The minimum limited voltage of 5 common colors LED lights

Time : 2014-12-24 12:58Source :analogtechnologies Author : Analog Click :
The common specifications voltage of LED lights are 12V and 24V, and one team of 12V LED light consists of three pcs LEDs, while24VLED light is made up of six pcs LEDs. Once, some customer requested to reduce the power supply voltage, but here we need to notice that not all colors and all specifications of the LED lights can be used when the power supply voltage reduced, and itcannot be reduced unconditionally. In order to classifythevoltage of what kind of the LED lights can be reduced, first look at the driving voltage of the five common colors single piece LED.
    1.White LED:  3.0~3.3V
    2.Red LED: 1.8~2.2V
    3.Blue LED: 3.0~3.2V
    4.Green LED: 2.9~3.1V
    5.Yellow LED: 1.8~2.0V
The standard dc power supply voltage specifications that are available in the market are 6 V, 9 V, 12 V, 18 V, 24 V, then step-down specifications of LED lights must also be consistent with the above specifications, otherwise the power matching is also a problem.
    A.Using several kinds of common color LED as some examples to illustrate the minimum voltage limit of3 pcs LEDs group.
        1.White LEDs: According to the minimum driving voltage: 3*3.0=9V, if LED light’s power supply is 9V, and this LED light can’t be added a current-limit resistor. If LED lights from other groupsare broken, that will cause the current increase on this group LED light, which results in LED burning. But if adding limiting current resistor on this group LED light, it will be lower than the minimum LED driving voltage, and it will affect the luminous intensity and glowing effect of LED lamp. Therefore, the lowest voltage limit of white LED lights is 12V. 
        2.Red LEDs: According to the minimum driving voltage of 1.8V: 3*1.8V=5.4V, then based on common power supply voltage specification, 6V is fine.As 6V-5.4V=0.6V, we can add 30 ohms current-limit resistor. So the minimum voltage limit of the red LED light is 6V.
        3.Blue LEDs: The minimum voltage limit ofthe blue LED lights is the same as that of the white LED lights,which is 12V.
        4.Green LEDs: According to the minimum driving voltage of 2.9V: 3*2.9V=8.7V, then based on the common power supply voltage specification, 9V is fine. 9V-8.7V=0.3V, we can also add 15 ohms current-limit resistor. So the minimum voltage limit of the green LED lights is 9V.
        5.Yellow LEDs: The minimum voltage limit of the yellow LED light is the same as that of the red LED light, which is 6V.
    B.The minimum voltage limit of Six pcs LEDs group:
        1.White LEDs: According to the minimum driving voltage: 6*3.0=18V, if LED light’s power supply is 18V, this LED light can’t be added a current-limit resistor. If LED lights from other groups are broken, that will cause the current crease on this group LED light, which results in LED burning. But if addingcurrent-limitresistor on this group LED light, it will be lower than the minimum LED driving voltage, and it will affect the luminous intensity and glowing effect of the LED lamp. Therefore, the lowest voltage limit of white LED lights is 24V.
        2.Red LEDs: According to the minimum driving voltage: 6*1.8V=10.8V, based on the common power supply specification, 12V is fine. As 12V-10.8V=1.2V, we can also add 60 ohms current-limit resistor. So the minimum voltage limit of red LED light is 12V. 
        3.Blue LEDs: The minimum voltage limit of the blue LED light is the same as that of the red LED, which is 24V.
        4.Green LEDs: According to the minimum driving voltage: 6*2.9V=17.4V, then based on the common power supply voltage specification, 18V is fine. 18V-17.4V=0.6V, we can also add 30 ohms current-limit resistor. So the minimum limiting voltage of the green LED light is 18V.
        5.Yellow LEDs: The minimum limiting voltage of the yellow LED light is the same as that of the red LED light, which is 12V.