Universal dimming circuit

Abstract

The utility model discloses a universal dimming circuit which comprises an MCU processor, a rectification circuit, a voltage stabilizing circuit, an MOS tube switching circuit, a dimming signal input circuit and a zero point detection circuit. Two alternating current input ends of the rectification circuit are used for being connected with commercial power, a positive output end of the rectification circuit is connected with a load positive connection end of the universal dimming circuit and an input end of the zero point detection circuit, a negative output end of the rectification circuit is grounded, and an output end of the zero point detection circuit is connected with the MCU processor. The input end of the MOS tube switching circuit is connected with the load negative connection end of the universal dimming circuit, the output end of the MOS tube switching circuit is grounded, the control end of the MOS tube switching circuit is connected with the MCU processor, and the dimming signal input circuit is connected with the MCU processor. The LED dimming circuit can adapt to LED loads with different powers, has no dimming noise and is stable in brightness.

Description

Technical Field

[0001] The utility model relates to the field of dimmers, in particular to a universal dimming circuit. Background Art

[0002] The dimmer of the prior art uses a thyristor circuit to change the sinusoidal waveform by adjusting the conduction angle of each half-wave of the alternating current, thereby changing the effective value of the alternating current to achieve the purpose of dimming.

[0003] However, due to the conduction characteristics of thyristors, existing dimmers require the LED load to be at a certain power level before they can turn on, making them unsuitable for low-power LED loads. Furthermore, existing dimmers require the introduction of inductors and capacitors, and inductors are prone to producing audible dimming noise, impacting the user experience.

[0004] In view of the existence of the above problems, it is necessary to study a universal dimming circuit that can be applied to LED loads of different powers and has less interference. Utility Model Content

[0005] The purpose of the utility model is to provide a universal dimming circuit, which can be applied to LED loads of different powers and has less interference.

[0006] In order to achieve the above objectives, the solution of the present invention is:

[0007] A universal dimming circuit comprises an MCU processor, a rectifier circuit, a voltage stabilizing circuit, a MOS tube switch circuit, a dimming signal input circuit, and a zero point detection circuit. The two AC input terminals of the rectifier circuit are used to access the mains, the positive output terminal of the rectifier circuit is connected to the positive connection terminal of the load of the universal dimming circuit and the input terminal of the zero point detection circuit, the negative output terminal of the rectifier circuit is grounded, the output terminal of the zero point detection circuit is connected to the MCU processor, the input terminal of the MOS tube switch circuit is connected to the negative connection terminal of the load of the universal dimming circuit, the output terminal of the MOS tube switch circuit is grounded, the control terminal of the MOS tube switch circuit is connected to the MCU processor, and the dimming signal input circuit is connected to the MCU processor.

[0008] The universal dimming circuit further comprises a voltage stabilizing circuit, the input end of the voltage stabilizing circuit is connected to the positive output end of the rectifier circuit, and the output end of the voltage stabilizing circuit outputs the control power supply VCC to the MCU processor.

[0009] The dimming signal input circuit includes a variable resistor VR1, a first fixed end of the variable resistor VR1 is connected to a control power supply VCC, a second fixed end of the variable resistor VR1 is grounded, and an active end of the variable resistor VR1 is connected to an MCU processor.

[0010] The MOS transistor switch circuit includes a MOS transistor M1, a drain of the MOS transistor M1 connected to the input end of the MOS transistor switch circuit, a source of the MOS transistor M1 connected to the output end of the MOS transistor switch circuit, and a gate of the MOS transistor M1 connected to the control end of the MOS transistor switch circuit.

[0011] The rectifier circuit includes a rectifier bridge DR1.

[0012] The zero point detection circuit includes a resistor R1, a resistor R2, a resistor R3 and a transistor Q1; the first end of the resistor R1 is connected to the input end of the zero point detection circuit, the second end of the resistor R1 and the first end of the resistor R2 are connected to the base of the transistor Q1, the second end of the resistor R2 and the emitter of the transistor Q1 are grounded, the collector of the transistor Q1 and the first end of the resistor R3 are connected to the output end of the zero point detection circuit, and the second end of the resistor R3 is connected to the control power supply VCC.

[0013] After adopting the above scheme, when the present invention is used, the two AC input terminals of the rectifier circuit are connected to the mains, and the positive and negative load connection terminals of the universal dimming circuit are connected to the positive and negative electrodes of the LED load. The working principle of the present invention is as follows: the rectifier circuit converts the mains with positive and negative half-cycles into a DC pulse voltage signal with only positive half-cycles; the MCU processor outputs a PWM signal with a corresponding duty cycle to the MOS tube switch circuit based on the dimming signal input by the dimming signal input circuit, thereby controlling the current of the LED load to achieve dimming; and the MCU processor detects the zero point (zero voltage point) of the DC pulse voltage signal through the zero point detection circuit, and accordingly controls the high-level starting point of each cycle of the PWM signal to be the same as the zero point of the DC pulse voltage signal, so that the current of the LED load is the same in each cycle of the PWM signal.

