Three-stage dimming control circuit of LED lamp and LED lamp

Abstract

The present invention relates to the field of LED dimming circuits. The present invention discloses a three-stage dimming control circuit for an LED lamp and an LED lamp, wherein the three-stage dimming control circuit for the LED lamp includes a three-stage selection switch circuit, a driving power supply circuit, an LED light source, and two detection circuits, wherein the input end of the driving power supply circuit is connected to the output end of the three-stage selection switch circuit, the output end of the driving power supply circuit is connected to the LED light source, the input ends of the two detection circuits are respectively connected to the two live wire output ends of the three-stage selection switch circuit, the output ends of the two detection circuits are connected to the loop feedback pin of the constant current control chip of the driving power supply circuit, and the output voltages of the output ends of the two detection circuits are different. The circuit structure of the present invention is simple, small in size, and low in cost. The output current is adjusted by adjusting the voltage of the loop feedback pin of the constant current control chip to perform dimming, without occupying the CS pin of the constant current control chip, resulting in a larger circuit design space and a smoother change in the output current.

Description

Technical Field

[0001] The invention belongs to the field of LED dimming circuits, and in particular relates to a three-stage dimming control circuit for an LED lamp and an LED lamp. Background Art

[0002] The existing three-stage dimming control circuit for LED lamps uses a three-wire input, two of which are live wires and one is neutral wire. Before connecting to the three-stage dimming control circuit, there is a three-stage selector switch. Through the three-stage selector switch, you can choose to connect two wires (one live wire and one neutral wire) or three wires (two live wires and one neutral wire). The existing three-stage dimming control circuits are as follows:

[0003] The first method uses two driver power supplies and two different groups of LEDs, with each driver power supply controlling a group of LEDs. By controlling the illumination of a single group of LEDs or two groups of LEDs simultaneously, three different brightness levels of light are achieved, such as the three-stage dimming LED lamp circuit disclosed in patent CN201621161990.8. However, this method has drawbacks: it includes two driver power supplies, resulting in a large volume. Because the driver power supplies are placed within the LED lamp body, many LED lamps, such as bulbs and filament lamps, are difficult to accommodate, making assembly difficult and costly.

[0004] The second solution uses a driver power supply and a group of LEDs. Two detection circuits are used to control the different feedback resistors of the CS (current sampling) pin of the constant current control chip in the driver power supply to change the output current, thereby outputting different currents for three-stage dimming. This is shown in the patent publication: CN201310283106.2, which discloses a three-stage dimming LED lamp control circuit. Compared to the first solution, the second solution uses only one driver power supply, has a simple circuit structure, is small in size, easy to assemble, and low in cost. However, the second solution also has shortcomings: different feedback resistors of the CS pin of the constant current control chip are required to change the output current, which reduces the circuit design space and reduces the smoothness of the output current change.

[0005] The third solution is to use a driving power supply and a group of LEDs. The sampling resistors used in the two detection circuits have different resistance values. After diode rectification and sampling resistor voltage division, the current is directly output to the DIM pin of the constant current control chip. The constant current control chip outputs different currents to the LED according to the different voltages input to the DIM pin, so that the LED can obtain three different brightness lights, such as the three-stage dimming control circuit of an LED lamp disclosed in the patent publication 201821017215.4. Compared with the first solution, the third solution also uses only one driving power supply, with a simple circuit structure, small size, and easy assembly. However, the third solution also has shortcomings: a dedicated constant current control chip is required, and the constant current control chip needs to have an analog signal AD sampling port. The AD sampling cost is high, which in turn causes the constant current control chip to be expensive and leaves less room for circuit design. Summary of the Invention

[0006] The object of the present invention is to provide a three-stage dimming control circuit for an LED lamp and an LED lamp to solve the above-mentioned technical problems.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a three-stage dimming control circuit for an LED lamp, comprising a three-stage selection switch circuit, a driving power supply circuit, an LED light source and two detection circuits, the input end of the driving power supply circuit is connected to the output end of the three-stage selection switch circuit, the output end of the driving power supply circuit is connected to the LED light source, the input ends of the two detection circuits are respectively connected to the two live wire output ends of the three-stage selection switch circuit, the output ends of the two detection circuits are connected to the loop feedback pin COMP of the constant current control chip of the driving power supply circuit, the output voltages of the output ends of the two detection circuits are different, and the constant current control chip is used to control the output current according to the voltage of the loop feedback pin COMP.

