LEDs - Different series/parallel maximum current ratings?

Thread Starter

tomk825

Joined Dec 9, 2018
11
Hi everyone,

I'm not understanding what I'm reading about this amber color LED in this data sheet (you do not need to look at the data sheet to answer my questions but it may help you if you can actually see the plots): https://www.cree.com/led-components/media/documents/XlampMLE.pdf. Be careful to look only at the amber colored data because there are several other colors available.

(1) The amber LED has a maximum current of 250 mA in parallel but only 65 mA in series. Why would an LED have different current ratings in parallel vs series? My understanding it that the LED wouldn't care what comes before it or after it in the circuit, only the current it passes and voltage it drops matter.

(2) This is very likely related to (1). On page 13, two plots are shown for Relative Luminous Flux vs. Forward Current for parallel and series applications. The plots show that the LED in parallel is at 100% relative luminous flux at about 150 mA, whereas the LED in series is at 100% relative luminous flux at just under 40 mA. Am I completely misunderstanding that this data is telling me that the LED in series will need only 40 mA to be as bright as the same LED in series at 150 mA? Whether or not I'm wrong, how do I make sense of this?

Thank you in advance.

Tom
 
Last edited:

ebeowulf17

Joined Aug 12, 2014
2,945
I believe there are multiple LEDs within each "package." Depending on how you order it, you can have those LEDs connected in series or parallel, resulting in a total package with high Vf and low current requirements or low Vf and high current for equivalent light output.

It's just like if you had 4 separate amber LEDs, you'd have a few options for series and/or parallel connections. In this case, those connections are internal to they package, so you have to decide what you want up front and order accordingly.

You can even see the four separate LEDs/package in one of the pictures:
upload_2018-12-9_21-35-57.png
 

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Thread Starter

tomk825

Joined Dec 9, 2018
11
I believe there are multiple LEDs within each "package." Depending on how you order it, you can have those LEDs connected in series or parallel, resulting in a total package with high Vf and low current requirements or low Vf and high current for equivalent light output.

It's just like if you had 4 separate amber LEDs, you'd have a few options for series and/or parallel connections. In this case, those connections are internal to they package, so you have to decide what you want up front and order accordingly.

You can even see the four separate LEDs/package in one of the pictures:
View attachment 165477
That makes perfect sense. I completely missed that. Thank you very much!
 
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