Data Sheet

6/30/2015 LightemittingDiodes(LEDs)learn.sparkfun.com
https://learn.sparkfun.com/tutorials/lightemittingdiodesleds?_ga=1.43468261.1900427809.1434378181 3/13
ThepositivesideoftheLEDiscalledthe“anode”andismarkedbyhavingalonger“lead,”orleg.
Theother,negativesideoftheLEDiscalledthe“cathode.”Currentflowsfromtheanodetothe
cathodeandnevertheoppositedirection.AreversedLEDcankeepanentirecircuitfromoperating
properlybyblockingcurrentflow.Sodon’tfreakoutifaddinganLEDbreaksyourcircuit.Tryflippingit
around.
2)MoarCurrentEqualsMoarLight
ThebrightnessofanLEDisdirectlydependentonhowmuchcurrentitdraws.Thatmeanstwothings.
ThefirstbeingthatsuperbrightLEDsdrainbatteriesmorequickly,becausetheextrabrightness
comesfromtheextrapowerbeingused.ThesecondisthatyoucancontrolthebrightnessofanLED
bycontrollingtheamountofcurrentacrossit.But,settingthemoodisn’ttheonlyreasontocutback
yourcurrent.
3)ThereisSuchaThingasTooMuchPower
IfyouconnectanLEDdirectlytoacurrentsourceitwilltrytodissipateasmuchpowerasit’sallowed
todraw,and,likethetragicheroesofolde,itwilldestroyitself.That’swhyit’simportanttolimitthe
amountofcurrentflowingacrosstheLED.
Forthis,weemployresistors.ResistorslimittheflowofelectronsinthecircuitandprotecttheLED
fromtryingtodrawtoomuchcurrent.Don’tworry,itonlytakesalittlebasicmathtodeterminethe
bestresistorvaluetouse.Youcanfindoutallaboutitinourresistortutorial!
Don’tletallofthismathscareyou,it’sactuallyprettyhardtomessthingsuptoobadly.Inthenext
section,we’llgooverhowtomakeanLEDcircuitwithoutgettingyourcalculator.
LEDsWithoutMath
Beforewetalkabouthowtoreadadatasheet,let’shookupsomeLEDs.Afterall,thisisanLED
tutorial,notareadingtutorial.