An LED display driver is an IC (integrated circuit) that provides the circuitry necessary in order to interface most common microprocessors or digital systems to an LED display. Included on an LED display driver may be a static display memory, segment decoders, multiplex scan circuitry and high current segment and digit drivers for displays.

Finally, you can cascade more than one device to control more digits. Just run a connection from the data out pin on the first device to the data pin of the second one, and all the clock and enable lines together. However trying to display the alphabet using 7-segment displays is somewhat passé. Instead, get some 16-segment LED modules or an LCD.