How to Use 4081 Quad And Gates: Examples, Pinouts, and Specs

The 4081B is a Quad 2-input AND Gate integrated circuit (IC) from Texas Instruments. It contains four independent gates, each of which performs the logical AND function. The 4081B is a fundamental component in digital electronics, used in various applications such as logic control systems, computer logic, and other circuits where a logical AND operation is required.

• Digital logic circuits
• Signal gating
• Logic level conversion
• Function generators
• Alarm systems
• Embedded systems

• Supply Voltage (Vcc): 3V to 18V
• High-Level Input Voltage (VIH): Minimum 3.15V (for Vcc = 5V)
• Low-Level Input Voltage (VIL): Maximum 1.35V (for Vcc = 5V)
• High-Level Output Voltage (VOH): Minimum 4.6V (for Vcc = 5V, IO = -4.2mA)
• Low-Level Output Voltage (VOL): Maximum 0.4V (for Vcc = 5V, IO = 4.2mA)
• Input Current (II): ±1µA at Vcc = 18V
• Operating Temperature Range: -55°C to +125°C

1. Connect the Vcc pin (14) to the positive supply voltage within the specified range (3V to 18V).
2. Connect the GND pin (7) to the ground of the circuit.
3. Apply the input signals to the A and B inputs of the desired gate(s).
4. The output Y of each gate will be high only when both A and B inputs are high.

• Ensure that the supply voltage does not exceed the maximum rating to prevent damage.
• Inputs should not be left floating; they should be connected to a definite high or low logic level.
• Use pull-up or pull-down resistors if necessary to maintain a stable input logic level when switches or open-collector outputs are used.
• Decoupling capacitors (typically 0.1µF) should be placed close to the Vcc pin to filter out noise and provide a stable supply voltage.

• Outputs not behaving as expected: Ensure that all inputs are at valid logic levels and that the supply voltage is within the specified range.
• IC getting hot: Check for short circuits or an over-voltage condition.

• Verify the supply voltage and input levels with a multimeter.
• Check the connections to ensure that they are secure and correct.
• Replace the IC if it is suspected to be faulty.

Q: Can I use the 4081B IC with a 5V supply? A: Yes, the 4081B can operate with a supply voltage as low as 3V and up to 18V.

Q: What happens if one of the inputs is left unconnected? A: An unconnected input can pick up noise and cause unpredictable output. Always connect unused inputs to a known logic level.

Q: Is the 4081B compatible with TTL logic levels? A: The 4081B is a CMOS device and has different voltage levels compared to TTL. However, it can often be interfaced with TTL logic with proper level shifting.

The following example demonstrates how to use the 4081B AND gate with an Arduino UNO. The code reads two digital inputs and sends the result of the AND operation to an LED.

// Define the input and output pins
const int inputPinA = 2;
const int inputPinB = 3;
const int outputPin = 13; // LED on Arduino

void setup() {
  // Configure the input and output pins
  pinMode(inputPinA, INPUT);
  pinMode(inputPinB, INPUT);
  pinMode(outputPin, OUTPUT);
}

void loop() {
  // Read the input values
  bool inputA = digitalRead(inputPinA);
  bool inputB = digitalRead(inputPinB);

  // Perform the AND operation and set the output
  bool output = inputA && inputB;
  digitalWrite(outputPin, output);

  // Delay for debounce
  delay(50);
}

Remember to connect the Arduino pins to the corresponding inputs of the 4081B AND gate and the output to the LED with a suitable current-limiting resistor.