The MAX7219/MAX7221 are compact, serial input/output common-cathode display drivers that interface microprocessors (µPs) to 7-segment numeric LED displays of up to 8 digits, bar-graph displays, or 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. The MAX7221 is compatible with SPI™, QSPI™, and MICROWIRE™, 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.
The MAX7219 and MAX7221 are compact serial input/output common‑cathode display drivers that interface microprocessors to up to eight 7‑segment numeric LED digits, bar‑graph displays, or 64 individual LEDs. The devices integrate a BCD code‑B decoder, multiplex scan circuitry, segment and digit drivers, and an 8×8 static RAM for digit storage.
Key features include a 4‑wire SPI/QSPI/MICROWIRE compatible interface, low‑power shutdown mode, analog and digital brightness control via an external resistor (RSET) and an intensity register, and a scan‑limit register that selects the number of active digits. The MAX7221 adds slew‑rate‑limited segment drivers to reduce EMI. Typical applications are LED numeric displays, bar‑graph indicators, and multiplexed LED matrices.
| Operating Supply Current | 150 µA |
|---|---|
| Shutdown Supply Current | -10 µA |
| Maximum Segment Current | 40 mA |
| Temperature Range (MAX7219) | 0 °C to +70 °C |
| Temperature Range (MAX7221) | -40 °C to +85 °C |
Each device can control up to eight 7‑segment digits or an equivalent number of LED segments.
In shutdown mode the scan oscillator stops, segment current sources are pulled to ground, digit drivers are pulled to V+, and the display is blanked.
Brightness can be set with an external resistor (RSET) that defines the peak segment current, and also digitally via the intensity register’s pulse‑width modulation.