RGB LED selection for battery powered device

[ramonmaruko]

I am not sure if this board or the "Beginners" board is the correct place to post this thread, since I am a beginner.

I am designing a keyboard for personal use. This will be a wireless split keyboard with per-key backlight RGB LED. I will be using the LP5868 matrix driver.

These are the design specifications I am looking for for the LED:

• If = 3mA
• Will work at 3.3v
• "Reverse mount"/bottom entry

Since this will be powered by a battery, I want to limit the maximum current consumption per LED channel to 3 mA (the minimum allowed by LP5868). I also want to avoid adding a 5v rail and just want to use
the available 3.3v rail on my board.

I have narrowed down my options to:

• T36K3BGR-05D000121U1930
• APF3236LSEEZGKQBKC

The APF3236LSEEZGKQBKC is not really reverse mount, but I am thinking of drilling a hole in the PCB and soldering it upside down. I am not sure of the implication sit will have on thermal dissipation.
The T36K3BGR-05D000121U1930 meets almost all of the criteria I want, except it was tested at 5mA; but I guess that can work at 3mA. The specifications for T36K3BGR-05D000121U1930 is also suspicious.
It listed a minimum luminous intensity @ 5mA of 900 mcd for RGB, while the APF3236LSEEZGKQBKC @ 2 mA can only output 6/20/4 typ. mcd. So I am hesitant on using the Harvatek part.

Another option that I am looking at is using standard power RGB LEDs like XZMDKCBDDG45S-9, but
the max Vf for the blue and green channels also exceed 3.3v. However looking at the charts in the datasheet, running them at If = 3mA, they should only have a Vf of around 2.7v... if I understood
the charts correctly.



So my questions are:

1. Should I trust the datasheets of T36K3BGR-05D000121U1930 and Harvatek in general? I also see that they had been sued before y other companies for patent infringing...
2. Is it alright to use "standard" (i.e. not advertised as low power/low vf) LEDs provided they have a Vf < 3.3v @ If = 3 mA?
3. How much lumens is needed for a per key backlight RGB led for a computer keyboard? Ideally, it should be visible even with ambient light, but should not be annoying to my while I use it.