7408 Quad 2-Input AND Gate Technical Summary

Overview

The 7408 is a quad 2-input AND gate integrated circuit belonging to the 7400 series of logic devices. It contains four independent AND gates, each performing the logical AND function. The 7408 is widely used in digital logic circuits where logical conjunction operations are required. This device operates with standard TTL (Transistor-Transistor Logic) voltage levels and is compatible with other TTL family components.

The 7408 is characterized by its robust design, reliable operation, and ease of integration into various digital systems. It is available in multiple package options, including DIP (Dual In-line Package) and SOIC (Small Outline Integrated Circuit), making it suitable for both through-hole and surface-mount applications.

Features

• Quad 2-input AND gates in a single package
• Standard TTL switching voltages
• Fully compatible with most TTL logic families
• Wide operating voltage range: 4.75V to 5.25V
• Typical propagation delay: 9ns
• Low power consumption: 10mW typical per gate
• High noise immunity characteristic of TTL devices
• Available in multiple package options
• Operating temperature range: 0°C to 70°C (commercial grade)

Applications

The 7408 finds application in numerous digital systems and circuits, including:

• Digital logic circuits
• Arithmetic logic units (ALUs)
• Data processing systems
• Control systems
• Signal gating and routing
• Address decoding
• Clock synchronization circuits
• General purpose logic implementations
• Educational electronics projects

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_CC): -0.5V to +7V
• DC Input Voltage (V_I): -0.5V to V_CC + 0.5V
• DC Output Voltage (V_O): -0.5V to V_CC + 0.5V
• DC Input Diode Current (I_IK): ±20mA
• DC Output Diode Current (I_OK): ±20mA
• DC Output Source/Sink Current (I_O): ±25mA
• DC V_CC/GND Current (I_CC): ±50mA
• Storage Temperature Range: -65°C to +150°C

Recommended Operating Conditions

• Supply Voltage (V_CC): 4.75V to 5.25V
• Input High Voltage (V_IH): 2V min
• Input Low Voltage (V_IL): 0.8V max
• Output High Current (I_OH): -400μA
• Output Low Current (I_OL): 16mA
• Operating Temperature Range: 0°C to 70°C

Switching Characteristics (at V_CC = 5V, T_A = 25°C)

• Propagation Delay (t_PLH, t_PHL): 9ns typical, 15ns max
• Output Transition Time (t_TLH, t_THL): 10ns typical, 15ns max
• Input Capacitance: 3pF typical
• Power Dissipation per Gate: 10mW typical

Pin Configuration and Truth Table

Pin Description

• Pin 1, 4, 9, 12: 1A to 4A (Data Inputs for gates 1 through 4)
• Pin 2, 5, 10, 13: 1B to 4B (Data Inputs for gates 1 through 4)
• Pin 3, 6, 8, 11: 1Y to 4Y (Data Outputs for gates 1 through 4)
• Pin 7: GND (Ground, 0V reference)
• Pin 14: V_CC (Positive Supply Voltage, +5V nominal)

Truth Table

For each individual AND gate:

Where: L = Low level (0V), H = High level (V_CC)

Package Information

The 7408 is available in several package options, with the 14-pin DIP being the most common:

• PDIP-14 (Plastic Dual In-line Package)
  • Body width: 7.62mm
  • Pin spacing: 2.54mm
  • Overall length: 19.3mm
  • Lead material: Copper alloy
• SOIC-14 (Small Outline Integrated Circuit)
  • Body width: 3.9mm
  • Pin spacing: 1.27mm
  • Overall length: 8.65mm
  • Lead material: Copper alloy
• TSSOP-14 (Thin Shrink Small Outline Package)
  • Body width: 4.4mm
  • Pin spacing: 0.65mm
  • Overall length: 5mm
  • Lead material: Copper alloy

Design Considerations

When implementing the 7408 in circuit designs, consider the following:

• Ensure proper power supply decoupling with a 0.1μF ceramic capacitor placed close to the V_CC pin
• Unused inputs should be tied to either V_CC or GND through a resistor (1kΩ recommended)
• Outputs should not be connected directly together
• For high-speed applications, minimize trace lengths to reduce parasitic capacitance
• Observe maximum fan-out limitations (10 standard TTL loads