[0014] From the above, it can be seen that the universal dimming circuit of the present invention adopts a post-cutting method for dimming control, so the universal dimming circuit of the present invention can be applied to various types of LED loads and has good versatility; it should be noted that the universal dimming circuit of the present invention can be applied to halogen lamps and tungsten filament lamps; moreover, since the post-cutting method is adopted for dimming control, the universal dimming circuit of the present invention does not require the use of an inductor, so no dimming noise will be generated.

[0015] In addition, the MCU processor detects the zero point of the DC pulse voltage signal through the zero point detection circuit and controls the high-level starting point of each cycle of the PWM signal to be the same as the zero point of the DC pulse voltage signal, so that the current of the LED load is the same in each cycle of the PWM signal, ensuring the brightness stability of the LED load and improving the dimming effect.

[0016] In addition, the LED load is connected in series between the positive output terminal of the rectifier circuit and the input terminal of the MOS tube switch circuit, so that the power of the LED load can be increased from zero, that is, the power of the LED load is not limited. Therefore, the universal dimming circuit of the present invention is suitable for LED loads of different powers; moreover, the present invention adjusts the brightness of the LED load through the PWM signal and the MOS tube switch circuit, so that the brightness of the LED load depends on the duty cycle of the PWM signal, so that the present invention can achieve 0~100% brightness adjustment of the LED load, and the brightness adjustment range is large. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a circuit diagram of the utility model.

[0018] Figure 2 This is a circuit principle diagram of the zero point detection circuit of the present utility model. DETAILED DESCRIPTION

[0019] In order to further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0020] like Figure 1 and Figure 2 As shown, the utility model discloses a universal dimming circuit, which includes an MCU processor, a rectifier circuit, a voltage stabilizing circuit, a MOS tube switch circuit, a dimming signal input circuit, and a zero point detection circuit; wherein, the two AC input ends of the rectifier circuit are used to access the mains, the positive output end of the rectifier circuit is connected to the load positive connection end of the universal dimming circuit and the input end of the zero point detection circuit, the negative output end of the rectifier circuit is grounded, the output end of the zero point detection circuit is connected to the MCU processor, the input end of the MOS tube switch circuit is connected to the load negative connection end of the universal dimming circuit, the output end of the MOS tube switch circuit is grounded, the control end of the MOS tube switch circuit is connected to the MCU processor, and the dimming signal input circuit is connected to the MCU processor.

[0021] Cooperate Figure 1 As shown, when the present invention is used, the two AC input terminals of the rectifier circuit are connected to the mains, and the load positive connection terminal and the load negative connection terminal of the universal dimming circuit are connected to the positive and negative electrodes of the LED load.

[0022] The working principle of this utility model is:

[0023] The rectifier circuit converts the AC power with positive and negative half-cycles into a DC pulse voltage signal with only positive half-cycles. The MCU processor outputs a PWM signal with a corresponding duty cycle to the MOS tube switch circuit based on the dimming signal input by the dimming signal input circuit, thereby controlling the current of the LED load to achieve dimming. In addition, the MCU processor detects the zero point (zero voltage point) of the DC pulse voltage signal through the zero point detection circuit, and accordingly controls the high-level starting point of each cycle of the PWM signal to be the same as the zero point of the DC pulse voltage signal, so that the current of the LED load is the same in each cycle of the PWM signal.

[0024] As can be seen from the above, the universal dimming circuit of the present invention adopts a post-cutting method for dimming control, so the universal dimming circuit of the present invention can be applied to various types of LED loads and has good versatility; it should be noted that the universal dimming circuit of the present invention can be applied to halogen lamps and tungsten filament lamps; and, since the post-cutting method is adopted for dimming control, the universal dimming circuit of the present invention does not require the use of an inductor, and therefore does not generate dimming noise. In addition, the MCU processor detects the zero point of the DC pulse voltage signal through the zero point detection circuit and controls the high-level starting point of each cycle of the PWM signal to be the same as the zero point of the DC pulse voltage signal, so that the current of the LED load is the same in each cycle of the PWM signal, ensuring the brightness stability of the LED load and improving the dimming effect. In addition, the LED load is connected in series between the positive output terminal of the rectifier circuit and the input terminal of the MOS tube switch circuit, so that the power of the LED load can be increased from zero, that is, the power of the LED load is not limited. Therefore, the universal dimming circuit of the present invention is suitable for LED loads of different powers; moreover, the present invention adjusts the brightness of the LED load through the PWM signal and the MOS tube switch circuit, so that the brightness of the LED load depends on the duty cycle of the PWM signal, so that the present invention can achieve 0~100% brightness adjustment of the LED load, and the brightness adjustment range is large.

