the MCU controller outputs a digital signal to the digital-to-analog converter integrator circuit to convert it into an analog signal, which then controls the power switching element at the low-side output of the dimming driver chip to adjust the brightness of the LED. This combines the advantages of both digital and analog dimming while ensuring dimming performance. It avoids the noise problem caused by switching in single digital signal dimming and the power consumption problem caused by the LED driver circuit constantly working in single analog signal dimming. This makes the stage lighting quieter and suitable for special applications. Furthermore, this LED analog-digital hybrid dimming driver circuit allows the LED to switch from on to off more quickly, facilitating the application of stage lighting in special scenarios. In addition, this LED analog-digital hybrid dimming driver circuit can reduce voltage and current fluctuations in the circuit, thereby reducing electromagnetic interference and improving the electromagnetic compatibility of the system.

[0009] In a preferred embodiment of this utility model, the power switching element is an N-type power MOSFET. The gate of the N-type power MOSFET is electrically connected to the low-side output terminal of the dimming driver chip, the source is grounded, the drain is connected to one end of an inductor, and the other end of the inductor is electrically connected to the negative terminal of the LED.

[0010] As a preferred embodiment of this utility model, the drain terminal of the N-type power MOSFET is provided with a first diode and a second diode, the first diode and the second diode are connected in parallel, the anodes of the first diode and the second diode are electrically connected to the drain of the N-type power MOSFET, and the cathodes are electrically connected to the DC power supply.

[0011] As a preferred embodiment of this utility model, a current-limiting resistor is provided between the gate of the N-type power MOSFET and the low-side output terminal of the dimming driver chip. One end of the current-limiting resistor is electrically connected to the gate of the N-type power MOSFET, and the other end is electrically connected to the low-side output terminal of the dimming driver chip.

[0012] As a preferred embodiment of this utility model, a filter circuit is provided between the PWM output terminal of the MCU controller and the PWM input terminal of the dimming driver chip. One end of the filter circuit is electrically connected to the PWM output terminal of the MCU controller, and the other end is electrically connected to the PWM input terminal of the dimming driver chip.

[0013] As a preferred embodiment of this utility model, the filter circuit includes a filter resistor and a filter capacitor. One end of the filter resistor is electrically connected to the PWM output terminal of the MCU controller, and the other end is electrically connected to the filter capacitor and the PWM input terminal of the dimming driver chip. The other end of the filter capacitor is grounded.

[0014] As a preferred embodiment of this utility model, a pull-down resistor is provided between the filter capacitor and the PWM input terminal of the dimming driver chip. One end of the pull-down resistor is electrically connected to the PWM input terminal of the dimming driver chip, and the other end is grounded.

[0015] As a preferred embodiment of this utility model, the digital-to-analog conversion integrating circuit includes an integrating resistor and an integrating capacitor. One end of the integrating resistor is electrically connected to the IO output terminal of the MCU controller, and the other end is electrically connected to the integrating capacitor and the ADJ input terminal of the dimming driver chip. The other end of the integrating capacitor is grounded.

[0016] As a preferred embodiment of this utility model, a P-type power MOSFET is provided between the PDRV terminal of the dimming driver chip and the positive terminal of the LED lamp. The gate of the P-type power MOSFET is electrically connected to the PDRV terminal of the dimming driver chip, the source is electrically connected to the SNSL terminal of the dimming driver chip, and the drain is electrically connected to the positive terminal of the LED lamp.

[0017] As a preferred embodiment of this utility model, a first resistor, a second resistor, and a third resistor are provided at the SNSL terminal of the dimming driver chip. The first resistor, the second resistor, and the third resistor are connected in parallel. One end of the parallel connection of the first resistor, the second resistor, and the third resistor is electrically connected to a DC power supply, and the other end is electrically connected to the SNSL terminal of the dimming driver chip. Attached Figure Description

[0018] Figure 1 is a schematic diagram of the LED analog-digital hybrid dimming drive circuit of this utility model;

[0019] Figure 2 is a circuit diagram of the LED analog-digital hybrid dimming drive circuit of this utility model. Detailed Implementation

