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mm5450-led-display-driver

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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!

MM5450 - 35-Output LED Display Driver

Details

  • Location: Cabinet-3, Bin 43, Section A
  • Category: LED Drivers
  • Brand: Microchip Technology (formerly Micrel)
  • Part Number: MM5450
  • Package: 40-DIP / 44-PLCC
  • Quantity: 5
  • Status: Available
  • Price Range: $8.00-15.00
  • Datasheet: MM5450/5451 Datasheet
  • Product URL: Microchip Product Page

Description

The MM5450 is a 35-output LED display driver designed to control large LED arrays and multiplexed displays with minimal microcontroller I/O requirements. Using a simple serial interface, it can drive up to 35 individual LEDs directly, making it ideal for dot matrix displays, bar graphs, seven-segment displays, and custom LED arrays. The device features built-in current regulation, over-voltage protection, and CMOS technology for reliable operation in display applications.

Specifications

Electrical Characteristics

  • Supply Voltage: 4.5V to 13.2V
  • Output Current: 25mA per output (typical)
  • Total Outputs: 35 individual LED drivers
  • Input Logic Levels: CMOS compatible
  • Serial Interface: Clock and data inputs
  • Output Voltage: Up to VDD - 1.5V
  • Quiescent Current: Low power CMOS consumption
  • Operating Temperature: 0°C to +70°C (commercial)

Physical Characteristics

  • Package Options: 40-pin DIP, 44-pin PLCC
  • DIP Dimensions: 0.600” (15.24mm) width
  • Pin Pitch: 0.100” (2.54mm) for DIP
  • Lead Material: Standard DIP/PLCC leads

Key Features

  • 35 independent LED output drivers
  • Serial data interface for easy control
  • Built-in current regulation for each output
  • Over-voltage protection with internal Schottky diodes
  • CMOS technology for low power consumption
  • Wide supply voltage range
  • Direct LED drive capability
  • Minimal external components required

Pinout Diagram (40-Pin DIP)

    MM5450 40-Pin DIP
    ┌─────────────────────┐
OUT1│1                 40│ VDD
OUT2│2                 39│ OUT35
OUT3│3                 38│ OUT34
OUT4│4                 37│ OUT33
OUT5│5                 36│ OUT32
OUT6│6                 35│ OUT31
OUT7│7                 34│ OUT30
OUT8│8                 33│ OUT29
OUT9│9                 32│ OUT28
OUT10│10               31│ OUT27
OUT11│11               30│ OUT26
OUT12│12               29│ OUT25
OUT13│13               28│ OUT24
OUT14│14               27│ OUT23
OUT15│15               26│ OUT22
OUT16│16               25│ OUT21
OUT17│17               24│ OUT20
OUT18│18               23│ OUT19
CLK │19               22│ DATA
VSS │20               21│ BRIGHTNESS
    └─────────────────────┘

Pin Descriptions

PinNameDescription
1-18, 22-39OUT1-OUT35LED output drivers
19CLKSerial clock input
20VSSGround (negative supply)
21BRIGHTNESSBrightness control input
22DATASerial data input
40VDDPositive power supply

Applications

Common use cases for the MM5450:

  • LED dot matrix displays
  • Large seven-segment displays
  • LED bar graphs and level meters
  • Custom LED arrays and patterns
  • Alphanumeric LED displays
  • Status indicator panels
  • Decorative LED lighting
  • Industrial control panel displays

Circuit Examples

Basic LED Matrix Interface

Microcontroller:
Digital Pin 8 ---- CLK (Pin 19) - Serial Clock
Digital Pin 9 ---- DATA (Pin 22) - Serial Data
VDD (Pin 40) ---- +5V Power Supply
VSS (Pin 20) ---- Ground
BRIGHTNESS (Pin 21) ---- Brightness Control (PWM or analog)

Each Output (OUT1-OUT35) ---- Current Limiting Resistor ---- LED ---- Ground

7-Segment Display Driver

OUT1-OUT7 ---- Segments A-G of first digit
OUT8-OUT14 ---- Segments A-G of second digit
OUT15-OUT21 ---- Segments A-G of third digit
OUT22-OUT28 ---- Segments A-G of fourth digit
OUT29-OUT35 ---- Additional segments or decimal points

LED Bar Graph

OUT1 ---- LED1 (lowest level)
OUT2 ---- LED2
...
OUT35 ---- LED35 (highest level)
Each LED with appropriate current limiting resistor

