PWM (Pulse Width Modulation) absorption circuit

Abstract

The utility model relates to the technical field of light control, in particular to a PWM (Pulse Width Modulation) absorption circuit, which comprises an MCU (Microprogrammed Control Unit), an AC-DC (Alternating Current-Direct Current) module, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a first MOS (Metal Oxide Semiconductor) tube Q1, a second MOS tube Q2, a third MOS tube Q3, a first capacitor C1 and a diode D1, the output is provided with the resistor R1, the first MOS tube Q1 is controlled to be switched on, when the PWM outputs high level, an LED (Light Emitting Diode) lamp is turned on, and the MOS tube Q1 is controlled to switch off the resistor; when the PWM outputs a low level, energy stored in an inductor and a capacitor of an LED line is absorbed by controlling conduction of a resistor, the energy stored in the inductor and the capacitor of the LED line is absorbed by the resistor, and an LED lamp is not turned on, so that consistency of multiple loads is ensured, and abnormal conditions are avoided; according to the PWM absorption circuit of the utility model, when the PWM drive turns off the Q2, the current is suddenly turned off, and the energy stored by the inductor and the capacitor existing in the LED circuit cannot be immediately discharged, and when the PWM output is turned off, the energy stored by the inductor and the capacitor existing in the LED circuit is absorbed, thereby avoiding the instability of the LED lamp circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of LED lighting control, in particular to a PWM absorption circuit. Background Art

[0002] In a PWM dimming absorption circuit, when the PWM output is low, the LED light board or light strip connected to the output also has a low voltage. However, since the output is lower than the LED lamp voltage, it does not conduct, and some electrical energy still remains in the circuit. In addition, the LED lamp is not stable during the dimming process, especially when dimming to the darkest level, and flickering may occur.

[0003] Existing PWM dimming drivers are not compatible with LEDs with constant current drive. When driving different LED lamp voltages simultaneously, there is no absorption circuit. When dimming to a lower brightness, the actual brightness of the LED lamp will be higher than the set brightness due to the presence of capacitors or inductors in the LED light strip or lamp cup, and sometimes the output luminosity will be unstable.

[0004] In view of the above problems, it is necessary to improve the PWM absorption circuit of LED to solve the above problems. Utility Model Content

[0005] The purpose of the utility model is to provide a PWM absorption circuit to solve the technical problem of unstable brightness of existing LED lamps.

[0006] The utility model provides a PWM absorption circuit, including an MCU, an AC-DC module, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, a first capacitor C1 and a diode D1.

[0007] One end of the MCU is connected to the AC-DC module, and the other end is connected between the second MOS transistor Q2 and the third MOS transistor Q3. The positive end of the AC-DC module is connected to one end of the diode D1 and one end of the resistor R1. The negative end of the AC-DC module is connected to the first capacitor C1, the third MOS transistor Q3, and the second MOS transistor Q2. One end of the diode D1 is connected in series with the second resistor R2. One end of the first capacitor C1 is connected between the diode D1 and the second resistor R2, and the other end is connected to the negative end of the AC-DC module. One pin of the first MOS transistor Q1 is connected to the resistor R1, another pin is connected to the resistor R2, and another pin is connected to the resistor R3. One pin of the third MOS transistor Q3 is connected to the resistor R2, another pin is connected to the second MOS transistor Q2, and another pin is connected to the negative end of the AC-DC module. Resistors R4 and R5 are also connected between the second MOS transistor Q2 and the third MOS transistor Q3.

[0008] Preferably, the resistor R1 is connected in series with the first MOS transistor Q1 and is connected to the output end.

[0009] Compared with the prior art, the beneficial effects of the present invention are:

[0010] This utility model provides a PWM absorption circuit. When the PWM drive turns off the second MOS transistor Q2, the current suddenly shuts off, and the energy stored in the inductor and capacitor in the LED circuit cannot be immediately discharged. However, when this circuit is connected and the PWM output is turned off, it absorbs the energy stored in the inductor and capacitor in the LED circuit, preventing instability in the LED circuit and effectively improving product stability without flickering. This circuit is simple and effective, with no impact on the original circuit, a simple circuit, and low loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0012] Figure 1 This is a schematic diagram of a PWM absorption circuit of the utility model;

[0013] Figure 2 This is a voltage diagram of the LED lamp without absorption circuit of the utility model;

[0014] Figure 3 This is a schematic diagram of the LED lamp voltage after adding PWM absorption in the utility model. DETAILED DESCRIPTION

