mjkzz:
Most of strips are voltage based, not current based, I mean, they have resistor built-in to limit the current. TLC5940 is a constant current IC so I am not sure you really need it,
We have been through that at the start of the thread. He is not using the constant current bit of the chip just the PWM bit. This chip gives 16 PWM channels which is more than you can get on the Arduino. This is why the power dissipation is so low, because the constant current part is not kicking in.
My bad 
Hello
thanks for all the input.
so it seems i can proceed with the project.
i will solder cables to the strips and hook them up in the next days.
thanks again for the help
Hi,
Are you opposed to using a SoftPWM library for your project? The following Library is great:
I used it to complete a 6 x 10w RGB Lamp Cluster project controlled by 1 Atmega 328p that SoftPWMs 18 pins/channels at 110Hz. The chip which is running at 16mhz has no performance issues and accurately handles IR command input on another pin, and does the required calculations to support dynamic lighting sequences/modes without a stutter. Going this route would reduce your solutions hardware footprint alot, and you won't have to deal with the issue that comes with using the TLC5940 /inverted PWM: the lights won't fully dim to off... They'll always be lit just a very little...