Internal RGB LED - 1kOhm series resistors

Hardware
1

Hi,
im working on a PCB design around the P1 module and noticed 1k resistors in the reference design for the Photon in series to the internal RGB LED (https://docs.particle.io/datasheets/photon-(wifi)/p1-datasheet/#schematic-user-i-o). I’d like to include the same RGB LED in my design with 3.3 VCC. But I cannot get my head around the 1k resistors. Aren’t those too large, especially when looking at the datasheet of the Cree CLMVB-FKA LEDs with forward currents of 10mA(G,B) / 20mA ®? Why was this value chosen?

Thanks in advance,
Marc

2

The larger resistors are to make it less bright.

If you’ve seen the RGB LED on the Spark Core or the SparkFun Photon Red Board (actually a P1), you’ll better appreciate why it was done.

6 Likes
3

Wow. My engineer and I never checked this. We’d love for it to be far brighter!

presuming 1k would be the solution!