[0008] Furthermore, the detection circuit includes a first voltage divider circuit, a second voltage divider circuit and an electronic switch, the input end of the first voltage divider circuit is connected to the live wire output end of the three-stage selection switch circuit, the output end of the first voltage divider detection circuit is connected to the control end of the electronic switch, the input end of the second voltage divider circuit is connected to the DC power supply, the output end of the second voltage divider circuit is connected to the loop feedback pin COMP of the constant current control chip, and the electronic switch is connected in series in the power supply circuit of the second voltage divider circuit.

[0009] Furthermore, the electronic switch is implemented using an NMOS tube.

[0010] Furthermore, the first voltage divider circuit further includes a capacitor connected between the output end of the first voltage divider circuit and the ground.

[0011] Furthermore, the first voltage-dividing circuit further includes a voltage-stabilizing diode connected between the output end of the first voltage-dividing circuit and the ground.

[0012] Furthermore, it also includes a diode D9, and the output end of the second voltage divider circuit is reversely connected in series with the diode D9 to the loop feedback pin COMP of the constant current control chip.

[0013] Furthermore, the driving power supply circuit includes a rectifier circuit and a constant current driving circuit, the input end of the rectifier circuit is connected to the output end of the three-stage selection switch circuit, the output end of the rectifier circuit is connected to the input end of the constant current driving circuit, the output end of the constant current driving circuit is connected to the LED light source, and the rectifier circuit adopts a full-wave rectifier bridge.

[0014] Furthermore, the constant current driving circuit is a BOOST boost circuit composed of a constant current control chip U2.

[0015] Furthermore, fuses are respectively connected in series to the two live wire output ends of the three-stage selection switch circuit.

[0016] The present invention also provides an LED lamp provided with the three-stage dimming control circuit of the LED lamp.

[0017] Beneficial technical effects of the present invention:

[0018] The present invention uses only one driving power supply circuit, which has a simple circuit structure, a small size, is easy to assemble, and has a low cost. The output current is adjusted to perform dimming by adjusting the voltage of the loop feedback pin COMP of the constant current control chip. The CS pin of the constant current control chip is not required, which increases the circuit design space and makes the output current change smoother. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in 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 only 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 circuit block diagram of a three-stage dimming control circuit for an LED lamp of the present invention;

[0021] Figure 2 4 is a circuit diagram of a three-stage dimming control circuit for an LED lamp according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0022] To further illustrate various embodiments, the present invention is provided with accompanying drawings. These drawings form part of the present disclosure and are primarily used to illustrate the embodiments and, in conjunction with the relevant description in the specification, to explain the operating principles of the embodiments. By referring to these drawings, one of ordinary skill in the art will understand other possible embodiments and the advantages of the present invention. The components in the figures are not drawn to scale, and similar reference numerals are generally used to represent similar components.

[0023] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, a three-stage dimming control circuit for an LED lamp includes a three-stage selection switch circuit 1, a drive power circuit, an LED light source 3 and two detection circuits 4. The drive power circuit includes a rectifier circuit 21 and a constant current drive circuit 22. The input end of the rectifier circuit 21 (i.e., the input end of the drive power circuit) is connected to the output end of the three-stage selection switch circuit 1, the output end of the rectifier circuit 21 is connected to the input end of the constant current drive circuit 22, and the output end of the constant current drive circuit 22 (the output end of the drive power circuit) is connected to the LED light source 3.

