For driving 1 to 51/2  7 segment(and DP) common cathode displays
take a look at the Motorola MC14489. This CMOS chip directly controls
the displays with only one resistor to set current limit. It has a 3
wire SPI serial interface. Has circuitry to minimize EMI and software
dimming. Using something called BitGrabber it determines by the
number of bits written wether the code sent is control or data.
They can be cascaded. Also can be used to drive up to 25 discrete
LEDs.