[0025] In an embodiment of the present invention, the dimming signal input circuit includes a variable resistor VR1. A first fixed terminal of the variable resistor VR1 is connected to a control power supply VCC, a second fixed terminal of the variable resistor VR1 is grounded, and a movable terminal of the variable resistor VR1 is connected to an MCU processor. By adjusting the movable terminal of the variable resistor VR1, the voltage at the IO port connected to the MCU processor and the variable resistor VR1 can be adjusted, thereby achieving a continuously variable dimming signal input.

[0026] In an embodiment of the present utility model, the MOS transistor switch circuit includes a MOS transistor M1, the drain of the MOS transistor M1 is connected to the input end of the MOS transistor switch circuit, the source of the MOS transistor M1 is connected to the output end of the MOS transistor switch circuit, and the gate of the MOS transistor M1 is connected to the control end of the MOS transistor switch circuit.

[0027] In an embodiment of the present invention, the rectifier circuit includes a rectifier bridge DR1.

[0028] In an embodiment of the present invention, the zero point detection circuit includes a resistor R1, a resistor R2, a resistor R3, and a transistor Q1; a first end of resistor R1 is connected to an input end of the zero point detection circuit, a second end of resistor R1 and a first end of resistor R2 are connected to a base of transistor Q1, a second end of resistor R2 and an emitter of transistor Q1 are grounded, a collector of transistor Q1 and a first end of resistor R3 are connected to an output end of the zero point detection circuit, and a second end of resistor R3 is connected to a control power supply VCC. When the DC pulse voltage signal is at zero point, transistor Q1 is turned off, causing the zero point detection circuit to output a high level to the MCU processor; when the DC pulse voltage signal is not at zero point, transistor Q1 is turned on, causing the zero point detection circuit to output a low level to the MCU processor.

[0029] In an embodiment of the present invention, the universal dimming circuit of the present invention also includes a voltage stabilizing circuit, the input end of the voltage stabilizing circuit is connected to the positive output end of the rectifier circuit, and the output end of the voltage stabilizing circuit outputs a control power supply VCC to the MCU processor and the first fixed end of the variable resistor VR1 to power the MCU processor and the variable resistor VR1.

[0030] The above embodiments and drawings do not limit the product form and style of the present invention. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present invention.

Claims

1. A universal dimming circuit, characterized in that: It includes MCU processor, rectifier circuit, voltage regulator circuit, MOS tube switch circuit, dimming signal input circuit, and zero point detection circuit; The two AC input terminals of the rectifier circuit are used to access the mains power. The positive output terminal of the rectifier circuit is connected to the positive connection terminal of the load of the universal dimming circuit and the input terminal of the zero point detection circuit. The negative output terminal of the rectifier circuit is grounded. The output terminal of the zero point detection circuit is connected to the MCU processor. The input terminal of the MOS tube switch circuit is connected to the negative connection terminal of the load of the universal dimming circuit. The output terminal of the MOS tube switch circuit is grounded. The control terminal of the MOS tube switch circuit is connected to the MCU processor. The dimming signal input circuit is connected to the MCU processor.

2. The universal dimming circuit according to claim 1, wherein: It also includes a voltage stabilizing circuit, the input end of the voltage stabilizing circuit is connected to the positive output end of the rectifier circuit, and the output end of the voltage stabilizing circuit outputs the control power supply VCC to the MCU processor.

3. The universal dimming circuit according to claim 1, wherein: The dimming signal input circuit includes a variable resistor VR1, a first fixed end of the variable resistor VR1 is connected to a control power supply VCC, a second fixed end of the variable resistor VR1 is grounded, and an active end of the variable resistor VR1 is connected to an MCU processor.

4. The universal dimming circuit according to claim 1, wherein: The MOS transistor switch circuit includes a MOS transistor M1, a drain of the MOS transistor M1 connected to the input end of the MOS transistor switch circuit, a source of the MOS transistor M1 connected to the output end of the MOS transistor switch circuit, and a gate of the MOS transistor M1 connected to the control end of the MOS transistor switch circuit.

5. The universal dimming circuit according to claim 1, wherein: The rectifier circuit includes a rectifier bridge DR1.

6. The universal dimming circuit according to claim 1, wherein: The zero point detection circuit includes a resistor R1, a resistor R2, a resistor R3 and a transistor Q1; A first end of the resistor R1 is connected to the input end of the zero point detection circuit, a second end of the resistor R1 and a first end of the resistor R2 are connected to the base of the transistor Q1, a second end of the resistor R2 and the emitter of the transistor Q1 are grounded, a collector of the transistor Q1 and a first end of the resistor R3 are connected to the output end of the zero point detection circuit, and a second end of the resistor R3 is connected to the control power supply VCC.

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