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View Full Discussion Regarding LEDs: the spec sheet for the LED controller has been posted in this thread, and I'm hoping someone can help clarify. I'm wondering what the upper limit of support in terms of forward voltage and amperage for LEDs for all keys. If I'm reading page 5 correctly, it can support up to 5.5 V. If I'm reading page 18 correctly, the current per LED is about 3.2mA (adjustable to about 3.5 mA if Rext is set to 18kOhms). Is all that correct? This would mean a red LED would be putting out about 2-10 mcd (rough range from LED part lists in this range) at 2V and 3mA. Does that sound roughly correct? And if one were to buy LEDs that required more amperage, they'd just work dimly, right? Thanks!
Spec sheet: http://www.issi.com/WW/pdf/31FL3731C.pdf
So, for the Infinity Ergodox we run the ISSI chip at 3.3 V instead of 5 V. Rext is 20 kOhms.
But yes, if you get leds that require more current they may not be as bright.
Something else to consider, USB 2.0 can only do 500 mA at most. Some laptops even have issues delivering this much.
My rough calculations though with some random LEDs: 4 chained ergodox halves were around 450 mA at full brightness.