An LED driving circuit and an LED lamp

Abstract

The present invention relates to the technical field of LED lamps. The present invention discloses an LED driving circuit and an LED lamp. The LED driving circuit includes a first and a second LED module, a linear constant-current driving circuit, an input voltage detection circuit, a first and a second switching circuit, a switching driving circuit, and a unidirectional conduction circuit. The first LED module, the unidirectional conduction circuit, and the second LED module are connected in series in sequence and then connected to the output terminal of the linear constant-current driving circuit. The first LED module is connected in series with the first switching circuit and then connected to the output terminal of the linear constant-current driving circuit. The second switching circuit is connected in series with the second LED module and then connected to the output terminal of the linear constant-current driving circuit. The switching driving circuit is configured to drive both the first switching circuit and the second switching circuit to be disconnected when the input voltage detection circuit detects that the input voltage is high to a certain value; otherwise, drive both the first switching circuit and the second switching circuit to be conductive. The present invention can achieve wide-voltage input and dual-voltage output, has strong adaptability, and has a simple circuit structure and low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of LED lamps, and particularly relates to an LED driving circuit and an LED lamp. Background Art

[0002] Due to its many advantages such as energy saving, long life, and environmental friendliness, LED lamps have been more and more widely used in various places, including civil lighting, commercial lighting, industrial lighting and other lighting places, as well as decorative places such as art galleries and museums.

[0003] When an LED lamp works, an LED driving circuit is required for driving. The LED linear constant current driving circuit is widely used in LED lamps due to its characteristics of low cost, simple structure, high efficiency, and small size. However, the traditional LED linear constant current driving circuit cannot have a wide voltage input, and its output voltage range is limited, resulting in more restrictions on the selection of LED light sources. The finished product market is limited by voltage, and a wide voltage unified solution cannot be achieved, with poor adaptability.

[0004] Although there are some LED linear constant current driving circuits that can achieve wide voltage input now, they need to use multiple linear constant current source modules to achieve, with a relatively complex circuit structure and high cost, which is not conducive to cost control. Summary of the Invention

[0005] The purpose of the present invention is to provide an LED driving circuit and an LED lamp to solve the above-mentioned existing technical problems.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: an LED driving circuit, including a first LED module, a second LED module, a linear constant current driving circuit, an input voltage detection circuit, a first switch circuit, a second switch circuit, a switch driving circuit, and a unidirectional conduction circuit. The first LED module, the unidirectional conduction circuit, and the second LED module are connected in series in sequence and then connected to the output end of the linear constant current driving circuit. The first LED module is connected in series with the first switch circuit and then connected to the output end of the linear constant current driving circuit. The second switch circuit is connected in series with the second LED module and then connected to the output end of the linear constant current driving circuit. The switch driving circuit is configured to drive both the first switch circuit and the second switch circuit to disconnect when the input voltage detection circuit detects that the input voltage is higher than a certain value; otherwise, drive both the first switch circuit and the second switch circuit to conduct.

[0007] Further, the unidirectional conduction circuit is implemented by a diode.

[0008] Further, the first switch circuit is implemented by an NMOS transistor Q1.

[0009] Furthermore, a capacitor C1 is connected between the gate and the source of the NMOS transistor Q1.

[0010] Further, the second switch circuit is implemented by using an NMOS transistor Q2.

[0011] Furthermore, a capacitor C2 is connected between the gate and the source of the NMOS transistor Q2.

[0012] Further, the input voltage detection circuit includes a resistor R1, a resistor R2, a resistor R3, an electrolytic capacitor EC2, and a zener diode ZD1. The resistors R1, R2, and R3 are connected in series in turn and then connected between the input ends of the linear constant current driving circuit. The electrolytic capacitor EC2 and the zener diode ZD1 are respectively connected in parallel with the resistor R3. The node between the resistor R2 and the resistor R3 is the output end of the input voltage detection circuit.

[0013] Further, the switch driving circuit is composed of an optocoupler U2 and an optocoupler U3. The input ends of the optocoupler U2 and the optocoupler U3 are connected in series and then connected to the output end of the input voltage detection circuit. The output ends of the optocoupler U2 and the optocoupler U3 respectively drive the first switch circuit and the second switch circuit.

