7423 Triple 3-Input NOR Gate IC

Overview

The 7427 is a monolithic triple 3-input NOR gate integrated circuit fabricated using bipolar technology. This device contains three independent NOR gates, each performing the Boolean function Y = (A + B + C)' in positive logic. The 7427 is part of the 7400 series of TTL logic chips and is widely used in digital logic design applications.

This IC features standard TTL switching voltages, high noise immunity, and fully buffered outputs. The 7427 is supplied in a 14-pin dual in-line package (DIP) and operates over the standard military temperature range of -55°C to +125°C, making it suitable for both commercial and industrial applications.

Features

• Triple 3-input NOR gates in single package
• Standard TTL power supply voltage: 4.75V to 5.25V
• Typical propagation delay: 10ns
• Low power consumption: 12mW typical per gate
• High noise immunity: 0.45V (min) noise margin
• Fully buffered outputs
• Standardized symmetrical output characteristics
• 14-pin DIP package
• Operating temperature range: -55°C to +125°C

Applications

The 7427 finds applications in various digital logic systems including:

• General purpose logic circuits
• Digital signal processing
• Data processing systems
• Computer systems
• Industrial control systems
• Instrumentation systems
• Waveform generation
• Clock distribution networks
• Error detection circuits
• Memory address decoding

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 Current (I_O): ±25mA
• DC Supply Current per Output (I_CCH/I_CCL): ±55mA
• Storage Temperature Range: -65°C to +150°C

Recommended Operating Conditions

• Supply Voltage (V_CC): 4.75V to 5.25V
• High Level Input Voltage (V_IH): 2V (min)
• Low Level Input Voltage (V_IL): 0.8V (max)
• Operating Ambient Temperature: -55°C to +125°C

DC Characteristics

• High Level Output Voltage (V_OH): 2.4V (min) at I_OH = -400μA
• Low Level Output Voltage (V_OL): 0.4V (max) at I_OL = 16mA
• Input Clamp Voltage (V_IK): -1.5V (max) at I_IK = -18mA
• High Level Input Current (I_IH): 40μA (max) at V_IH = 2.7V
• Low Level Input Current (I_IL): -1.6mA (max) at V_IL = 0.4V
• Supply Current (I_CC): 12mA (max) per gate

AC Characteristics

• Propagation Delay Time (t_PLH): 15ns (max) from input to output
• Propagation Delay Time (t_PHL): 22ns (max) from input to output
• Output Transition Time (t_TLH, t_THL): 15ns (max)

Package Information

14-Pin Dual In-Line Package (DIP)

The 7427 is available in a standard 14-pin plastic dual in-line package with the following dimensions:

• Package Type: PDIP-14
• Length: 19.3mm (max)
• Width: 6.35mm (max)
• Height: 4.57mm (max)
• Lead Pitch: 2.54mm
• Lead Width: 0.38mm (min)
• Lead Length: 3.3mm (min)

Pin Configuration

The pinout configuration for the 7427 is as follows:

• Pin 1: 1A (Gate 1 Input A)
• Pin 2: 1B (Gate 1 Input B)
• Pin 3: 2A (Gate 2 Input A)
• Pin 4: 2B (Gate 2 Input B)
• Pin 5: 2C (Gate 2 Input C)
• Pin 6: 2Y (Gate 2 Output)
• Pin 7: GND (Ground)
• Pin 8: 3Y (Gate 3 Output)
• Pin 9: 3A (Gate 3 Input A)
• Pin 10: 3B (Gate 3 Input B)
• Pin 11: 3C (Gate 3 Input C)
• Pin 12: 1Y (Gate 1 Output)
• Pin 13: 1C (Gate 1 Input C)
• Pin 14: V_CC (Positive Power Supply)

Functional Description

The 7427 contains three independent 3-input NOR gates. Each gate performs the logical NOR function, which means the output is high only when all inputs are low. The Boolean expression for each gate is Y = (A + B + C)'.

Truth Table

The following truth table describes the operation of each NOR gate:

• Input A = L, Input B = L, Input C = L → Output Y = H
• Input A = H, Input B = X, Input C = X → Output Y = L
• Input A = X, Input B = H, Input C = X → Output Y = L
• Input A = X, Input B = X, Input C = H → Output Y = L

Where: L = Low level (0V), H = High level (3.4V), X =