I have a project that powers RGB LEDs with 3v coin battery (CR2032)
so Vcc = bat = 3.0v (drops to 2.7v when nearly dead), which is below the forward voltage of Green and Blue (3.2V).
(actually I’m powering them with AVR pins, where another 0.4v drop is applied, so it’s actually 2.3~2.6v)
for Red, I just put a 120 ohm to limit the current to 10mA.
I’m using a 1 ohm resistor to limit the current, but what I wanna know what’s the actual current applied to Green and Blue?
I wanna give Green and Blue ~10mA too, to get similar brightness as Red.
it’s a really small device, and LED brightness is not really that important, so I don’t want a LED driver IC.