LED brightness switching circuit

Abstract

The utility model provides an LED brightness switching circuit, which comprises an LED lamp circuit, a high-brightness driving circuit for controlling the lighting of a vehicle lamp and a power supply for supplying power to the LED lamp circuit, and the LED lamp circuit is connected in series between the power supply and the driving circuit. The highlight driving circuit comprises a triode T1 and an MOS tube T3, the output end of the LED lamp circuit is connected with the collector electrode of the triode T1, a resistor R4 is connected in series between the emitter electrode of the triode T1 and the source electrode of the MOS tube T3, the grid electrode of the MOS tube T3 is connected with a power supply, the base electrode of the triode T1 is connected with the input end of the LED lamp circuit, and the base electrode of the triode T1 is connected with the output end of the LED lamp circuit. The high-brightness driving circuit comprises a triode T2, an MOS tube T4 and a resistor R6, the low-brightness driving circuit comprises a triode T2, an MOS tube T4 and a resistor R6, the high-brightness driving circuit and the low-brightness driving circuit are identical in circuit structure and connection relation, and the resistor R6 and the resistor R4 are different in resistance value. According to the utility model, the production cost of the brightness switching circuit of the LED lamp circuit can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of LED lamp brightness switching, in particular to an LED brightness switching circuit. Background Art

[0002] At present, the automobile headlights have developed to the fourth generation. The first generation of automobile light sources is the direct combustion of fuel; the second generation of automobile light sources is incandescent lamps; the third generation of automobile light sources is gas discharge lamps; the fourth generation of automobile light sources is semiconductor light emitting diodes (LEDs). LED headlights are more efficient than ordinary automobile headlights because light emitting diodes directly convert electrical energy into light energy instead of heating objects through heat energy. The power consumption is only 1 / 10 of that of traditional headlights, so it can better save fuel consumption and protect automobile circuits from being burned by excessive load current.

[0003] However, most of the LED headlights currently used control the operation of the headlights through a control chip and a sampling chip. The sampling chip monitors the current and voltage data flowing through the LED headlights, and the control chip controls the power supply based on the voltage and current data, resulting in high cost of the brightness control circuit of the LED headlights. Utility Model Content

[0004] In view of this, the problem to be solved by the present invention is to provide an LED brightness switching circuit, which can reduce the cost of the LED brightness switching circuit.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0006] An LED brightness switching circuit comprises an LED lamp circuit, a high brightness driving circuit for controlling the lighting of a vehicle lamp, and a power supply for supplying power to the LED lamp circuit, wherein the LED lamp circuit is connected in series between the power supply and the high brightness driving circuit;

[0007] The highlight driving circuit comprises a transistor T1 and a MOS transistor T3, the output end of the LED lamp circuit is connected to the collector of the transistor T1, and a resistor R4 is connected in series between the emitter of the transistor T1 and the source of the MOS transistor T3;

[0008] The output end of the power supply is provided with a P1 port, the gate of the MOS tube T3 is connected to the P1 port, and the base of the transistor T1 is connected to the input end of the LED lamp circuit.

[0009] Furthermore, the output end of the LED lamp circuit is connected to a low-brightness driving circuit, and the low-brightness driving circuit includes a transistor T2, a MOS transistor T4 and a resistor R6;

[0010] The output end of the power supply is provided with a P2 port, the circuit structures and connection relationships of the high-brightness driving circuit and the low-brightness driving circuit are completely the same, the gate of the MOS tube T4 is connected to the P2 port, and the resistance values ​​of the resistor R6 and the resistor R4 are different.

[0011] Furthermore, a diode D1 is connected in series between the P1 port and the LED lamp circuit, and a diode D2 is connected in series between the P2 port and the LED lamp circuit.

[0012] Furthermore, a resistor R1 and a diode D3 are connected in series between the input end of the LED lamp circuit and the ground, a resistor R2 is connected in series between the anode of the diode D3 and the base of the transistor T1, and a resistor R3 is connected in series between the anode of the diode D3 and the base of the transistor T2 for overvoltage protection.

[0013] Furthermore, the LED lamp circuit includes a lamp LED1, a lamp LED2 and a lamp LED3 connected in series.

[0014] The advantages and positive effects of the utility model are:

[0015] By respectively setting a high-brightness driving circuit and a low-brightness driving circuit between the LED lamp circuit and the ground, the corresponding driving circuits are controlled to be turned on according to the brightness requirements, so as to adjust the brightness of the LED lamp circuit.

[0016] Transistor T1 and transistor T2 are respectively arranged in the high-brightness driving circuit and the low-brightness driving circuit. The bases of transistor T1 and transistor T2 are connected to the input end of the LED lamp circuit through resistor R1. When the output voltage of the power supply is too high, transistor T1 or transistor T2 is turned on to perform overvoltage protection, thereby increasing the service life of the LED lamp circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 This is an overall system diagram of an LED brightness switching circuit of the utility model;

[0019] Figure 2 The utility model discloses an overall circuit diagram of an LED brightness switching circuit. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0022] The utility model provides a LED brightness switching circuit, such as Figure 1 to Figure 2 As shown, it includes a power supply for providing electric energy, the output end of the power supply is connected to the P1 port through a first switch, and the output end of the power supply is connected to the P2 port through a second switch. Whether the first switch or the second switch is closed is controlled to supply power to the LED lamp circuit.

