At present, many LED lamps and lanterns produced by many manufacturers (such as guardrails, lamp cups, projecting lights, yard lights, etc.) use resistance and capacity to depressurization, and then add a stable voltage diode to LED power supply, so that the way to drive LED has great defects, first is low efficiency, a large amount of electrical energy is consumed on the step-down resistance, and even can be used. It can exceed the electrical energy consumed by LED and can not provide large current drive, because the greater the current, the greater the power consumed on the step-down resistor, and it is impossible to ensure that the LED current does not exceed its normal working requirements. When the product is designed, the voltage of the LED ends will be reduced to the power supply, so that the luminance of the LED is sacrificed at the expense of the power. . Using resistance and capacity to drive LED, the brightness of LED can not be stable. When the voltage of power supply is low, the brightness of LED becomes darker, and when the voltage of power supply is high, the brightness of LED becomes brighter. Of course, the biggest advantage of resistance and capacity depressurization to drive LED is low cost, so there are still some LED lighting enterprises in this way.
Constant current source driving is the best LED driving method. It adopts constant current source driver and does not need to connect the current limiting resistor in series in the output circuit. The current flowing on the LED is also not affected by external power supply voltage change, ambient temperature change, and discreteness of LED parameters. Influence, can keep the electric current constant, give full play to various excellent characteristic of LED.
The LED constant current power supply is used to power the LED lamps. Since the current flowing through the LEDs is automatically detected and controlled during power supply operation, there is no need to worry about high current flowing through the LEDs at the instant of power-on, and there is no need to worry about short-circuit burning of the load. Bad power supply.
The constant current drive method can avoid the change of the LED forward voltage and cause the current change. At the same time, the constant current makes the brightness of the LED stable, and it is also convenient for the LED lamp factory to ensure the consistency of the product when mass production is carried out. Therefore, many manufacturers have already Fully aware of the importance of the drive power supply, many LED lamp manufacturers have given up the constant voltage mode, and choose a slightly higher constant current mode to drive the LED lamps.
Some manufacturers are concerned that the use of electrolytic capacitors in the power driver board will affect the life of the power supply. This is actually a misunderstanding. For example, if a 105-degree, 8,000-hour high-temperature electrolytic capacitor is used, the estimated lifetime of electrolytic capacitors according to the prevailing method is 10 degrees per degree. , life expectancy doubles, then it works for 16000 hours under 95 degree environment, working life is 32000 hours under 85 degree environment, working life is 64000 hours under 75 degree environment, if the actual working temperature is lower, Then life will be longer! From this point of view, as long as the use of high quality electrolytic capacitors has no effect on the life of the drive power supply!