[0020] The technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] This embodiment provides an LED analog-digital hybrid dimming drive circuit, as shown in Figure 1. It includes an MCU controller and a dimming drive chip. The low-side output terminal of the dimming drive chip is electrically connected to a power switching element. The power switching element is electrically connected to the negative terminal of the LED lamp through an inductor. The PWM output terminal of the MCU controller outputs a digital signal to the PWM input terminal of the dimming drive chip. A digital-to-analog conversion integrator circuit is provided between the IO output terminal of the MCU controller and the ADJ input terminal of the dimming drive chip. The IO output terminal of the MCU controller outputs a digital signal to the digital-to-analog conversion integrator circuit, which converts the digital signal into an analog signal and sends it to the ADJ input terminal of the dimming drive chip.

[0022] As shown in Figure 2, the MCU controller uses an STM32F103C8T6 microcontroller, and the power switching element is an N-type power MOSFET Q18, model HGN120N10AL. The gate of the N-type power MOSFET is electrically connected to the low-side output terminal of the dimming driver chip U1, the source is grounded, and the drain is connected to one end of an inductor L18. The other end of the inductor L18 is electrically connected to the negative terminal of the LED. The inductor L18 is 47uH. At startup, the MCU controller's PWM output signal is below 0.5V, and the dimming driver chip U1 turns off the low-side N-type power MOSFET Q18. The LED analog-digital hybrid dimming driver circuit has no output, and the LED is off. After the MCU controller's PWM output signal exceeds 0.5V, the dimming driver chip U1 operates normally and adjusts the LED output current according to the digital and analog signals. After the dimming driver chip U1 is working normally, the digital signal at the PWM output terminal of the MCU controller is 0-0.5V, and the LED output is at a low brightness. The digital signal PWM is used to control the power switching element at the low-side output terminal of the dimming driver chip to adjust the brightness of the LED. When the digital signal at the PWM output terminal of the MCU controller is 0.5-3V, the LED output is at a high brightness. The digital signal is output from the IO output terminal of the MCU controller to the digital-to-analog converter integrator circuit to be converted into an analog signal, which controls the power switching element at the low-side output terminal of the dimming driver chip to adjust the brightness of the LED. In this way, the advantages of digital dimming and analog dimming can be combined while ensuring the dimming effect. It can avoid the noise problem caused by switching when using a single digital signal dimming, and also avoid the power consumption problem caused by the LED driver circuit working continuously when using a single analog signal dimming. This makes the stage lighting equipment work more quietly and is suitable for some special occasions.

[0023] A filter circuit is installed between the PWM output of the MCU controller and the PWM input of the dimming driver chip. One end of the filter circuit is electrically connected to the PWM output of the MCU controller, and the other end is electrically connected to the PWM input of the dimming driver chip. The filter circuit includes a filter resistor R26 and a filter capacitor C76. One end of the filter resistor is electrically connected to the PWM output of the MCU controller, and the other end is electrically connected to both the filter capacitor and the PWM input of the dimming driver chip. The other end of the filter capacitor is grounded. The filter resistor R26 and the filter capacitor C76 effectively suppress noise at the PWM output of the MCU controller. Additionally, a pull-down resistor R62 is installed between the filter capacitor and the PWM input of the dimming driver chip. One end of the pull-down resistor is electrically connected to the PWM input of the dimming driver chip, and the other end is grounded. The combination of the filter resistor R26, the filter capacitor C76, and the pull-down resistor R62 not only stabilizes the state of the PWM output of the MCU controller but also prevents interference such as all LEDs lighting up or flickering upon power-up.

[0024] The digital-to-analog converter (DAC) integrator circuit includes an integrating resistor R69 and an integrating capacitor C74. One end of the integrating resistor is electrically connected to the I / O output of the MCU controller, and the other end is electrically connected to the integrating capacitor and the ADJ input of the dimming driver chip. The other end of the integrating capacitor is grounded. The DAC integrator circuit, composed of the integrating resistor R69 and the integrating capacitor C74, converts the digital signal output from the I / O output of the MCU controller into an analog voltage, which is then supplied to the ADJ input of the dimming driver chip.

