Since the display is not a mission critical component in a system, the challenge is to be able to complete a design that minimizes the space used and the power consumed. The MAX7219 and MAX7211 accomplish this by providing a three-wire serial interface to the host processor and storing the drive data for each digit. It then sources current to each segment as needed and scans through the digits at a frequency of a few hundred hertz. Slew-rate limiting on the drivers reduces EMI in the system. Brightness can be controlled either by setting the current level or duty cycle modulating the current.