[0025] The input ends of the two-way detection circuit 4 are respectively connected to the two live wire output ends L1 and L2 of the three-stage selection switch circuit 1, and the output ends of the two-way detection circuit 4 are connected to the loop feedback pin COMP of the constant current control chip of the constant current drive circuit 22. The output voltages of the output ends of the two-way detection circuit 4 are different. The constant current control chip is used to control the size of its output current according to the voltage size of the loop feedback pin COMP to perform dimming.

[0026] The present invention uses only one driving power supply circuit, which has a simple circuit structure, a small size, is easy to assemble, and has a low cost. The output current is adjusted to perform dimming by controlling the voltage of the loop feedback pin COMP of the constant current control chip, without using the CS pin of the constant current control chip. This allows for greater circuit design space and makes the output current change smoother.

[0027] In this specific embodiment, the detection circuit 4 includes a first voltage divider circuit, a second voltage divider circuit, and an electronic switch. The input of the first voltage divider circuit is connected to the live wire output terminal L1 or L2 of the three-stage selection switch circuit 1. The output of the first voltage divider detection circuit is connected to the control terminal of the electronic switch. The input of the second voltage divider circuit is connected to a DC power supply. The output of the second voltage divider circuit is connected to the loop feedback pin COMP of the constant current control chip. The electronic switch is connected in series with the power supply circuit of the second voltage divider circuit. The use of this detection circuit 4 makes the voltage at the loop feedback pin COMP of the constant current control chip more stable, thereby making the output current more stable. However, this is not limited to this. In other embodiments, the detection circuit can also be implemented using other existing detection circuits.

[0028] Specifically, such as Figure 2 As shown, in this embodiment, the first voltage-dividing resistor of one detection circuit 4 is formed by resistors R30 and R34 connected in series, which are connected between the live output terminal L1 of the three-stage selection switch circuit 1 and ground. The first voltage-dividing resistor of the other detection circuit 4 is formed by resistors R31 and R35 connected in series, which are connected between the live output terminal L2 of the three-stage selection switch circuit 1 and ground. The use of this first voltage-dividing circuit has a simple circuit structure, is easy to implement, and has low cost, but the present invention is not limited to this. In other embodiments, the first voltage-dividing circuit can also be implemented using other existing voltage-dividing circuits.

[0029] The second voltage divider circuit of one detection circuit 4 includes resistors R29 and RS9. The resistors R29 and RS9 are connected in series at one end to a DC power supply, and at the other end to an electronic switch Q5 connected in series with ground. A resistor R32 is connected in series with the control end of the electronic switch Q5 and connected to the node between resistors R30 and R34. The node between resistors R29 and RS9 (the output end of the second voltage divider circuit) is connected to the loop feedback pin COMP of the constant current control chip U2. The second voltage divider circuit of another detection circuit 4 includes resistors R29 and RS8. The resistors R29 and RS8 are connected in series at one end to a DC power supply, and at the other end to an electronic switch Q4 connected in series with ground. A resistor R33 is connected in series with the control end of the electronic switch Q4 and connected to the node between resistors R31 and R35. The node between resistors R29 and RS8 (the output end of the second voltage divider circuit) is connected to the loop feedback pin COMP of the constant current control chip U2. The resistance values ​​of resistors RS8 and RS9 are different. Using this second voltage divider circuit, the circuit structure is simple, easy to implement, and low cost. However, this is not limiting. In other embodiments, the second voltage divider circuit can also be implemented using other existing voltage divider circuits.

[0030] In this specific embodiment, the electronic switches Q4 and Q5 are preferably implemented using NMOS tubes, which have high sensitivity, low power consumption, and high reliability, but are not limited to this. In some embodiments, the electronic switches Q4 and Q5 can also use other existing electronic switches, such as transistors.

