High-frequency dimming drive circuit and lamp

Abstract

The utility model discloses a high-frequency dimming drive circuit and a lamp, the drive circuit is connected with a light-emitting assembly, and the drive circuit comprises an optocoupler and a first MOS tube; a first pin of the optocoupler is connected with a PWM signal input end, a second pin of the optocoupler is grounded, a fourth pin of the optocoupler is connected with a power supply end, and a third pin of the optocoupler is grounded; the grid electrode of the first MOS tube is connected with the power supply end and the fourth pin of the optocoupler, the drain electrode of the first MOS tube is connected with the power supply end and the drain electrode of the first MOS tube, and the source electrode of the first MOS tube is grounded; the grid electrode of the second MOS tube is connected with the power supply end, the PWM signal output end is simultaneously connected to the grid electrode of the second MOS tube and the power supply end, the drain electrode of the second MOS tube is connected with the negative electrode of the light-emitting device, and the source electrode of the second MOS tube is grounded. The voltage waveform of the PWM output signal is not prone to distortion, the problems that the dimming range of high-frequency driving is narrow and the lamp flickers when the duty ratio is low are solved, and the user experience feeling is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, and in particular to a high-frequency dimming drive circuit and a lamp. Background Art

[0002] PWM (pulse width modulation) technology is widely used in the field of LED brightness adjustment. The current isolated dimming / color adjustment drive circuit uses optocouplers to achieve signal transmission and electrical isolation.

[0003] However, if Figure 5 As shown, the current driving circuit can be used normally when driving at a low frequency (driving frequency 1-3KHZ). However, when driving at a high frequency (driving frequency 4-10KHZ) or adjusting the brightness at a low level (low duty cycle), the response speed is slow due to the delay in the optocoupler's response to the rising and falling levels of the PWM input signal. The PWM output end is directly connected in series with the output end of the optocoupler's phototransistor, causing the voltage waveform of the PWM output signal to be distorted, which can easily lead to the following problems: the dimming range becomes narrower. Under normal circumstances, the adjustment range is 0.5%-100%, but at this time the range is only 5%-95%; the waveform distortion causes the dimming flicker problem. Utility Model Content

[0004] In order to solve the problems in the prior art, the utility model provides an improved high-frequency dimming drive circuit.

[0005] In a first aspect, the utility model discloses a high-frequency dimming driving circuit connected to a light-emitting component, wherein the high-frequency dimming driving circuit includes an optocoupler and a first MOS tube; the light-emitting component includes a light-emitting device and a second MOS tube.

[0006] The first pin of the optocoupler is connected to the PWM signal input terminal, the second pin of the optocoupler is grounded, the fourth pin of the optocoupler is connected to the power supply terminal, and the third pin of the optocoupler is grounded;

[0007] The gate of the first MOS transistor is connected to the power supply terminal and the fourth pin of the optocoupler, the drain of the first MOS transistor is connected to the power supply terminal and the drain of the first MOS transistor, and the source of the first MOS transistor is grounded;

[0008] The gate of the second MOS tube is connected to the power supply end, the PWM signal output end is connected to the gate of the second MOS tube and the power supply end at the same time, the drain of the second MOS tube is connected to the cathode of the light emitting device, and the source of the second MOS tube is grounded.

[0009] In some embodiments, the high-frequency dimming driving circuit further includes a fifth resistor (R18); a first end of the fifth resistor is connected to the power supply end, a second end of the fifth resistor is connected to the gate of the second MOS tube and the drain of the first MOS tube, and a PWM signal output end is simultaneously connected to the gate of the second MOS tube and the second end of the fifth resistor.

[0010] In some embodiments, the high-frequency dimming driving circuit further includes a fourth resistor; a first end of the fourth resistor is connected to a power supply end, and a second end of the fourth resistor is connected to the fourth pin of the optocoupler and the gate of the first MOS tube.

[0011] In some embodiments, the high-frequency dimming driving circuit further includes a third resistor; a first end of the third resistor is connected to the second end of the fourth resistor and the fourth pin of the optocoupler, and a second end of the third resistor is connected to the gate of the first MOS tube.

[0012] In some embodiments, the high-frequency dimming driving circuit also includes a first diode; the first diode is connected in parallel with the third resistor, the positive electrode of the diode is connected to the gate of the first MOS tube, and the negative electrode of the first diode is connected to the fourth pin of the optocoupler.

[0013] In some embodiments, the light-emitting component further includes a second resistor, and the second resistor is connected in parallel with the gate and source of the second MOS transistor.

