[ Copying the list again. ] Allen Chang wrote: > LED1501==>LED Ultra Bright Amber/Blue ??p=609/468nm SMT 3.2*1.0*1.5mm > 3PIN HT-210UD/NB HARVATEK > LED1502 ==>LED Ultra Bright Red ?????=636nm SMT 3.2*1.5*1.0mm 2PIN > HT-110USD5 HARVATEK
Thanks a lot ! I put the data sheets into our internal document repository. I examined this because I found that the power button LEDs seemed a bit dim. Here's what I found: All three LEDs are being supplied through 220 Ohm from 3.3V. If we look at the typical forward voltages, we get these currents: red: (3.3V-1.9V)/220R = 6.4mA amber: (3.3V-1.9V)/220R = 6.4mA blue: (3.3V-3.3V)/220R = 0mA Okay, that's obviously not the right result for blue. We're too close to the non-linear part of to curve there. Next try: if I draw a line for (3.3V-x)/220R into the Vf vs. If diagrams, I get roughly the following intersections: amber (UD): 1.78V / 7mA blue (NB): 2.9V / 2.5mA Taking this to the intensity vs. current chart, and multiplying with the minimum and typical luminous intensity, I get amber: 7mA -> 25% 14-30mcd blue: 2.5mA -> 15% 5.4-9mcd Interestingly, on my GTA02v5, amber looks less bright than blue. Red, which should be quite similar to amber, looks fine. We could safely reduce R1561, R1563, and even R1562 to 100 Ohm, which would make the LEDs roughly twice as bright (and double their current consumption, which, in the case of GTA02v6, would be of course still far below GTA02v5's). Do we care to make such a change ? - Werner