[0025] The drain terminal of the N-type power MOSFET is equipped with a first diode D6 and a second diode D9, which are connected in parallel. The anodes of the first and second diodes are electrically connected to the drain of the N-type power MOSFET, and the cathodes are electrically connected to the DC power supply VDD. Additionally, a current-limiting resistor R25 is provided between the gate of the N-type power MOSFET and the low-side output terminal of the dimming driver chip. One end of the current-limiting resistor is electrically connected to the gate of the N-type power MOSFET, and the other end is electrically connected to the low-side output terminal of the dimming driver chip. Furthermore, a resistor R1 is connected to the drain terminal of the N-type power MOSFET. One end of resistor R1 is electrically connected to the drain terminal of the N-type power MOSFET, and the other end is connected to one end of capacitor C75, with the other end of capacitor C75 grounded. The negative terminal of the LED is also connected to a diode D4. The cathode of diode D4 is electrically connected to the negative terminal of the LED, and the anode is grounded.

[0026] A P-type power MOSFET Q17 is provided between the PDRV terminal of the dimming driver chip and the positive terminal of the LED. The P-type power MOSFET Q17 is an AP50P10NF P-type power MOSFET. The gate of the P-type power MOSFET is electrically connected to the PDRV terminal of the dimming driver chip, the source is electrically connected to the SNSL terminal of the dimming driver chip, and the drain is electrically connected to the positive terminal of the LED.

[0027] After the dimming driver chip U1 is working normally, when the digital signal at the PWM output of the MCU controller is below 0.5V, the P-type power MOSFET Q17 is off, and the electrical energy in the LED analog-digital hybrid dimming driver circuit will discharge rapidly through the inductor L18. When the digital signal at the PWM output of the MCU controller is above 0.5V, the P-type power MOSFET Q17 is on, and the voltage across the inductor L18 is close to the input voltage VDD, making the discharge much faster than traditional driver circuits, especially at high dimming frequencies. Faster discharge means that the LED can turn from on to off more quickly, which is crucial for applications requiring rapid response. In dimming applications, faster discharge speeds allow for finer brightness adjustment, especially during dimming, where rapid discharge helps reduce flicker and improve the smoothness and stability of dimming. Furthermore, rapid discharge reduces the energy consumption of the LED in its non-operating state, thereby improving the overall system energy efficiency. It also helps reduce charge accumulation in the circuit, thus reducing the risk of overvoltage and overcurrent, and improving the stability and reliability of the circuit. Rapid discharge can also reduce voltage and current fluctuations in the circuit, thereby reducing electromagnetic interference and improving the electromagnetic compatibility (EMC) of the system.

[0028] Furthermore, the LED analog-digital hybrid dimming driver circuit improves upon output waveform oscillation and overshoot, resulting in a cleaner and more stable output waveform, which is highly beneficial for applications requiring high-precision control. Moreover, the combination of the P-type power MOSFET Q17 and the LED analog-digital hybrid dimming driver circuit enables stepless brightness variation, resulting in a more natural and smooth dimming effect than traditional dimming driver circuits, thus enhancing the viewing experience. Additionally, the dimming driver chip's SNSL terminal includes a first resistor RS1, a second resistor RS2, and a third resistor RS3, connected in parallel. One end of this parallel connection is electrically connected to the DC power supply VDD, and the other end is electrically connected to the SNSL terminal of the dimming driver chip.

[0029] The above embodiments are only used to illustrate the detailed solution of this utility model. This utility model is not limited to the above detailed solution, that is, it does not mean that this utility model must rely on the above detailed solution to be implemented. Those skilled in the art should understand that any improvement to this utility model, equivalent substitution of the raw materials of this utility model product, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this utility model.