[0014] Furthermore, a resistor R4 is serially connected to the input loop of the optocoupler U2 and the optocoupler U3.

[0015] The present invention also provides an LED lamp provided with the above-mentioned LED driving circuit.

[0016] Advantageous technical effects of the present invention:

[0017] The present invention can achieve wide voltage input (100V - 264V) and dual voltage output, has strong adaptability, can be applicable to various lamp types, has less limitation in selecting LED light sources, and is applicable to the global universal mains power supply (100V - 264V); and only one linear constant current source module is needed, the circuit structure is relatively simple, is easy to implement, has low cost, and improves the market competitiveness. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0019] Figure 1 It is the specific circuit diagram of the LED driving circuit according to Embodiment 1 of the present invention. Detailed Embodiments

[0020] To further illustrate the embodiments, the present invention provides accompanying drawings. These drawings are a part of the disclosure of the present invention, mainly used to illustrate the embodiments and can be combined with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0022] Embodiment 1

[0023] As Figure 1 shown, an LED driving circuit includes a first LED module 1, a second LED module 2, a linear constant current driving circuit, an input voltage detection circuit, a first switching circuit, a second switching circuit, a switching driving circuit, and a unidirectional conduction circuit. The linear constant current driving circuit can be various existing linear constant current driving circuits composed of a single linear constant current chip.

[0024] In this specific embodiment, the linear constant current driving circuit includes a rectifier bridge BG, a filter electrolytic capacitor EC1, and a linear constant current chip U1. The input end of the rectifier bridge BG is connected to an AC power supply (mains electricity). The positive output end of the rectifier bridge BG is connected to the positive output end Vbus of the linear constant current driving circuit. The negative output end of the rectifier bridge BG is grounded. The first end of the linear constant current chip U1 is used as the negative output end of the linear constant current driving circuit to connect to the negative pole of the LED light source. The second end of the linear constant current chip U1 is grounded. The filter electrolytic capacitor EC1 is connected between the positive output end and the negative output end of the rectifier bridge BG. For a more specific circuit structure, please refer to Figure 1 , but not limited thereto. In other embodiments, other existing linear constant current driving circuit structures can also be used to implement it.

[0025] The first LED module 1, the unidirectional conduction circuit, and the second LED module 2 are connected in series in sequence and then connected to the output end of the linear constant current driving circuit. Specifically, the positive pole of the first LED module 1 is connected to the positive output end Vbus of the linear constant current driving circuit. The negative pole of the first LED module 1 is connected in series with the unidirectional conduction circuit in the forward direction to the positive pole of the second LED module 2. The negative pole of the second LED module 2 is connected to the negative output end of the linear constant current driving circuit (the first end of the linear constant current chip U1).

[0026] In this specific embodiment, both the first LED module 1 and the second LED module 2 are composed of a plurality of LED beads connected in series. The number of LED beads in the first LED module 1 and the second LED module 2 can be selected according to actual needs, which can be easily achieved by those skilled in the art and will not be elaborated here. Of course, in some embodiments, the first LED module 1 and the second LED module 2 can also be each composed of one LED bead.

[0027] Preferably, in this specific embodiment, the one-way conduction circuit is implemented by a diode D1. The circuit structure is simple, easy to implement, and has low cost. However, it is not limited to this. In other embodiments, the one-way conduction circuit can also be implemented by other existing one-way conduction circuits, such as a one-way conduction circuit composed of a triode, a MOS tube, etc.

[0028] Specifically, the positive terminal of the diode D1 is connected to the negative terminal of the first LED module 1, and the negative terminal of the diode D1 is connected to the positive terminal of the second LED module 2.

[0029] The first LED module is connected in series with the first switch circuit and then connected to the output terminal of the linear constant current drive circuit. The second switch circuit is connected in series with the second LED module and then connected to the output terminal of the linear constant current drive circuit. Specifically, the negative terminal of the first LED module 1 is connected in series with the first switch circuit and connected to the first terminal of the linear constant current chip U1. The positive terminal of the second LED module 2 is connected in series with the second switch circuit and connected to the positive output terminal Vbus of the linear constant current drive circuit.

