Important Note
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LM324N - Quad General-Purpose Operational Amplifier

Details

Location: Cabinet-3, Bin 33, Section J
Category: Analog ICs
Brand: Texas Instruments
Part Number: LM324N
Package: 14-DIP
Quantity: 1
Status: Available
Price Range: $0.50-1.50
Datasheet: LM324 Datasheet
Product URL: TI Product Page

Description

The LM324N is a quad operational amplifier that provides four independent op-amps in a single 14-pin DIP package. Designed for single supply operation, it can operate from a single 3V to 32V supply or dual supplies of ±1.5V to ±16V. The key feature of the LM324 is its ability to operate with inputs at ground potential and output swing down to ground, making it ideal for single-supply applications. This classic general-purpose op-amp has been widely used for decades in audio, signal conditioning, and general analog circuit applications.

Specifications

Electrical Characteristics

Supply Voltage: 3V to 32V single supply, ±1.5V to ±16V dual supply
Input Offset Voltage: 3mV typical, 7mV maximum
Input Bias Current: -20nA typical, -300nA maximum
Input Common-Mode Range: 0V to (VCC - 1.5V)
Output Voltage Swing: 0V to (VCC - 1.5V)
Large Signal Voltage Gain: 100dB typical
Unity Gain Bandwidth: 1MHz typical
Slew Rate: 0.5V/µs typical

Physical Characteristics

Package: 14-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 (commercial), -40°C to +85°C (industrial)
Lead Material: Standard DIP leads

Key Features

Four independent operational amplifiers
Single supply operation capability
Input common-mode range includes ground
Output can swing to ground potential
Internally frequency compensated
Wide supply voltage range
Low power consumption

Pinout Diagram

    LM324N 14-Pin DIP
    ┌─────────────────┐
OUT1│1             14│ OUT4
IN1-│2             13│ IN4-
IN1+│3             12│ IN4+
VCC │4             11│ VCC
IN2+│5             10│ IN3+
IN2-│6              9│ IN3-
OUT2│7              8│ OUT3
    └─────────────────┘

Pin Descriptions

Pin	Name	Description
1	OUT1	Output of amplifier 1
2	IN1-	Inverting input of amplifier 1
3	IN1+	Non-inverting input of amplifier 1
4	VCC	Positive power supply
5	IN2+	Non-inverting input of amplifier 2
6	IN2-	Inverting input of amplifier 2
7	OUT2	Output of amplifier 2
8	OUT3	Output of amplifier 3
9	IN3-	Inverting input of amplifier 3
10	IN3+	Non-inverting input of amplifier 3
11	VCC	Positive power supply (connected to pin 4)
12	IN4+	Non-inverting input of amplifier 4
13	IN4-	Inverting input of amplifier 4
14	OUT4	Output of amplifier 4

Note: Ground (VSS) connection is typically made through the circuit board ground plane.

Applications

Common use cases for the LM324N:

General-purpose amplification circuits
Single-supply signal conditioning
Audio preamplifiers and mixers
Active filters and equalizers
Voltage followers and buffers
Comparator circuits (with external feedback)
Sensor signal conditioning
Battery-powered applications

Circuit Examples

Basic Non-Inverting Amplifier

Input Signal ---- IN1+ (Pin 3)
IN1- (Pin 2) ---- Feedback Network ---- OUT1 (Pin 1)
Single supply: VCC (Pin 4) to +12V, VSS to Ground
Gain = 1 + (Rf/Rg)

Quad Audio Mixer

Audio Input 1 ---- Amplifier 1 (Pins 2,3,1)
Audio Input 2 ---- Amplifier 2 (Pins 5,6,7)
Audio Input 3 ---- Amplifier 3 (Pins 9,10,8)
Audio Input 4 ---- Amplifier 4 (Pins 12,13,14)
All outputs summed through resistor network

Active Low-Pass Filter

Input ---- R1 ---- IN1+ (Pin 3)
IN1- (Pin 2) ---- R2 ---- OUT1 (Pin 1)
C1 from IN1+ to ground
C2 from IN1- to OUT1
Sallen-Key topology for smooth response

Single-Supply Voltage Follower

Input Signal ---- IN1+ (Pin 3)
IN1- (Pin 2) ---- OUT1 (Pin 1) (unity gain feedback)
VCC = +9V, VSS = Ground
Output follows input with high input impedance

