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I am working with RGB LED, my question is will it burn up / get damaged

I have already chosen resistors proper for each color of R G B to draw 20mA, but running R G and B at same time draws lots of current (55mili) and shines very bright white light is this safe?

here is the picture of the schematics

http://prntscr.com/6itvec

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  • \$\begingroup\$ Can you show the led's specs? \$\endgroup\$ – Eugene Sh. Mar 19 '15 at 20:16
  • \$\begingroup\$ i cant, i cant find proper datasheet :/ \$\endgroup\$ – user3272749 Mar 21 '15 at 21:37
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The entire package probably cannot handle that current for long. You should choose the resistor values so that R+G+B current combined does not exceed the maximum rating of the package itself. Even if a single part separately can handle 20mA that does not mean the whole package can handle 20mA x 3.

There are more intelligent/efficient ways to drive LEDs than just resistors, such as constant current drivers, which may be controllable in a way that it could dynamically adjust current per LED segment based on other inputs. Like when only R is on, set R to do 20mA, but when R and G is on, set each to only 15mA to respect the package ratings etc.

Edit: If you look in the datasheet for a "maximum ratings" table, it will usually specify the total "power" that the package can handle. The power can be estimated from forward voltage drop of each LED for a particular forward current, which you can find for each of the different coloured LEDs.

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    \$\begingroup\$ Maybe it can handle it, maybe it can't - it's really a matter of guessing without a proper datasheet. \$\endgroup\$ – pjc50 Mar 19 '15 at 20:28
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    \$\begingroup\$ My answer does not state that it can or cannot, I have said that given the rating of the part, design so in the particular case that all are on, it does not exceed it. How is that an issue @pjc50 ? The OP does not need to provide the datasaheet if they can heed my advice and deal with it in their own time. If they provide a big-ass datasheet, we can specifically provide values or circuits, but that isn't the point. \$\endgroup\$ – KyranF Mar 19 '15 at 20:38
  • \$\begingroup\$ If you figure 3.5V for blue at 20 mA, that's 70 milliwatts. 2.2V for red and green at 20 mA each is 88 milliwatts for the pair, so the total power dissipated by the package will be about 160 milliwatts. Probably nothing to worry about about, but yes, it would be nice to have the max dissipation spec from the data sheet. \$\endgroup\$ – EM Fields Mar 19 '15 at 21:07
  • \$\begingroup\$ @EMFields I have a SMD Cree RGB led which uses the PLCC4 package, and it has just over 600 degrees Celsius per watt, meaning in your provided scenario (which actually closely matches my part, but not quite) the device would rise over 100 degrees above ambient. Not something you should do without good heat sinking or for long periods of time in any case. The OP should link us the full datasheet if possible \$\endgroup\$ – KyranF Mar 20 '15 at 2:27

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