[0023] A diode D1 is connected in series between the P1 port and the input end of the LED lamp circuit, and a diode D2 is connected in series between the P2 port and the LED lamp circuit. The diode D1 and the diode D2 together form a current reverse flow prevention circuit to prevent current reverse flow. An embodiment of the present application is: the LED lamp circuit includes a lamp LED1, a lamp LED2 and a lamp LED3 connected in series.

[0024] The output end of the LED lamp circuit is respectively connected to the high-brightness driving circuit and the low-brightness driving circuit. The circuit structures and connection relationships of the high-brightness driving circuit and the low-brightness driving circuit are exactly the same. Take the high-brightness connection circuit as an example: it includes a transistor T1 and a MOS tube T3. The output end of the LED lamp circuit is connected to the collector of the transistor T1. A resistor R4 is connected in series between the emitter of the transistor T1 and the source of the MOS tube T3. The gate of the MOS tube T3 is connected to the P1 port. A resistor R10 is connected in series between the gate of the MOS tube T3 and the ground. The drain of the MOS tube T3 is electrically connected to the ground. The base of the transistor T1 is connected to the input end of the LED lamp circuit.

[0025] The operation process of the highlight drive circuit is: the first switch is turned on, the transistor T1 and the MOS tube T3 are turned on, and the current output by the power supply passes through the LED lamp circuit and the highlight drive circuit in turn. The smaller the resistance value of the resistor R4, the greater the current value flowing through the LED lamp circuit, and the higher the brightness of the LED lamp circuit. In the actual production process, the resistance value of the resistor R4 can be adjusted according to the actual brightness requirements of the LED lamp circuit.

[0026] The low-brightness driving circuit includes a transistor T2, a MOS tube T4, a resistor R6 and a resistor R11. The circuit structure and connection relationship of the high-brightness driving circuit and the low-brightness driving circuit are exactly the same, and only the resistance values ​​of the resistor R6 and the resistor R4 are different.

[0027] Resistor R4 is connected in parallel with resistor R5, and the resistance of resistor R4 and resistor R5 are the same, which can improve the stability of the resistance of resistor R4. When the resistance of one of resistor R4 or resistor R5 changes, the total resistance of resistor R4 and resistor R5 fluctuates slightly, which can extend the effectiveness of the high-brightness driving circuit and thus extend the service life of the high-brightness driving circuit. In the low-brightness driving circuit, resistor R6 is connected in parallel with resistor R7.

[0028] A resistor R1 and a diode D3 are connected in series between the input end and the ground of the LED lamp circuit, a resistor R2 is connected in series between the anode of the diode D3 and the base of the transistor T1, and a resistor R3 is connected in series between the anode of the diode D3 and the base of the transistor T2, so as to provide overvoltage protection.

[0029] The working process is: when the power supply voltage is normal, the output voltage makes the MOS tube T3 and the transistor T1 conduct. When the power output voltage is too high, the diode D3 breaks down to shunt the current, and the resistor R1 divides the voltage to reduce the voltage at the input end of the LED lamp circuit.

[0030] The above embodiments of the utility model are described in detail, but the above contents are only preferred embodiments of the utility model and cannot be considered to limit the scope of implementation of the utility model. All equivalent changes and improvements made within the scope of the utility model should still fall within the scope of this patent.

Claims

1. An LED brightness switching circuit, characterized in that: It includes an LED lamp circuit, a high-brightness driving circuit for controlling the lighting of the vehicle lamp, and a power supply for supplying power to the LED lamp circuit, wherein the LED lamp circuit is connected in series between the power supply and the high-brightness driving circuit; The highlight driving circuit comprises a transistor T1 and a MOS transistor T3, the output end of the LED lamp circuit is connected to the collector of the transistor T1, and a resistor R4 is connected in series between the emitter of the transistor T1 and the source of the MOS transistor T3; The output end of the power supply is provided with a P1 port, the gate of the MOS tube T3 is connected to the P1 port, and the base of the transistor T1 is connected to the input end of the LED lamp circuit.

2. The LED brightness switching circuit according to claim 1, characterized in that: The output end of the LED lamp circuit is connected to a low-brightness driving circuit, and the low-brightness driving circuit includes a transistor T2, a MOS tube T4 and a resistor R6; The output end of the power supply is provided with a P2 port, the circuit structures and connection relationships of the high-brightness driving circuit and the low-brightness driving circuit are completely the same, the gate of the MOS tube T4 is connected to the P2 port, and the resistance values ​​of the resistor R6 and the resistor R4 are different.

3. The LED brightness switching circuit according to claim 1, characterized in that: A diode D1 is connected in series between the P1 port and the LED lamp circuit, and a diode D2 is connected in series between the P2 port and the LED lamp circuit.

4. The LED brightness switching circuit according to claim 1, characterized in that: A resistor R1 and a diode D3 are connected in series between the input end of the LED lamp circuit and the ground, a resistor R2 is connected in series between the anode of the diode D3 and the base of the transistor T1, and a resistor R3 is connected in series between the anode of the diode D3 and the base of the transistor T2 for overvoltage protection.

5. The LED brightness switching circuit according to claim 1, characterized in that: The LED lamp circuit comprises a lamp LED1, a lamp LED2 and a lamp LED3 connected in series.

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