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max7219cng-led-matrix-driver

4 min read

Important Note

This entire repo was AI created - including all of the data within. The intent was to A) help me with my personal electronics inventory; and B) see how I could use AI to make that process a bit easier. DO NOT TRUST!

MAX7219CNG - LED Matrix/Digit Display Driver

Details

  • Location: Cabinet-3, Bin 39, Section C
  • Category: Display Drivers
  • Brand: Adafruit (Maxim Integrated IC)
  • Part Number: MAX7219CNG
  • Package: 24-DIP
  • Quantity: 20
  • Status: Available
  • Price Range: 11.66 (10-99), $10.36 (100+)
  • Datasheet: MAX7219 Datasheet
  • Product URL: https://www.adafruit.com/product/453

Description

The MAX7219 is a serially interfaced, 8-digit LED display driver that can control either an 8x8 LED matrix or up to 8 seven-segment displays (64 LEDs total). This IC handles all the multiplexing, current regulation, and refresh duties automatically, requiring only a simple 4-pin SPI interface for control. It eliminates the need for external current-limiting resistors for each LED segment and provides built-in BCD code-B decoder, multiplex scan circuitry, segment and digit drivers, and an 8x8 static RAM for storing each digit.

Specifications

Electrical Characteristics

  • Operating Voltage: 4.0V ~ 5.5V
  • Supply Current: 330mA maximum (all segments on)
  • Interface: 4-wire SPI (CLK, CS, DIN, DOUT)
  • Output Current: Up to 40mA per segment
  • Scan Rate: 800Hz typical
  • Power Dissipation: 665mW maximum

Physical Characteristics

  • Package: 24-pin DIP (Dual In-line Package)
  • Dimensions: 0.600” (15.24mm) width
  • Pin Pitch: 0.100” (2.54mm)
  • Operating Temperature: 0°C to +70°C

Key Features

  • Drives 8x8 LED matrix or 8-digit 7-segment displays
  • SPI-compatible serial interface
  • Individual LED segment control
  • Built-in BCD code-B decoder
  • 16-step digital brightness control
  • Display blanking and shutdown modes
  • No external current-limiting resistors needed per segment

Image

MAX7219CNG LED Matrix Driver

Pinout Diagram

    MAX7219 24-Pin DIP
    ┌─────────────────┐
DIN │1              24│ VCC
DIG0│2              23│ ISET
DIG4│3              22│ V+
GND │4              21│ SEG DP
DIG6│5              20│ SEG A
DIG2│6              19│ SEG F
DIG3│7              18│ GND
DIG7│8              17│ SEG B
GND │9              16│ SEG G
DIG5│10             15│ DOUT
DIG1│11             14│ SEG C
LOAD│12             13│ SEG E
    └─────────────────┘

Pin Descriptions

PinNameDescription
1DINSerial Data Input
2-11DIG0-DIG7Digit Drive Lines (cathodes for common-cathode displays)
12LOADLoad Data (Chip Select)
13-20SEG E,C,G,B,F,A,DPSegment Drive Lines (anodes)
21V+LED Supply Voltage
22ISETCurrent Set (connect resistor to GND)
23DOUTSerial Data Output (for daisy chaining)
24VCCLogic Supply Voltage

Applications

Common use cases for the MAX7219:

  • 8x8 LED matrix displays for graphics and text
  • Multi-digit 7-segment numeric displays
  • Digital clocks and counters
  • Status indicators and scoreboards
  • Scrolling text displays
  • Arduino and microcontroller projects
  • Educational electronics projects
  • Retro gaming displays

Circuit Examples

Basic 8x8 LED Matrix Connection

Arduino/MCU    MAX7219
VCC     ----   VCC (Pin 24)
GND     ----   GND (Pins 4, 9, 18)
D13     ----   CLK (connect to DIN via shift register logic)
D11     ----   DIN (Pin 1)
D10     ----   CS/LOAD (Pin 12)

ISET (Pin 22) ---- 10kΩ resistor ---- GND
V+ (Pin 21) ------ VCC (LED supply)

Current Setting Resistor

ISET Resistor Value = 31,500 / (desired segment current in mA)
For 20mA: R = 31,500 / 20 = 1.575kΩ (use 1.5kΩ)
For 40mA: R = 31,500 / 40 = 787.5Ω (use 820Ω)

Programming Examples

Arduino Example

#include <LedControl.h>
 
// DIN, CLK, LOAD, number of devices
LedControl lc = LedControl(12, 11, 10, 1);
 
void setup() {
  lc.shutdown(0, false);  // Wake up MAX7219
  lc.setIntensity(0, 8);  // Set brightness (0-15)
  lc.clearDisplay(0);     // Clear display
}
 
void loop() {
  // Set LED at row 0, column 0
  lc.setLed(0, 0, 0, true);
  delay(1000);
  lc.setLed(0, 0, 0, false);
  delay(1000);
}

CircuitPython Example

import board
import digitalio
from adafruit_max7219 import matrices
 
spi = board.SPI()
cs = digitalio.DigitalInOut(board.D5)
matrix = matrices.Matrix8x8(spi, cs)
 
# Set pixel at (0,0)
matrix.pixel(0, 0, 1)
matrix.show()

Technical Notes

Important considerations for the MAX7219:

  • Current Setting: Use appropriate ISET resistor to set segment current
  • Power Supply: Separate V+ supply may be needed for high-current applications
  • Daisy Chaining: Multiple MAX7219s can be chained using DOUT to DIN
  • Decoupling: Use 0.1µF capacitor between VCC and GND
  • Heat Dissipation: Consider heat sinking for high-current applications

Tags

display-driver, led-matrix, max7219, spi, multiplexing, adafruit, maxim cabinet-3 bin-39 status-available

Notes

The MAX7219 is an essential component for anyone working with LED matrix displays or multi-digit 7-segment displays. Having 20 of these ICs provides excellent flexibility for building multiple display projects or large multi-matrix installations. The SPI interface makes it easy to integrate with Arduino, Raspberry Pi, and other microcontrollers. The built-in multiplexing and current regulation eliminate much of the complexity typically associated with driving LED matrices, making it perfect for both beginners and advanced projects. These ICs can be daisy-chained to create larger displays, and the digital brightness control allows for professional-looking results.

Graph View

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