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I am trying to build my own RGB + WW + CW led with 5050 leds and to make a prototype I bought some leds.

I have RGB leds and regular white ones, the RGB are kind of dimmed at the voltage from the next datasheet, but the white ones are really bright. I use my lab power supply and when i power the white leds at 2.9V, it draws 80mA, if i use 3.2V like the datasheet suggests, it draws around 150mA and at 3.6V (maximum from datasheet), it draws about 500mA

I connect all 3 pins to have the 3 leds together. Am i doing something wrong because i can't understand why it uses this much power

Datasheet: https://www.iled.com/class/INNOVAEditor/assets/YeniDatasheets/4050-4055-4057.pdf

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  • \$\begingroup\$ DO NOT DRIVE LEDs WITH VOLTAGE! You drive them with a known current and you need to have high enough so called compliance voltage to overcome the Vf. The datasheet is really bad and does not list absolute maximum ratings, but I’m going to hazard a guess and say you have overstressed your LEDs severely. \$\endgroup\$
    – winny
    May 21, 2021 at 19:59
  • \$\begingroup\$ Thank you, i understand what i did wrong, i have some spare leds and it is just for testing so i can change my setup. I think i will use a 24v power supply to power the leds in series. I am just not sure how to calculate the resistor to keep the current at 60mA, do i need to calculate with the voltages from the datasheet or am I wrong doing that? 24v - (7 leds * 3v) = 3v, so I need a resistor to reduce the 3V? I think i am incorrect here \$\endgroup\$
    – Busteer
    May 21, 2021 at 21:25
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    \$\begingroup\$ You need to size the resistor to control the current. Using Ohm's law you can calculate the resistor value using the 3 volts and the amount of current you want, maybe 60 milliamps for each LED. Remember The same current flows through each part of a series circuit. \$\endgroup\$
    – Gil
    May 22, 2021 at 2:00

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You are meant to run LEDs at their rated current, using either a constant current power supply, or as a simpler option, put a small resistor in series to limit the current.

The voltages specified for LEDs are the range of voltages that the LED might require to achieve the rated current. Don't assume that is the correct voltage for any given LED. It will vary from batch to batch.

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  • \$\begingroup\$ Thanks, that makes a lot of sence, changing my power supply to around 60mA makes the led not warm at all and shine good. I am driving the leds via a ESP8266 with npn transistors. What should be the best way to limit current to 60mA per channel? \$\endgroup\$
    – Busteer
    May 21, 2021 at 20:37
  • \$\begingroup\$ @Busteer For high power, use a constant current driver. For moderate to low power, resistors can be used to limit current. \$\endgroup\$
    – user1850479
    May 22, 2021 at 0:48
  • \$\begingroup\$ When is it high power and when moderate to low power? I think i need a 24v power supply to have 5 leds in series, but maybe that is not a correct think to do \$\endgroup\$
    – Busteer
    May 22, 2021 at 5:25

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