The MAX7219 is an integrated serial input/output common cathode display driver that connects a microprocessor to an 8-digit digital 7-segment LED display. It can also be connected to a bar graph display or 64 separate LEDs. It includes an on-chip B-type BCD encoder, multi-channel scan loop, segment word driver, and an 8*8 static RAM to store each data. Only one external register is used to set the segment current of each LED. A convenient four-wire serial interface can be connected to all common microprocessors. Each data can be addressed without any need to overwrite all displays when updating. The MAX7219 also allows the user to choose whether to encode or not encode each data. The entire device includes a 150μA low-power shutdown mode, analog and digital brightness control, a scan limit register that allows the user to display 1-8 bits of data, and a detection mode that allows all LEDs to illuminate.