Programming Examples

Arduino-Based Multi-Channel Monitor

// Monitor four analog channels through LM324 amplifiers
#define CHANNEL_1 A0
#define CHANNEL_2 A1
#define CHANNEL_3 A2
#define CHANNEL_4 A3
 
void setup() {
  Serial.begin(9600);
  analogReference(EXTERNAL); // Use external reference
}
 
void loop() {
  // Read all four channels
  int ch1 = analogRead(CHANNEL_1);
  int ch2 = analogRead(CHANNEL_2);
  int ch3 = analogRead(CHANNEL_3);
  int ch4 = analogRead(CHANNEL_4);
  
  // Convert to voltages
  float v1 = (ch1 * 5.0) / 1023.0;
  float v2 = (ch2 * 5.0) / 1023.0;
  float v3 = (ch3 * 5.0) / 1023.0;
  float v4 = (ch4 * 5.0) / 1023.0;
  
  // Display results
  Serial.print("CH1: "); Serial.print(v1, 2); Serial.print("V  ");
  Serial.print("CH2: "); Serial.print(v2, 2); Serial.print("V  ");
  Serial.print("CH3: "); Serial.print(v3, 2); Serial.print("V  ");
  Serial.print("CH4: "); Serial.print(v4, 2); Serial.println("V");
  
  delay(500);
}

Signal Quality Analyzer

void analyzeSignalQuality() {
  static int samples[4][50]; // 50 samples per channel
  static int index = 0;
  
  // Collect samples from all channels
  samples[0][index] = analogRead(CHANNEL_1);
  samples[1][index] = analogRead(CHANNEL_2);
  samples[2][index] = analogRead(CHANNEL_3);
  samples[3][index] = analogRead(CHANNEL_4);
  
  index = (index + 1) % 50;
  
  // Calculate statistics for each channel
  for(int ch = 0; ch < 4; ch++) {
    long sum = 0;
    int min_val = 1023, max_val = 0;
    
    for(int i = 0; i < 50; i++) {
      sum += samples[ch][i];
      if(samples[ch][i] < min_val) min_val = samples[ch][i];
      if(samples[ch][i] > max_val) max_val = samples[ch][i];
    }
    
    int avg = sum / 50;
    int range = max_val - min_val;
    
    Serial.print("CH"); Serial.print(ch+1);
    Serial.print(" Avg:"); Serial.print(avg);
    Serial.print(" Range:"); Serial.print(range);
    Serial.print("  ");
  }
  Serial.println();
}

Technical Notes

Important considerations for the LM324N:

Single Supply: Designed for single supply operation
Ground Sensing: Inputs can go to ground potential
Output Swing: Output can swing to within 1.5V of supply rails
Frequency Compensation: Internally compensated for unity gain
Power Supply: Use 0.1µF ceramic capacitor for decoupling
Input Protection: Consider input protection for sensitive applications

Design Considerations

Single Supply Applications

Input Biasing: May need input bias for AC-coupled signals
Output Range: Output cannot swing to negative voltages
Common Mode: Input common mode range includes ground
Coupling: Consider AC or DC coupling requirements

General Purpose Use

Gain-Bandwidth: 1MHz unity gain bandwidth suitable for audio
Slew Rate: 0.5V/µs adequate for most general applications
Offset Voltage: 3mV typical offset suitable for many applications
Temperature: Consider temperature effects in precision applications

Single Supply Advantages

The LM324’s single supply capability provides:

Simplified Power Supply: No need for negative supply rail
Ground Sensing: Can amplify signals referenced to ground
Battery Operation: Suitable for portable applications
Cost Effective: Reduces power supply complexity and cost
Wide Voltage Range: Operates from 3V to 32V

Notes

The LM324N is one of the most popular and widely used operational amplifiers in electronics, known for its versatility and single-supply capability. Having this classic IC provides excellent capability for general-purpose analog circuits, especially those requiring single-supply operation. The four independent amplifiers in one package make it ideal for multi-channel applications, audio mixing, and signal conditioning. The ability to operate with inputs at ground potential and output swing to ground makes it perfect for single-supply applications where negative supply rails are not available. This IC is an essential component for learning operational amplifier principles and building practical analog circuits.

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lm324n-quad-opamp

LM324N - Quad General-Purpose Operational Amplifier

Details

Description

Specifications

Electrical Characteristics

Physical Characteristics

Key Features

Pinout Diagram

Pin Descriptions

Applications

Circuit Examples

Basic Non-Inverting Amplifier

Quad Audio Mixer

Active Low-Pass Filter

Single-Supply Voltage Follower

Programming Examples

Arduino-Based Multi-Channel Monitor

Signal Quality Analyzer

Technical Notes

Design Considerations

Single Supply Applications

General Purpose Use

Single Supply Advantages

Tags

Notes

Graph View

Table of Contents

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