[0031] Preferably, the first voltage divider circuit of the two-way detection circuit 4 further includes capacitors C15 and C16, respectively. The capacitors C15 and C16 are respectively connected between the output end of the first voltage divider circuit of the two-way detection circuit 4 and the ground. The specific connection relationship is detailed in Figure 2 , capacitors C15 and C16 are used for filtering to improve the stability of the output voltage of the first voltage divider circuit, thereby improving reliability.

[0032] Preferably, the first voltage divider circuits of the two detection circuits 4 further include voltage regulator diodes D10 and D11, respectively. The voltage regulator diodes D10 and D11 are respectively connected between the output end of the first voltage divider circuit of the two detection circuits 4 and the ground, and are used to protect the electronic switches Q4 and Q5 to avoid being burned or mistakenly turned on, thereby improving safety and reliability.

[0033] Preferably, in this specific embodiment, a diode D9 is further included, and the node between the resistor R29 and RS8 and the node between the resistor R29 and RS9 are connected to the negative end of the diode D9, and the positive end of the diode D9 is connected to the loop feedback pin COMP of the constant current control chip U2. The diode D9 is used to perform voltage clamping on the loop feedback pin COMP.

[0034] In this specific embodiment, the DC power supply is the power supply VCC of the constant current control chip U2, which is easy to implement, but is not limited to this.

[0035] In this specific embodiment, the rectifier circuit 21 adopts a full-wave rectifier bridge. Figure 2 , I will not go into details here, using a full-wave rectifier bridge makes the current more stable and the efficiency higher, but it is not limited to this.

[0036] In this specific embodiment, the constant current drive circuit 22 is a BOOST boost circuit composed of a constant current control chip U2. Figure 2 This will not be elaborated. Of course, in some embodiments, the constant current driving circuit 22 may also be various existing constant current driving circuits such as a BUCK step-down circuit.

[0037] In this specific embodiment, the LED light source 3 is connected to the interface CN2. The LED light source 3 can be any existing LED light source, such as an LED light source composed of multiple LED lamp beads connected in series or in parallel, and can be white light, red light or other colors.

[0038] In this specific embodiment, the model of the constant current control chip U2 is BP3266A, but it is not limited thereto. Any constant current control chip having a loop feedback pin COMP will suffice.

[0039] Furthermore, in this embodiment, fuses F4 and F3 are connected in series to the two live wire output terminals L1 and L2 of the three-stage selection switch circuit 1, respectively, to avoid overcurrent heating and burning of the circuit, thereby improving safety and reliability.

[0040] Working principle:

[0041] When the three-stage selection switch circuit 1 selects the live wire output terminal L2 and the neutral wire N to be connected to the mains, one path of the mains is rectified by the rectifier circuit 21 and outputs DC power to power the constant current drive circuit 22. The other path is divided by the resistors R31 and 35 of the detection circuit 4 and provides voltage to the electronic switch Q4, so that the switch Q4 is turned on. The DC power supply is output through the resistor R29 and RS8, and the loop feedback pin COMP of the constant current control chip U2 obtains the first voltage through the diode D9. The constant current control chip U2 controls the constant current drive circuit 22 to output the first output current value to light up the LED lamp source 3 and obtain light of the first brightness.

[0042] When the three-stage selection switch circuit 1 selects the live wire output terminal L1 and the neutral wire N to connect to the mains, one path of the mains is rectified by the rectifier circuit 21 and outputs DC power to power the constant current drive circuit 22. The other path of the mains is divided by the resistors R30 and 34 of the detection circuit 4 and provides voltage to the electronic switch Q5, so that the switch Q5 is turned on. The DC power supply VCC is output through the resistors R29 and RS9. The loop feedback pin COMP of the constant current control chip U2 obtains the second voltage through the diode D9. The constant current control chip U2 controls the constant current drive circuit 22 to output the second output current value to light up the LED lamp source 3 and obtain light of the second brightness.

