SN74ALS156N

Overview

The SN74ALS156N is a dual 2-line to 4-line decoder and demultiplexer manufactured by Texas Instruments. It operates within a supply voltage range of 4.5 V to 5.5 V and features open-collector outputs. The device supports a propagation delay of 14 ns and functions across an operating temperature range from 0°C to +70°C. Packaged in a 16-pin DIP, it includes Schottky diodes for input clamping to suppress line ringing.

Feature Summary

• Dual configuration providing two independent 2-to-4 decoding or demultiplexing channels
• Open-collector output structure suitable for wired-OR logic applications
• Integrated high-performance Schottky diodes on all inputs to suppress line ringing

Applications

• Dual 2-Line to 4-Line Decoder
• Dual 1-Line to 4-Line Demultiplexer
• 3-Line to 8-Line Decoder (via cascading)
• 1-Line to 8-Line Demultiplexer (via cascading)

Procurement Notes

Verify the package type matches the required footprint, as the 'N' suffix typically denotes a plastic DIP package. Confirm that the open-collector output requirement aligns with the system design, as pull-up resistors are necessary for proper high-state operation. Ensure the 4.5V to 5.5V supply voltage range is compatible with the target circuit's power rails before procurement.

Selection Notes

Select this component when a dual-channel decoding solution with open-collector outputs is required. It is suitable for systems needing signal routing or address decoding where the load can be driven by external pull-ups. Consider the 14 ns propagation delay for timing constraints. This part is appropriate for general-purpose digital logic applications requiring robust input protection against ringing.

Part Context

The SN74ALS156N belongs to the Texas Instruments SN74ALS series, which utilizes Advanced Low-power Schottky technology. This family offers faster switching speeds than standard LS logic while maintaining low power consumption. The device is designed for use in various digital systems requiring reliable decoding and multiplexing functions with enhanced noise immunity due to internal input clamping.

Replacement Considerations

Check for direct pin-compatible alternatives within the same ALS family, such as other variants of the SN74ALS156 series. Verify that any substitute maintains the open-collector output characteristic and the 2-to-4 channel configuration. Ensure the replacement part supports the same voltage and temperature specifications.