Light-emitting diode (LED) driving circuit

Abstract

The invention relates to a light-emitting diode (LED) driving circuit, which is used for driving an LED module to work and comprises a transformer, a voltage feedback circuit and a controller. The transformer, the LED module, the voltage feedback circuit and the controller are sequentially and electrically connected. The controller is additionally and electrically connected to the transformer. The voltage feedback circuit comprises a first triode, a second triode, a sampling resistor and an auxiliary power supply. The sampling resistor is connected with the LED module. The emitters of the first triode and the second triode are coupled and connected to the auxiliary power supply. The voltage of the base of the first triode is consistent with voltage consumed by the sampling resistor in the preset constant-current working state of the LED module. The voltage of the base of the second triode is consistent with voltage consumed by the sampling resistor. The voltage feedback circuit determines whether to transmit a trigger signal to the controller or not according to the situation whether the voltage of the base of the first triode is smaller than the voltage of the base of the second triode or not. The controller adjusts current output by the transformer to the LED module according to the situation whether the trigger signal is received or not.

Description

technical field [0001] The present invention relates to an electronic element driving circuit, in particular to a light emitting diode (Light Emitting Diode, LED) driving circuit. Background technique [0002] In the LED driving circuit, a controller usually controls the transformer to output a constant current to the LED, so that the LED can work normally under the driving of the constant current. In order to ensure that the transformer can output a constant current to the LED, a sampling resistor is usually connected in series with the LED, and then the voltage on the sampling resistor is sampled through a voltage sampling circuit connected to the controller. The sampling signal controls the output current of the transformer to the LED. Existing voltage sampling circuits usually include a voltage regulator and a photocoupler or an amplifier and a photocoupler, and the voltage regulator or amplifier has conduction and cutoff corresponding to voltage values ​​in different r...

AI Technical Summary

Problems solved by technology

However, in the way of using the voltage stabilizer and the photocoupler, the resistance value of the sampling resistor is generally large, and the power consumption thereof is also relatively large, resulting in low efficiency of the driving circuit; while the way of using the amplifier and the photocoupler Among them, since the cost of the amplifier is generally high, adding an amplifier will increase the manufacturing cost of the LED drive circuit

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