[0030] In this specific embodiment, the first switch circuit is preferably implemented by an NMOS transistor Q1, which has a large current tolerance and low power consumption. Specifically, the drain of the NMOS transistor Q1 is connected to the negative terminal of the first LED module 1, the source of the NMOS transistor Q1 is connected to the first terminal of the linear constant current chip U1, and the gate of the NMOS transistor Q1 is connected to the drive output terminal of the switch drive circuit. Of course, in other embodiments, the first switch circuit can also be implemented by other existing switch circuits.

[0031] In this specific embodiment, the second switch circuit is preferably implemented by an NMOS transistor Q2, which has a large current tolerance and low power consumption. Specifically, the drain of the NMOS transistor Q2 is connected to the positive output terminal Vbus of the linear constant current drive circuit, the source of the NMOS transistor Q21 is connected to the positive terminal of the second LED module 2, and the gate of the NMOS transistor Q2 is connected to the drive output terminal of the switch drive circuit. Of course, in other embodiments, the second switch circuit can also be implemented by other existing switch circuits.

[0032] The switch drive circuit is configured to drive both the first switch circuit and the second switch circuit to be disconnected when the input voltage detection circuit detects that the input voltage is high to a certain value; otherwise, drive both the first switch circuit and the second switch circuit to be conductive.

[0033] In this specific embodiment, the switch driving circuit is composed of optocouplers U2 and U3. The input ends of optocouplers U2 and U3 are connected in series between the output end of the input voltage detection circuit and the ground. The two output ends of optocoupler U2 are respectively connected to the gate and source of NMOS transistor Q1, and the two output ends of optocoupler U3 are respectively connected to the gate and source of NMOS transistor Q2. With this switch driving circuit, NMOS transistors Q1 and Q2 can be turned on and off simultaneously, avoiding the burnout of NMOS transistors or LED modules caused by the asynchronism between them, and the circuit structure is simple and easy to implement.

[0034] In this specific embodiment, both optocouplers U2 and U3 are implemented using optocouplers of the photosensitive triode type, but this is not limited thereto.

[0035] Of course, in other embodiments, the switch driving circuit can also be implemented using other existing switch driving circuits.

[0036] Furthermore, in this specific embodiment, a resistor R4 is also included. Resistor R4 is connected in series in the input loop of optocouplers U2 and U3 to adjust the current flowing through the input ends of optocouplers U2 and U3 to protect optocouplers U2 and U3.

[0037] Preferably, in this specific embodiment, a capacitor C1 is connected between the gate and source of NMOS transistor Q1, and a capacitor C2 is connected between the gate and source of NMOS transistor Q2 to avoid stroboscopic phenomena.

[0038] In this specific embodiment, the input voltage detection circuit includes resistors R1, R2, R3, electrolytic capacitor EC2, and zener diode ZD1. Resistors R1, R2, and R3 are connected in series in turn between the outputs of the rectifier bridge BG (between the input ends of the linear constant current driving circuit). Electrolytic capacitor EC2 and zener diode ZD1 are respectively connected in parallel with resistor R3. The node between resistors R2 and R3 (the output end of the input voltage detection circuit) is connected to the ground in series with the input ends of optocouplers U2 and U3 and resistor R4. With this input voltage detection circuit, a relatively large driving current can be provided for optocouplers U2 and U3, and the driving is more stable. However, this is not limited thereto. In other embodiments, the input voltage detection circuit can also be implemented using other existing voltage detection circuits. For example, electrolytic capacitor EC2 can be replaced with an ordinary capacitor, etc.

[0039] Working process:

[0040] When the input voltage is high, the voltage of the electrolytic capacitor EC2 is sufficient to drive the optocouplers U2 and U3 to conduct, pulling down the gates of the NMOS transistors Q1 and Q2. The NMOS transistors Q1 and Q2 are turned off, and the current at the positive output terminal Vbus of the linear constant-current driving circuit flows from the first LED module 1 through the diode D1 to the second LED module 2 and then to the linear constant-current chip U1, realizing series output with a relatively high output voltage.