[0015] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0016] like Figure 1As shown, a PWM absorption circuit of the present invention includes an MCU, an AC-DC module, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, a first capacitor C1 and a diode D1. One end of the MCU is connected to the AC-DC module, and the other end is connected between the second MOS transistor Q2 and the third MOS transistor Q3. The positive end of the AC-DC module is connected to one end of the diode D1 and one end of the resistor R1. The negative end of the AC-DC module is connected to the first capacitor C1, the third MOS transistor Q2 and the third MOS transistor Q3. One end of the diode D1 is connected in series with the second resistor R2, and one end of the first capacitor C1 is connected between the diode D1 and the second resistor R2. The other end of the first capacitor C1 is connected to the negative terminal of the AC-DC module. One pin of the first MOS transistor Q1 is connected to the resistor R1, the other pin is connected to the resistor R2, and the other pin is connected to the resistor R3. One pin of the third MOS transistor Q3 is connected to the resistor R2, the other pin is connected to the second MOS transistor Q2, and the other pin is connected to the negative terminal of the AC-DC module. Resistors R4 and R5 are also connected between the second MOS transistor Q2 and the third MOS transistor Q3. Resistor R1 is connected in series with the first MOS transistor Q1 and is connected to the output terminal.

[0017] This utility model is a PWM absorption circuit, which sets the output resistor and controls the conduction of the MOS tube. When the PWM output is high, the LED light is on, and the first MOS tube Q1 is controlled to turn off the resistor; when the PWM output is low, the resistor R1 is controlled to conduct, absorbing the energy stored in the inductor and capacitor of the LED circuit. The energy stored in the inductor and capacitor of the LED circuit is absorbed by the resistor R1, and the LED light is not on, thereby ensuring the consistency of multiple loads and avoiding abnormal situations. For judgment of whether there is absorption, refer to Figure 2 and Figure 3 .

[0018] The operating principle of a PWM absorption circuit of the utility model is as follows: a low-resistance resistor R1 is connected in series with a first MOS transistor Q1 and connected in parallel at the output end. Resistor R1 is controlled by the first MOS transistor Q1. When the PWM output is high, the second MOS transistor Q2 is turned on, and the LED lights up. Simultaneously, diode D1 charges the first capacitor C1. The G pin of the third MOS transistor Q3 is simultaneously connected to the PWM signal. When the G pin is high, the third MOS transistor Q3 is turned on. The turning on of the third MOS transistor Q3 pulls the G pin of the first MOS transistor Q1 to a low level, turning off the first MOS transistor Q1 and deactivating resistor R1. When the PWM output is low, the second MOS transistor Q2 is turned off. The G pin of the third MOS transistor Q3 is simultaneously connected to the PWM signal. When the G pin of the third MOS transistor Q3 is low, the third MOS transistor Q3 is turned off. The energy stored in the first capacitor C1 is pulled high by resistor R2, turning on the first MOS transistor Q1. The first MOS transistor Q1 is connected in series with resistor R1 to form a loop in parallel with the LED end, absorbing the energy stored in the inductor and capacitor of the LED circuit, and the LED lights off.

[0019] In addition, when the PWM drive turns off the second MOS transistor Q2, the current is suddenly cut off, and the energy stored in the inductor and capacitor in the LED circuit cannot be discharged immediately. However, when this circuit is connected, when the PWM output is turned off, the energy stored in the inductor and capacitor in the LED circuit is absorbed, thus preventing instability in the LED lamp circuit.

[0020] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A PWM absorption circuit, characterized in that: It includes MCU, AC-DC module, resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, first MOS transistor Q1, second MOS transistor Q2, third MOS transistor Q3, first capacitor C1 and diode D1. One end of the MCU is connected to the AC-DC module, and the other end is connected between the second MOS transistor Q2 and the third MOS transistor Q3. The positive end of the AC-DC module is connected to one end of the diode D1 and one end of the resistor R1. The negative end of the AC-DC module is connected to the first capacitor C1, the third MOS transistor Q3, and the second MOS transistor Q2. One end of the diode D1 is connected in series with the second resistor R2. One end of the first capacitor C1 is connected between the diode D1 and the second resistor R2, and the other end is connected to the negative end of the AC-DC module. One pin of the first MOS transistor Q1 is connected to the resistor R1, another pin is connected to the resistor R2, and another pin is connected to the resistor R3. One pin of the third MOS transistor Q3 is connected to the resistor R2, another pin is connected to the second MOS transistor Q2, and another pin is connected to the negative end of the AC-DC module. Resistors R4 and R5 are also connected between the second MOS transistor Q2 and the third MOS transistor Q3.

2. The PWM absorption circuit according to claim 1, wherein: The resistor R1 is connected in series with the first MOS transistor Q1 and is connected to the output end.

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