Ok sofar I am working with the CAT4101 1A constant current sink, for my white LEDs I set the current to 700ma and it runs quite well and use arduino to handle PWM just fine. Now since my design is using a 5v rail and all of these LED's I am using have FV of roughly 3.5 to 3.8v the driver doesn't have to waste much energy on voltage drop so it stays cool, and the led's get warm of course but not unmanageably so. Now what I am considering to reduce component count is to power 2 1 watt LED's in parallel off of one CAT4101, they both can do 350ma so the driver set to 700ma should have no problems handling both in parallel, however since the red LED has a FV of 2.2v and not 3.8 like green, will this cause a current split difference between red and green, and if so how much and how can I calculate that and correct for it?