[0014] In some embodiments, the high-frequency dimming driving circuit further includes a first resistor, one end of the first resistor is connected to the second pin of the optocoupler, and the other end of the first resistor is grounded.

[0015] In some embodiments, the high-frequency dimming driving circuit further includes a first capacitor, one end of the first capacitor is connected to the power supply end, and the other end of the capacitor is grounded.

[0016] In some embodiments, the optocoupler is a five-pin optocoupler, and the fifth pin of the five-pin optocoupler is connected to the power supply terminal and one end of the first capacitor.

[0017] In a second aspect, the utility model discloses a lamp, comprising the high-frequency dimming drive circuit and a light-emitting component as described in the first aspect, wherein the high-frequency dimming drive circuit is connected to the light-emitting component.

[0018] Beneficial effects of the present invention: The present invention discloses a high-frequency dimming drive circuit and a lamp, wherein the high-frequency dimming drive circuit is connected to a light-emitting component, the high-frequency dimming drive circuit includes an optocoupler and a first MOS tube; the light-emitting component includes a light-emitting device and a second MOS tube; the first pin of the optocoupler is connected to a PWM signal input terminal, the second pin of the optocoupler is grounded, the fourth pin of the optocoupler is connected to a power supply terminal, and the third pin of the optocoupler is grounded; the gate of the first MOS tube is connected to the power supply terminal and the fourth pin of the optocoupler, the drain of the first MOS tube is connected to the power supply terminal and the drain of the first MOS tube, and the source of the first MOS tube is grounded; the gate of the second MOS tube is connected to the power supply terminal, the PWM signal output terminal is connected between the gate of the second MOS tube and the power supply terminal, the drain of the second MOS tube is connected to the negative electrode of the light-emitting device, and the source of the second MOS tube is grounded. In the above-mentioned high-frequency dimming drive circuit, the PWM output end is connected to the power supply end. The level of the PWM output end is directly affected by the on-off of the first MOS tube. Since the first MOS tube is a voltage-type device, it responds more quickly to changes in high and low levels. The voltage waveform of the PWM output signal is not easily distorted, thereby solving the problem of narrow dimming range of high-frequency drive and flickering of lamps at low duty cycle, thereby improving user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a diagram showing the overall circuit structure of the high-frequency dimming drive circuit and the light-emitting component provided in an embodiment of the present utility model;

[0021] Figure 2 This is a PWM signal waveform diagram of points A, B, and C in the high-frequency dimming drive circuit provided by an embodiment of the utility model;

[0022] Figure 3 This is an overall circuit structure diagram of a high-frequency dimming drive circuit and a light-emitting component provided in another embodiment of the present invention;

[0023] Figure 4 A schematic diagram of the overall circuit structure of a lamp provided by an embodiment of the utility model;

[0024] Figure 5 The overall circuit structure diagram of the dimming drive circuit of the background technology.

[0025] Figure Number:

[0026] U1, optocoupler; Q1, first MOS tube; Q2, second MOS tube; R1, first resistor; R2, second resistor; R7, third resistor; R8, fourth resistor; R18, fifth resistor; D1, first diode; VCC, power supply terminal; C1, first capacitor. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] It will be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0029] It should also be noted that, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected", "fixed", and "set" should be understood in a broad sense. For example, they can be fixedly connected, detachably connected, or integrated; they can be mechanically connected or electrically connected; they can be directly connected or indirectly connected through an intermediate medium, and they can be internal connections between two elements or interactions between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intervening elements. The terms "first", "second", and "third" are only used to facilitate the description of the present technical solution and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", and "third" can explicitly or implicitly include one or more of these features. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] It should also be understood that the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0031] It should be further understood that the terms “and” and “or” used in the present specification and the appended claims refer to any and all possible combinations of one or more of the associated listed items, and include these combinations.

[0032] like Figure 1 As shown, an embodiment of the present utility model discloses a high-frequency dimming drive circuit connected to a light-emitting component, wherein the drive circuit includes an optocoupler U1 and a first MOS transistor Q1; the light-emitting component includes a light-emitting device and a second MOS transistor Q2; the first pin of the optocoupler U1 is connected to a PWM signal input terminal, the second pin of the optocoupler U1 is grounded, the fourth pin of the optocoupler U1 is connected to a power supply terminal VCC, and the third pin of the optocoupler U1 is grounded; the gate of the first MOS transistor Q1 is connected to the power supply terminal VCC and the fourth pin of the optocoupler U1, the drain of the first MOS transistor Q1 is connected to the power supply terminal VCC, and the source of the first MOS transistor Q1 is grounded; the gate of the second MOS transistor Q2 is connected to the power supply terminal VCC and the drain of the first MOS transistor Q1, the PWM signal output terminal is connected to the gate of the second MOS transistor Q2 and the power supply terminal VCC, the drain of the second MOS transistor Q2 is connected to the cathode of the light-emitting device, and the source of the second MOS transistor Q2 is grounded.