Claims

1. An LED analog-digital hybrid dimming drive circuit, comprising an MCU controller and a dimming drive chip, wherein a power switching element is electrically connected to the low-side output terminal of the dimming drive chip, and the power switching element is electrically connected to the negative terminal of the LED lamp through an inductor, characterized in that, The PWM output terminal of the MCU controller outputs a digital signal to the PWM input terminal of the dimming driver chip. A digital-to-analog converter integration circuit is set between the IO output terminal of the MCU controller and the ADJ input terminal of the dimming driver chip. The IO output terminal of the MCU controller outputs a digital signal to the digital-to-analog converter integration circuit, which converts the digital signal into an analog signal and sends it to the ADJ input terminal of the dimming driver chip.

2. The LED analog-digital hybrid dimming drive circuit according to claim 1, characterized in that, The power switching element is an N-type power MOSFET (Q18). The gate of the N-type power MOSFET is electrically connected to the low-side output terminal of the dimming driver chip (U1), the source is grounded, and the drain is connected to one end of an inductor. The other end of the inductor (L18) is electrically connected to the negative terminal of the LED.

3. The LED analog-digital hybrid dimming drive circuit according to claim 2, characterized in that, The drain terminal of the N-type power MOSFET is provided with a first diode (D6) and a second diode (D9). The first diode and the second diode are connected in parallel. The anodes of the first diode and the second diode are electrically connected to the drain of the N-type power MOSFET, and the cathodes are electrically connected to the DC power supply.

4. The LED analog-digital hybrid dimming drive circuit according to claim 2, characterized in that, A current-limiting resistor (R25) is provided between the gate of the N-type power MOSFET and the low-side output terminal of the dimming driver chip. One end of the current-limiting resistor is electrically connected to the gate of the N-type power MOSFET, and the other end is electrically connected to the low-side output terminal of the dimming driver chip.

5. The LED analog-digital hybrid dimming drive circuit according to claim 1, characterized in that, A filter circuit is provided between the PWM output terminal of the MCU controller and the PWM input terminal of the dimming driver chip. One end of the filter circuit is electrically connected to the PWM output terminal of the MCU controller, and the other end is electrically connected to the PWM input terminal of the dimming driver chip.

6. The LED analog-digital hybrid dimming drive circuit according to claim 5, characterized in that, The filtering circuit includes a filter resistor (R26) and a filter capacitor (C76). One end of the filter resistor is electrically connected to the PWM output terminal of the MCU controller, and the other end is electrically connected to the filter capacitor and the PWM input terminal of the dimming driver chip. The other end of the filter capacitor is grounded.

7. The LED analog-digital hybrid dimming drive circuit according to claim 6, characterized in that, A pull-down resistor (R62) is provided between the filter capacitor and the PWM input terminal of the dimming driver chip. One end of the pull-down resistor is electrically connected to the PWM input terminal of the dimming driver chip, and the other end is grounded.

8. The LED analog-digital hybrid dimming drive circuit according to claim 1, characterized in that, The digital-to-analog conversion integrating circuit includes an integrating resistor (R69) and an integrating capacitor (C74). One end of the integrating resistor is electrically connected to the IO output terminal of the MCU controller, and the other end is electrically connected to the integrating capacitor and the ADJ input terminal of the dimming driver chip. The other end of the integrating capacitor is grounded.

9. The LED analog-digital hybrid dimming driving circuit according to claim 1, wherein, A P-type power MOSFET (Q17) is provided between the PDRV terminal of the dimming driver chip and the positive terminal of the LED. The gate of the P-type power MOSFET is electrically connected to the PDRV terminal of the dimming driver chip, the source is electrically connected to the SNSL terminal of the dimming driver chip, and the drain is electrically connected to the positive terminal of the LED.

10. The LED analog-digital hybrid dimming drive circuit according to claim 9, characterized in that, The SNSL terminal of the dimming driver chip is provided with a first resistor (RS1), a second resistor (RS2), and a third resistor (RS3). The first resistor, the second resistor, and the third resistor are connected in parallel. One end of the parallel connection of the first resistor, the second resistor, and the third resistor is electrically connected to the DC power supply, and the other end is electrically connected to the SNSL terminal of the dimming driver chip.

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