[0041] When the input voltage is low, the voltage of the electrolytic capacitor EC2 is too low to drive the optocouplers U2 and U3 to conduct. The NMOS transistors Q1 and Q2 conduct, and the current at the positive output terminal Vbus of the linear constant-current driving circuit splits into two paths. One path goes through the first LED module 1 to the NMOS transistor Q1 and then to the linear constant-current chip U1; the other path goes through the second LED module 2 to the NMOS transistor Q2 and then to the linear constant-current chip U1. The diode D1 is reversely cut off, realizing parallel output of the first LED module 1 and the second LED module 2 with a relatively low output voltage. Thus, wide-voltage input (100V - 264V) and dual-voltage output can be achieved, with strong adaptability, applicable to various types of lamps, less restricted in the selection of LED light sources, and applicable to the global universal mains (100V - 264V); and only one linear constant-current source module (linear constant-current chip) is needed, the circuit structure is relatively simple, easy to implement, with low cost, and improving the market competitiveness.

[0042] Embodiment 2

[0043] The difference between this embodiment and Embodiment 1 is that both the first switching circuit and the second switching circuit in this embodiment are implemented using NPN transistors.

[0044] The present invention also provides an LED lamp provided with the above-mentioned LED driving circuit. The LED lamp can be various LED lamps such as panel lights, ceiling lights, downlights, etc.

[0045] Although the present invention has been specifically shown and described in combination with the preferred embodiments, those skilled in the art should understand that various changes can be made to the present invention in terms of form and details without departing from the spirit and scope of the present invention defined by the appended claims, and all of them fall within the protection scope of the present invention.

Claims

1. An LED driving circuit, characterized in that: It includes a first LED module, a second LED module, a linear constant-current driving circuit, an input voltage detection circuit, a first switching circuit, a second switching circuit, a switching driving circuit and a unidirectional conduction circuit. The first LED module, the unidirectional conduction circuit and the second LED module are connected in series in sequence and then connected to the output end of the linear constant-current driving circuit. The first LED module is connected in series with the first switching circuit and then connected to the output end of the linear constant-current driving circuit. The second switching circuit is connected in series with the second LED module and then connected to the output end of the linear constant-current driving circuit. The switching driving circuit is configured to drive both the first switching circuit and the second switching circuit to be disconnected when the input voltage detection circuit detects that the input voltage is higher than a certain value; otherwise, drive both the first switching circuit and the second switching circuit to be conducted.

2. The LED driving circuit according to claim 1, characterized in that: The unidirectional conduction circuit is implemented by a diode.

3. The LED driving circuit according to claim 1, characterized in that: The first switching circuit is implemented by an NMOS transistor Q1.

4. The LED driving circuit according to claim 3, characterized in that: A capacitor C1 is connected between the gate and the source of the NMOS transistor Q1.

5. The LED driving circuit according to claim 1, characterized in that: The second switching circuit is implemented by an NMOS transistor Q2.

6. The LED driving circuit according to claim 5, characterized in that: A capacitor C2 is connected between the gate and the source of the NMOS transistor Q2.

7. The LED driving circuit according to claim 1, characterized in that: The input voltage detection circuit includes a resistor R1, a resistor R2, a resistor R3, an electrolytic capacitor EC2 and a voltage stabilizing diode ZD1. The resistor R1, the resistor R2 and the resistor R3 are connected in series in sequence and then connected between the input ends of the linear constant-current driving circuit. The electrolytic capacitor EC2 and the voltage stabilizing diode ZD1 are respectively connected in parallel with the resistor R3. The node between the resistor R2 and the resistor R3 is the output end of the input voltage detection circuit.

8. The LED driving circuit according to claim 1, characterized in that: The switching driving circuit is composed of an optocoupler U2 and an optocoupler U3. The input ends of the optocoupler U2 and the optocoupler U3 are connected in series and then connected to the output end of the input voltage detection circuit. The output ends of the optocoupler U2 and the optocoupler U3 respectively drive the first switching circuit and the second switching circuit.

9. The LED driving circuit according to claim 8, characterized in that: It further includes a resistor R4, and the resistor R4 is connected in series in the input loop of the optocoupler U2 and the optocoupler U3.

10. An LED lamp, characterized in that: It is provided with the LED driving circuit according to any one of claims 1-9.

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