Double loop controlled LED (Light Emitting Diode) driving circuit
A technology of LED drive and double-loop control, which is applied in the direction of lamp circuit layout, electric light source, lighting device, etc., can solve the problems of temperature rise, high power consumption of constant current diodes, and lower power supply efficiency, so as to increase safety performance and reduce heat generation , The effect of improving power efficiency
Inactive Publication Date: 2013-05-01
MLS
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Since the constant current diode is connected in series with the load, the LED load voltage is basically unchanged. When the input voltage is not equal to the load voltage, the voltage difference will be fully added to the constant current diode. The larger the voltage difference, the greater the power consumption of the constant current diode. The temperature rises sharply, if the heat dissipation is not good, it will endanger the stability and safety of the circuit
[0003] In addition, the current household LED lighting drivers tend to be low-cost and miniaturized, and the traditional RC buck is popular, but its inherent defects (non-isolation, non-constant current, overvoltage shock) limit its application in LED lighting. The structure is complex, the cost is high, and it is not suitable for high-voltage and low-current LED driving; the linear power supply has the advantages of simple structure and good electromagnetic compatibility, and is the first choice for high-voltage and low-current driving. However, because the adjustment tube of the linear power supply is connected in series with the LED , the power consumption of the adjustment tube is large, and a large amount of heat is generated, which reduces the efficiency of the power supply and increases the difficulty of the heat dissipation design of the lamp
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[0017] Such as figure 1 As shown, it is a dual-loop control LED drive circuit, including an AC power supply 1, a rectifier circuit 2, a load circuit 3 connected in sequence, an output current sampling control loop 4, and an input voltage sampling control loop 5; wherein, the load circuit 3 Including several LED light sources connected in series, power transistor Q1, sampling resistor Rs and bias resistor Rb; the collector of power transistor Q1 is connected to the negative pole of the LED light source, the emitter is connected to the resistor Rs, and between the base and the output positive pole of the rectifier circuit 2 Connect bias resistor Rb.
[0018] It should be pointed out that the rectifier circuit 2 of the present invention is not limited to the full-bridge rectifier circuit, and other commonly used rectifier circuits 2 belong to conventional designs, such as half-bridge rectifier circuits and voltage doubler rectifier circuits. In addition, the AC power source 1 is...
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The invention discloses a double loop controlled LED (Light Emitting Diode) driving circuit, which comprises an alternating current power supply, a rectifying circuit, a load circuit, an output current sampling control loop and an input voltage sampling control loop connected in sequence, wherein the load circuit comprises a plurality of serial or parallel LED light sources, a power triode Q1, a sampling resistor Rs and a bias resistor Rb; the output current sampling control loop comprises a control triode Q2 and a sampling resistor Rs; and the input voltage sampling control loop comprises a control triode Q3 and sampling resistors R1 and R2. By using the double loop controlled LED driving circuit, power consumption of a power tube is reduced along with rise of input voltage, so that the power efficiency is increased, the heating is reduced, and the safety performance of a lamp is enhanced.
Description
technical field [0001] The invention relates to an LED driving circuit, in particular to a double-loop controlled LED driving circuit. Background technique [0002] At present, many LED lamps use a high-voltage low-current drive scheme. Among them, the driving scheme of constant current diode series LED has the advantages of simple circuit and small size. The constant current diode keeps the output current constant within a certain voltage range. When the input voltage fluctuates, it can ensure that the load current is basically unchanged. Therefore it is suitable for use as an LED driver. Since the constant current diode is connected in series with the load, the LED load voltage is basically unchanged. When the input voltage and the load voltage are not equal, the voltage difference will be added to the constant current diode. The larger the voltage difference, the greater the power consumption of the constant current diode. The temperature rises sharply, and if the heat ...
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IPC IPC(8): H05B37/02
Inventor 张庆蓉周党培刘天明
Owner MLS