[0033] Optocoupler U1 is a four-pin optocoupler. Pin 1 is the positive electrode of the light-emitting diode (LED), pin 2 is the negative electrode of the LED, pin 4 is the collector of the phototransistor (PTD), and pin 3 is the emitter of the phototransistor. The PWM signal input accepts high- and low-level conversions between high and low levels. The high level can be 5V, and the low level can be 0V or near 0V. When the PWM signal input is high (i.e., point A is high), the voltage of the optocoupler U1's LED reaches its threshold and emits light, converting the electrical signal into an optical signal. The phototransistor of optocoupler U1 receives the light signal from the light-emitting diode, and the circuit in which the phototransistor resides conducts, generating current, thereby converting the light signal into an electrical signal. When the photocoupler conducts, the third pin of optocoupler U1 is grounded, causing point B to be at a low level. As a result, the voltage waveform at point B is opposite to that at point A. The gate connected to power supply terminal VCC and the fourth pin of optocoupler U1 is also at a low level, turning off first MOS transistor Q1. With first MOS transistor Q1 turned off, the gate of second MOS transistor Q2, connected to power supply terminal VCC and the drain of first MOS transistor Q1, is at a high level, turning on second MOS transistor Q2. This, in turn, turns on the circuit of the light-emitting device connected to the drain of second MOS transistor Q2, causing the light-emitting device to emit light. The light-emitting device can be a number of light-emitting diodes connected in series or in parallel. The positive electrode of the light-emitting device is connected to the positive electrode of the power supply device. If multiple light-emitting diodes are connected in series, the positive electrode of the first light-emitting diode serves as the positive electrode of the light-emitting device, and the negative electrode of the last light-emitting diode serves as the negative electrode of the light-emitting device. If multiple light-emitting diodes are connected in parallel, the positive electrode of each light-emitting diode is connected and serves as the positive electrode of the light-emitting device, and the negative electrode of each light-emitting diode is also connected and serves as the negative electrode of the light-emitting device. The PWM signal output terminal connected between the gate of the second MOS transistor Q2 and the power supply terminal VCC can be used to detect the voltage between the power supply terminal VCC and the gate of the second MOS transistor Q2, that is, the voltage at point C. Figure 2 As shown, the PWM signal at point A is safely isolated and transmitted to point C through the optocoupler U1. The waveform at point C is the same as that at point A, avoiding signal distortion and distortion during the transmission process. This allows the high-frequency dimming drive circuit to achieve dimming function during high-frequency drive by adjusting the PWM duty cycle.

[0034] When the PWM signal input terminal is low, that is, point A is low, the voltage across the light-emitting diode (LED) of optocoupler U1 fails to reach the threshold, causing the optocoupler to turn off. Point B becomes high, and the gate connected to the power supply terminal VCC and the fourth pin of optocoupler U1 also becomes high, turning on the first MOS transistor Q1. Since the first MOS transistor Q1 is turned on, its source is grounded, causing point C and the gate of the second MOS transistor Q2, which is connected to the power supply terminal VCC and the drain of the first MOS transistor Q1, to become low, turning off the second MOS transistor Q2. This, in turn, prevents the circuit of the light-emitting component connected to the drain of the second MOS transistor Q2 from conducting, turning off the light-emitting component. In this way, the PWM signal input terminal can change the dimming range by adjusting the duty cycle of the input signal.

[0035] Compared to the PWM output end being directly connected in series with the output end of the phototransistor of the optocoupler U1, the PWM output end of the embodiment of the utility model is connected to the power supply end VCC. The level of the PWM output end is directly affected by the on-off of the first MOS transistor Q1. Since the first MOS transistor Q1 is a voltage-type device, it responds more quickly to changes in high and low levels. The voltage waveform of the PWM output signal is not easily distorted, thereby solving the problem of narrow dimming range of high-frequency drive and the problem of flickering of lamps at low duty cycles, thereby improving user experience.

[0036] In a more specific embodiment, the high-frequency dimming driving circuit further includes a fifth resistor R18; a first end of the fifth resistor R18 is connected to the power supply terminal VCC, a second end of the fifth resistor R18 is connected to the gate of the second MOS transistor Q2 and the drain of the first MOS transistor Q1, and a PWM signal output end is simultaneously connected to the gate of the second MOS transistor Q2 and the second end of the fifth resistor R18.