[0043] When the three-stage selection switch circuit 1 selects the live wire output terminals L1 and L2 and the neutral wire N and is connected to the mains at the same time, one path of the mains is rectified by the rectifier circuit 21 and outputs DC power to power the constant current drive circuit 22. The other path of the mains is divided by the resistors R30 and 34 of the detection circuit 4 and provides a voltage to the electronic switch Q5, so that the switch Q5 is turned on. The resistors R31 and 35 are divided and provide a voltage to the electronic switch Q4, so that the switch Q4 is turned on. The DC power supply VCC is divided and output by the resistors R29, RS8 and RS9. The loop feedback pin COMP of the constant current control chip U2 obtains a third voltage through the diode D9. The constant current control chip U2 controls the constant current drive circuit 22 to output a third output current value to light up the LED lamp source 3 and obtain light of a third brightness, thereby realizing three-stage dimming control.

[0044] The present invention also provides an LED lamp provided with the three-stage dimming control circuit of the LED lamp.

[0045] Although the present invention has been particularly shown and described in conjunction with preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims, and all such changes are within the scope of protection of the present invention.

Claims

1. A three-stage dimming control circuit for an LED lamp, comprising a three-stage selector switch circuit, a drive power circuit, an LED light source, and two detection circuits, wherein the input of the drive power circuit is connected to the output of the three-stage selector switch circuit, the output of the drive power circuit is connected to the LED light source, and the inputs of the two detection circuits are respectively connected to the two live wire outputs of the three-stage selector switch circuit. The circuit is characterized in that: The output ends of the two detection circuits are connected to the loop feedback pin COMP of the constant current control chip of the driving power supply circuit. The output voltages of the output ends of the two detection circuits are different. The constant current control chip is used to control the output current according to the voltage of the loop feedback pin COMP.

2. The three-stage dimming control circuit for LED lamp according to claim 1, characterized in that: The detection circuit includes a first voltage divider circuit, a second voltage divider circuit and an electronic switch. The input end of the first voltage divider circuit is connected to the live wire output end of the three-stage selection switch circuit, the output end of the first voltage divider detection circuit is connected to the control end of the electronic switch, the input end of the second voltage divider circuit is connected to a DC power supply, the output end of the second voltage divider circuit is connected to the loop feedback pin COMP of the constant current control chip, and the electronic switch is connected in series in the power supply circuit of the second voltage divider circuit.

3. The three-stage dimming control circuit for LED lamp according to claim 2, characterized in that: The electronic switch is implemented by an NMOS tube.

4. The three-stage dimming control circuit for LED lamp according to claim 2, characterized in that: The first voltage divider circuit further includes a capacitor connected between the output end of the first voltage divider circuit and the ground.

5. The three-stage dimming control circuit for LED lamp according to claim 2 or 4, characterized in that: The first voltage-dividing circuit further includes a voltage-stabilizing diode connected between the output end of the first voltage-dividing circuit and the ground.

6. The three-stage dimming control circuit for LED lamp according to claim 2, characterized in that: The second voltage divider circuit further includes a diode D9. The output end of the second voltage divider circuit is connected in reverse series with the diode D9 and connected to the loop feedback pin COMP of the constant current control chip.

7. The three-stage dimming control circuit for LED lamp according to claim 1, characterized in that: The driving power supply circuit includes a rectifier circuit and a constant current driving circuit. The input end of the rectifier circuit is connected to the output end of the three-stage selection switch circuit, the output end of the rectifier circuit is connected to the input end of the constant current driving circuit, and the output end of the constant current driving circuit is connected to the LED light source. The rectifier circuit adopts a full-wave rectifier bridge.

8. The three-stage dimming control circuit for LED lamp according to claim 7, characterized in that: The constant current driving circuit is a BOOST boost circuit composed of a constant current control chip U2.

9. The three-stage dimming control circuit for LED lamp according to claim 1, characterized in that: Fuses are respectively connected in series to the two live wire output ends of the three-stage selection switch circuit.

10. An LED lamp, characterized in that: A three-stage dimming control circuit for an LED lamp according to any one of claims 1 to 9 is provided.

Images