SN74ALS33AD

Overview

The SN74ALS33AD is a quad 2-input positive-NOR buffer manufactured by Texas Instruments in the ALS logic series. It features four independent gates with open-collector outputs housed in a 14-pin Small-Outline (D) package. The device operates within a supply voltage range of 4.5 V to 5.5 V and supports an operating temperature range from 0°C to 70°C. Electrical characteristics include a maximum low-level output current of 24 mA and propagation delays ranging from 2 ns to 33 ns depending on transition direction.

Feature Summary

• Contains four independent 2-input positive-NOR buffers
• Features open-collector outputs requiring external resistive pullup
• Supports wired-AND applications for higher voltage levels

Applications

• Wired-AND logic configurations
• Positive-NOR buffering circuits
• Open-collector interface driving

Procurement Notes

Verify that the specific ordering suffix matches the required package type, as the SN74ALS33A family includes various physical packages such as plastic DIP and ceramic carriers. Confirm the manufacturer's active status and lifecycle stage before procurement, as discontinuation notices may apply to older logic families. Ensure the selected variant meets the necessary environmental specifications for the intended deployment environment.

Selection Notes

Select this component when designing circuits requiring multiple NOR functions with open-collector capabilities. The ALS series offers improved speed and power consumption compared to standard TTL. Verify that the application circuit includes appropriate pullup resistors to ensure correct high-level output performance. Consider the 14-pin SOIC footprint constraints during PCB layout planning.

Part Context

This part belongs to the Texas Instruments SN74ALS33A family of logic ICs. The 'D' suffix specifically denotes the plastic Small-Outline package variant. The family provides quad 2-input NOR functionality with open-collector outputs, designed for general-purpose digital logic applications requiring wired-AND capabilities or higher voltage level shifting.

Replacement Considerations

SN74LS33DR

FAQ

Why are external resistors required for this component?

The SN74ALS33AD utilizes open-collector outputs which cannot actively drive the output high. External resistive pullups are mandatory to establish the high logic state and define the output voltage level.

What Boolean function does this device perform?

The device performs the Boolean function Y = A + B (positive logic OR) or equivalently Y = A · B (negative logic AND), functioning as a positive-NOR gate.