Programming Examples

Arduino Basic Control

#define CLK_PIN 8
#define DATA_PIN 9
#define BRIGHTNESS_PIN 10
 
void setup() {
  pinMode(CLK_PIN, OUTPUT);
  pinMode(DATA_PIN, OUTPUT);
  pinMode(BRIGHTNESS_PIN, OUTPUT);
 
  // Set brightness (PWM)
  analogWrite(BRIGHTNESS_PIN, 128); // 50% brightness
}
 
void sendData(uint64_t data) {
  // MM5450 requires 36 bits (start bit + 35 data bits)
  uint64_t dataToSend = (1ULL << 35) | data; // Add start bit
 
  for(int i = 35; i >= 0; i--) {
    digitalWrite(CLK_PIN, LOW);
    digitalWrite(DATA_PIN, (dataToSend >> i) & 1);
    delayMicroseconds(1);
    digitalWrite(CLK_PIN, HIGH);
    delayMicroseconds(1);
  }
 
  digitalWrite(CLK_PIN, LOW);
  digitalWrite(DATA_PIN, LOW);
}
 
void loop() {
  // Light up LEDs in sequence
  for(int i = 0; i < 35; i++) {
    sendData(1ULL << i);
    delay(100);
  }
 
  // All LEDs on
  sendData(0x7FFFFFFFFULL); // All 35 bits set
  delay(1000);
 
  // All LEDs off
  sendData(0);
  delay(1000);
}

LED Bar Graph Display

void displayBarGraph(int level) {
  // level: 0-35 (number of LEDs to light up)
  uint64_t pattern = 0;
 
  for(int i = 0; i < level && i < 35; i++) {
    pattern |= (1ULL << i);
  }
 
  sendData(pattern);
}
 
void loop() {
  // Simulate varying signal level
  for(int level = 0; level <= 35; level++) {
    displayBarGraph(level);
    delay(50);
  }
 
  for(int level = 35; level >= 0; level--) {
    displayBarGraph(level);
    delay(50);
  }
}

7-Segment Display

// 7-segment patterns (A-G segments)
uint8_t digitPatterns[10] = {
  0b0111111, // 0
  0b0000110, // 1
  0b1011011, // 2
  0b1001111, // 3
  0b1100110, // 4
  0b1101101, // 5
  0b1111101, // 6
  0b0000111, // 7
  0b1111111, // 8
  0b1101111  // 9
};
 
void displayNumber(int number) {
  uint64_t pattern = 0;
  int digit = 0;
 
  // Extract digits and create pattern
  do {
    int d = number % 10;
    number /= 10;
 
    // Place digit pattern in appropriate position
    pattern |= ((uint64_t)digitPatterns[d]) << (digit * 7);
    digit++;
  } while(number > 0 && digit < 5); // Max 5 digits
 
  sendData(pattern);
}

Technical Notes

Important considerations for the MM5450:

  • Serial Protocol: Requires 36-bit data frame (start bit + 35 data bits)
  • Current Limiting: Use appropriate resistors for LED current limiting
  • Power Supply: Ensure adequate current capability for all active LEDs
  • Brightness Control: Use PWM on BRIGHTNESS pin for dimming
  • Timing: Observe minimum clock pulse widths for reliable operation
  • Heat Dissipation: Consider thermal management with many active outputs

Design Considerations

LED Current Management

  • Current Limiting: Calculate resistor values for desired LED current
  • Power Dissipation: Monitor total power consumption with multiple LEDs
  • Supply Current: Ensure power supply can handle peak current demands
  • Thermal Design: Provide adequate heat sinking for high current applications

Display Design

  • Multiplexing: Can be used with multiplexed displays for even larger arrays
  • Brightness Control: Implement PWM brightness control for user adjustment
  • Pattern Storage: Store display patterns in microcontroller memory
  • Update Rate: Balance update frequency with visual persistence

Tags

led-driver, display-driver, serial-interface, 35-output, microchip-technology cabinet-3 bin-43 status-available

Notes

The MM5450 is a classic and versatile LED display driver that has been used in countless display applications for decades. Having 5 of these ICs provides excellent capability for building large LED displays, dot matrix arrays, and multi-digit seven-segment displays. The serial interface makes it easy to control from any microcontroller with just two I/O pins, while the 35 outputs provide substantial LED driving capability. The built-in current regulation and over-voltage protection make it reliable and easy to use. This IC is perfect for projects requiring many LED outputs without consuming numerous microcontroller pins, making it ideal for display applications, status indicators, and decorative lighting projects.

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