[0037] Furthermore, a fifth resistor R18 is provided in series with the gate of the second MOS transistor Q2. On the one hand, the fifth resistor R18 can clamp the voltage between the second end of the fifth resistor R18 and the gate of the second MOS transistor Q2 to a high level when the first MOS transistor Q1 is turned off, thereby cooperating with the power supply terminal VCC to provide a driving voltage for the gate of the second MOS transistor Q2. On the other hand, the fifth resistor R18 can also serve as a current limiter to protect the second MOS transistor Q2 and improve the stability and reliability of the circuit.

[0038] In a more specific embodiment, the high-frequency dimming driving circuit further includes a fourth resistor R8; a first end of the fourth resistor R8 is connected to the power supply terminal VCC, and a second end of the fourth resistor R8 is connected to the fourth pin of the optocoupler U1 and the gate of the first MOS transistor Q1.

[0039] Furthermore, a fourth resistor R8 is connected in series with the gate of the first MOS transistor Q1. When the optocoupler U1 is turned off, the fourth resistor R8 can clamp the voltage between the second end of the fourth resistor R8 and the gate of the first MOS transistor to a high level, thereby cooperating with the power supply terminal VCC to provide a drive voltage for the gate of the first MOS transistor Q1. Furthermore, the fourth resistor R8 can also act as a current limiter to protect the first MOS transistor Q1 and improve the stability and reliability of the circuit.

[0040] In a more specific embodiment, the high-frequency dimming driving circuit further includes a third resistor R7; a first end of the third resistor R7 is connected to the second end of the fourth resistor R8 and the fourth pin of the optocoupler U1, and a second end of the third resistor R7 is connected to the gate of the first MOS tube Q1.

[0041] Furthermore, a third resistor R7 is provided between the fourth resistor R8 and the gate of the first MOS transistor Q1. Due to the presence of parasitic capacitance in the first MOS transistor Q1, a large current will flow through the gate of the first MOS transistor Q1 at the moment when point B becomes high and the first MOS transistor Q1 is turned on. The third resistor R7 can reduce this instantaneous current value to protect the first MOS transistor Q1.

[0042] In a more specific embodiment, the high-frequency dimming drive circuit also includes a first diode D1; the first diode D1 is connected in parallel with the third resistor R7, the anode of the first diode D1 is connected to the gate of the first MOS tube Q1, and the cathode of the first diode D1 is connected to the fourth pin of the optocoupler U1.

[0043] Furthermore, a first diode D1 is connected in reverse parallel across the third resistor R7. Since the first MOS transistor Q1 has a junction capacitance, when the first MOS transistor Q1 is turned off, the first diode D1 can provide a pressure relief channel for the junction capacitance, accelerating the turn-off of the first MOS transistor Q1. This allows the high-frequency square wave pulse signal at point C to maintain a steep decline waveform, allowing the high-frequency dimming drive circuit to maintain a larger dimming range during high-frequency dimming.

[0044] In a more specific embodiment, the light emitting component further includes a second resistor R2 , and the second resistor R2 is connected in parallel with the gate and source of the second MOS transistor Q2 .

[0045] Furthermore, one end of the second resistor R2 is connected to the gate of the second MOS transistor Q2, and the other end of the second resistor R2 is connected to the source of the second MOS transistor Q2. The second resistor R2 is used to reduce the input impedance of the second MOS transistor Q2 to prevent accidental interference from causing the second MOS transistor Q2 to be connected incorrectly.

[0046] In a more specific embodiment, the high-frequency dimming driving circuit further includes a first resistor R1 , one end of the first resistor R1 is connected to the second pin of the optocoupler U1 , and the other end of the first resistor R1 is grounded.

[0047] Furthermore, a first resistor R1 is connected in series between the second pin of the optocoupler and the ground. The first resistor R1 is used to limit the current passing through the light-emitting diode of the optocoupler to ensure stable operation of the optocoupler U1 and improve the dimming reliability and stability of the driving circuit.

[0048] In a more specific embodiment, the high-frequency dimming driving circuit further includes a first capacitor C1 , one end of the first capacitor C1 is connected to the power supply terminal VCC, and the other end of the capacitor is grounded.

[0049] Furthermore, connecting a first capacitor C1 between the power supply and the ground can make the DC voltage outputted by the power supply terminal VCC smoother, and play the role of voltage smoothing and filtering. The value of the first capacitor C1 is 0.1uF.

