lidur thanks!
yes the TLC5940 16-channel PWM chip can fit your need also exist a lib for arduino here http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1218174457
The chip support 16 PWM ch whit a resolution of 4096 each daisy chain is also possible so you can obtain more than 16 ch... the chip can be used also to contrlon RGB led using 3 ch for each