A very useful IC, providing a low-cost way of driving RGB LEDs.  There are 3 24-bit channels per IC, so for full addressable control of a string or array of RGB LEDs you would need 1 IC per RGB LED.  WS2801 are meant to control common anode RGB LEDs.  We have both diffused and clear lens types of RGB LEDs available which work great with this controller.

WS2801 can be operated in both constant current and constant voltage modes.

They employ a 2-wire serial data connection, similar to SPI or I2C.  ICs are chained together which means whole strings can be controlled using just 2 pins on your microcontroller.  

Data is clocked in starting with the MSB of the red gray scale data and ending with the LSB of the blue gray scale data.  See picture below for details.  Plenty more information available in the datasheet.

We have found these ICs are sensitive to power supply issues, so don't forget to add a decoupling capacitor between Vcc and Gnd pins.  Although specified for a 25MHz clock we'd recommend clocking in data at <2MHz, especially for longer strings.

• Supports both constant voltage and constant current drive mode
• Programmable constant LED drive current
• Wide constant output current range 5~150mA
• Build in PWM dimming scheme for each output channel, supports free-run, especially suitable for low cost controller application
• PWM free-run capability(refresh rate(2.5KHz)
• Build in buffers to cascading data and clock to the next driver
• Output polarity reverse function
• Support hot swap
• Maximum input clock frequency 25MHz
• Power supply voltage 3.3~5.5V