The MAX7219/MAX7221 are compact, serial input/out- put common-cathode display drivers that interface microprocessors (μPs) to 7-segment numeric LED dis- plays of up to 8 digits, bar-graph displays, or 64 indi- vidual 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 seg- ment current for all LEDs. The MAX7221 is compatible with SPITM, QSPITM, and MICROWIRETM, and has slew- rate-limited segment drivers to reduce EMI.
A convenient 4-wire serial interface connects to all common μPs. Individual digits may be addressed and updated without rewriting the entire display. The MAX7219/MAX7221 also allow the user to select code- B decoding or no-decode for each digit.
The devices include a 150μA low-power shutdown mode, analog and digital brightness control, a scan- limit register that allows the user to display from 1 to 8 digits, and a test mode that forces all LEDs on.
For applications requiring 3V operation or segment blinking, refer to the MAX6951 data sheet.