MAX7219CNG+

The MAX7219 is an integrated controller for 8-digit 7-segment LED displays with a common cathode. It can also control bar-graph displays and individual LEDs (up to 64). It is equipped with: segment drivers and 1-digit display drivers, control registers for display operation, BCD code B decoder, display multiplexing circuits (only one display is lit at a time for a set period), and a dual-port 8x8 SRAM memory that stores the data to be displayed. The only required external component is the RSET resistor, which sets the maximum segment current. Data can be displayed using BCD code (characters 0,1,...,9, –, E, H, L, P, blank) or 7-segment code. The brightness can be adjusted at the hardware level by connecting the appropriate RSET resistor, or at the software level by writing the appropriate value to the control register. A 3-wire serial interface is used for connection to the external world. The number of displayed characters can be increased by cascading the ICs.

Selected Parameters:

- Clock frequency of the interface: 10MHz;
- Multiplexing frequency (for 8 displayed characters): 800Hz;
- Segment current: -40mA (for RSET = 9.53kΩ);
- Current consumption:
Normal operation mode (all segments on): 330mA;
Shutdown mode (display off): 150µA;
- Operating temperature: 0÷70°C;
- Supply voltage: 4.0÷5.5V;

Control Registers of the IC:

Shutdown: selection between normal operation mode and shutdown mode
Mode: selection between BCD code and 7-segment code display
Intensity: selection of brightness intensity
Scan-Limit: selection of displays (multiplexing)
Display-Test: selection between normal mode and test mode