SunFounder PCA9685 16 Channel 12 bit PWM Servo Driver for Arduino and Raspberry Pi

Contain an I2C-controlled PWM driver with a built-in clock. It means, unlike the TLC5940 family, you do not need to continuously send it signals tying up your microcontroller; it's completely free running 5V compliant, which means you can control it from a 3.3V microcontroller (this is good when you want to control white or blue LEDs with 3.4+ forward voltages) Support using only two pins to control 16 free-running PWM outputs – you can even chain up 62 breakouts to control up to 992 PWM outputs 3 pin connectors in groups of 4, so you can plug in 16 servos at one time (Servo plugs are slightly wider than 0.1" so you can only stack 4 next to each other on 0.1" header 12-bit resolution for each output - for servos, that means about 4us resolution at 60Hz update rate