[0050] like Figure 3 As shown, in a more specific embodiment, the optocoupler U1 is a five-pin optocoupler U1, and the fifth pin of the five-pin optocoupler U1 is connected to the power supply terminal VCC and one end of the first capacitor C1.

[0051] In this embodiment, the optocoupler U1 is a five-pin high-speed optocoupler. The fifth pin of the five-pin optocoupler U1 is connected to the power supply terminal VCC and one end of the first capacitor C1. The circuit connection relationship of the remaining four pins of the five-pin optocoupler U1 is the same as in the above embodiment. Compared to the four-pin optocoupler U1, the five-pin optocoupler U1 has a faster response speed, which enables the high-frequency dimming driver circuit to have a deeper dimming range.

[0052] See also Figure 4 The embodiment of the present utility model further discloses a lamp, wherein the lamp includes the high-frequency dimming circuit and the light-emitting component as described in the above embodiment, and the high-frequency dimming driving circuit is connected to the light-emitting component.

[0053] Specifically, the lamp may include multiple PWM signal input terminals, high-frequency dimming circuits, and light-emitting components, such as PWM 1 to PWM N, driver 1 to driver N (i.e., high-frequency driver circuits), and LED 1 to LED N (i.e., light-emitting devices in the light-emitting components).

[0054] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A high-frequency dimming drive circuit connected to a light-emitting component, characterized in that: The high-frequency dimming driving circuit includes an optocoupler and a first MOS tube; the light-emitting component includes a light-emitting device and a second MOS tube; The first pin of the optocoupler is connected to the PWM signal input terminal, the second pin of the optocoupler is grounded, the fourth pin of the optocoupler is connected to the power supply terminal, and the third pin of the optocoupler is grounded; The gate of the first MOS transistor is connected to the power supply terminal and the fourth pin of the optocoupler, the drain of the first MOS transistor is connected to the power supply terminal and the drain of the first MOS transistor, and the source of the first MOS transistor is grounded; The gate of the second MOS tube is connected to the power supply end, the PWM signal output end is connected to the gate of the second MOS tube and the power supply end at the same time, the drain of the second MOS tube is connected to the cathode of the light emitting device, and the source of the second MOS tube is grounded.

2. The high-frequency dimming driving circuit according to claim 1, characterized in that: The high-frequency dimming drive circuit also includes a fifth resistor; a first end of the fifth resistor is connected to the power supply end, a second end of the fifth resistor is connected to the gate of the second MOS tube and the drain of the first MOS tube, and a PWM signal output end is simultaneously connected to the gate of the second MOS tube and the second end of the fifth resistor.

3. The high-frequency dimming driving circuit according to claim 1, characterized in that: The high-frequency dimming driving circuit further includes a fourth resistor; a first end of the fourth resistor is connected to the power supply end, and a second end of the fourth resistor is connected to the fourth pin of the optocoupler and the gate of the first MOS tube.

4. The high-frequency dimming driving circuit according to claim 3, characterized in that: The high-frequency dimming driving circuit further includes a third resistor; a first end of the third resistor is connected to the second end of the fourth resistor and the fourth pin of the optocoupler, and a second end of the third resistor is connected to the gate of the first MOS tube.

5. The high-frequency dimming driving circuit according to claim 4, characterized in that: The high-frequency dimming driving circuit also includes a first diode; the first diode is connected in parallel with the third resistor, the anode of the diode is connected to the gate of the first MOS tube, and the cathode of the first diode is connected to the fourth pin of the optocoupler.

6. The high-frequency dimming driving circuit according to claim 1, characterized in that: The light emitting component further includes a second resistor, which is connected in parallel with the gate and source of the second MOS tube.

7. The high-frequency dimming driving circuit according to claim 1, characterized in that: The high-frequency dimming driving circuit further includes a first resistor, one end of the first resistor is connected to the second pin of the optocoupler, and the other end of the first resistor is grounded.

8. The high-frequency dimming driving circuit according to claim 1, characterized in that: The high-frequency dimming driving circuit further includes a first capacitor, one end of the first capacitor is connected to the power supply end, and the other end of the capacitor is grounded.

9. The high-frequency dimming driving circuit according to claim 8, characterized in that: The optocoupler is a five-pin optocoupler, and the fifth pin of the five-pin optocoupler is connected to the power supply end and one end of the first capacitor.

10. A lamp, characterized in that: It comprises the high-frequency dimming driving circuit and the light-emitting component according to any one of claims 1 to 9, wherein the high-frequency dimming driving circuit is connected to the light-emitting component.

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