Adafruit 16-Channel 12-bit PWM/Servo Shield for Arduino - I2C interfaceThere's an I2C controlled PWM driver with a built in clock. That means that, unlike the TLC5940 family, you do not need to continuously send it signal tying up your microcontroller, its completely free running! It is 5V compliant, which means you can control it from a 3. 3V Arduino and still safely drive up to 6V outputs (this is good for when you want to control white or blue LEDs with 3. 4+ forward voltages) 6 address select pins so you can stack up