I have been thinking about why the led turns of when the tlc5940 tries to turn it on.
My theory (or call it a bump of this post
The tlc5940 works as a current source (actually a current sink). Assuming I have a resistor so it will sink 20mA.
When the tlc5940 turns the led on the current can only pass though the resistor (due to the led blocking the current)
This will cause a voltage drop over the resistor.
If the voltage drop is big enough there is not enough tension over the led to allow a current.
Assuming a voltage drop of 1.5 volt over the led the voltage drop over the resistor needs to be more than (5-1.5) 3.5
In other words the resistor must have at least (r=u/i 3.5/0.02) 175 ohm
The nearest I have is 180 ohm but I think this is to close so I would go for 220 for the blue led.
Now I can calculate/measure the blue current and calculate the resistors for reg and green.
Does this seem correct?