MAX7219 & MAX7221 8-Digit LED Drivers Analog Devices MAX7219 and MAX7221 8-Digit LED Display Drivers are compact, serial input/output common-cathode display drivers that interface microprocessors to 7-segment numeric LED displays of up to 8 digits, to bar-graph displays, or to 64 individual LEDs. Included on-chip are a BCD code-B decoder, multiplex scan circuitry, segment and digit drivers, and an 8x8 static RAM that stores each digit. Only one external resistor is required to set the segment current for all LEDs.