74251

M54/74HC251: 8-Channel Multiplexer (3-State)

Overview

The M54/74HC251 is a high-speed CMOS 8-channel multiplexer featuring 3-state outputs. This integrated circuit is designed for applications requiring high-speed data selection and routing. The device provides both true (Y) and complement (W) outputs, making it versatile for logic-level signal processing. Fabricated using advanced silicon technology, the M54/74HC251 ensures low power consumption while maintaining high-speed operation, making it suitable for a wide range of digital systems.

The multiplexer selects one of eight binary inputs (D0-D7) based on the three select lines (S0, S1, S2) and routes it to the output. The 3-state output capability allows multiple devices to be connected to a common bus without interference, enabling efficient data communication in complex systems.

Features

• High-Speed Operation: Optimized for high-performance digital systems with fast propagation delays.
• 3-State Outputs: Allows bus-oriented applications with output enable control (OE).
• Complementary Outputs: Provides both true (Y) and inverted (W) outputs for flexible signal routing.
• Low Power Consumption: CMOS technology ensures minimal power dissipation.
• Wide Operating Voltage Range: Compatible with 2V to 6V supply voltages.
• High Noise Immunity: Robust design ensures reliable operation in noisy environments.
• Standard Pin Configuration: Follows industry-standard pinouts for easy integration.
• Latch-Up Protection: Exceeds 250mA per JESD78B Class II standards.

Applications

The M54/74HC251 is widely used in digital systems where data selection and routing are required. Key applications include:

• Data Multiplexing: Selection of one data line from multiple sources in communication systems.
• Bus Switching: Enables shared bus architectures in microprocessor and microcontroller systems.
• Signal Routing: Used in audio/video switching and digital signal processing.
• Memory Addressing: Facilitates address decoding in memory systems.
• Industrial Control Systems: Provides reliable data selection in automation and control applications.
• Test Equipment: Used in signal routing for test and measurement devices.

Electrical Characteristics

The following table summarizes the key electrical specifications of the M54/74HC251 under typical operating conditions (V_CC = 4.5V, T_A = 25°C):

• Supply Voltage Range (V_CC): 2V to 6V
• Input Voltage Range (V_IN): 0V to V_CC
• Output Voltage Range (V_OUT): 0V to V_CC
• Propagation Delay (t_PD): 13ns max (V_CC = 4.5V)
• Input Capacitance (C_IN): 3.5pF typical
• Output Drive Capability: 10 LSTTL loads
• Power Dissipation (P_D): 500mW max
• Operating Temperature Range (T_A): -40°C to +125°C

Package Information

The M54/74HC251 is available in multiple package options to suit different application requirements:

• 16-pin DIP (Dual In-line Package):
  • Package Code: 648-08
  • Dimensions: 19.3mm x 6.35mm
  • Pin Pitch: 2.54mm
• 16-pin SOIC (Small Outline Integrated Circuit):
  • Package Code: 751B-05
  • Dimensions: 9.9mm x 3.9mm
  • Pin Pitch: 1.27mm
• 16-pin TSSOP (Thin Shrink Small Outline Package):
  • Package Code: 948F-03
  • Dimensions: 5mm x 4.4mm
  • Pin Pitch: 0.65mm

The device is also available in tape-and-reel packaging for automated assembly processes. All packages are RoHS compliant and lead-free.

Functional Description

The M54/74HC251 operates as an 8-channel digital multiplexer with 3-state outputs. The device features:

• Eight Data Inputs (D0-D7): These pins accept the digital signals to be multiplexed.
• Three Select Inputs (S0-S2): These binary inputs determine which of the eight data inputs is routed to the output.
• Output Enable (OE): Active-low control that places the outputs in high-impedance state when high.
• True Output (Y): Provides the selected input data in non-inverted form.
• Complement Output (W): Provides the inverted version of the selected input data.

The truth table below illustrates the device operation:

Where: L = Low, H = High, X = Don't Care, Z = High Impedance, Dx' = Complement of Dx

Recommended Operating Conditions

For optimal performance and reliability, the following operating conditions should be maintained:

• Supply Voltage: 4.5V to 5.5V for full specified performance
• Input Rise/Fall Time: < 500ns (V_CC = 5V)
• Output Load Capacitance: < 50pF for maximum speed
• Storage Temperature Range: -65°C to +150°C

Quality and Reliability

The M54/74HC251 is manufactured under strict quality control procedures and meets