SN74ALS33AN NOR Gate IC Equivalent & Substitute Parts

Part Overview

The SN74ALS33AN is a 4-channel NOR gate integrated circuit manufactured by Texas Instruments in the 74ALS logic family. This component features open collector outputs and operates within a 4.5V to 5.5V supply voltage range. The device is classified as obsolete, making identification of compatible substitute parts essential for ongoing system maintenance and new design implementations where legacy compatibility is required.

Substiute Parts

SN74ALS33AN

Texas InstrumentsIn Stock: 810SN74ALS33AN Datasheet

Current PartRFQ

SN74LS33N

Texas InstrumentsIn Stock: 2372SN74LS33N Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74ALS33AN is determined by the following critical parameters:

• Logic Function: NOR gate with 4 channels and 2 inputs per channel
• Output Configuration: Open collector topology
• Package Type: 14-DIP through-hole mounting
• Supply Voltage Range: Compatible operation within specified voltage window
• Logic Levels: Input and output voltage thresholds must align with system requirements
• Propagation Delay: Maximum delay specifications for timing-critical applications
• Operating Temperature Range: 0°C to 70°C commercial grade

The SN74LS33N qualifies as a direct substitute based on matching logic function, output configuration, package type, and operating temperature range. Both devices implement identical NOR gate logic with open collector outputs in 14-DIP packaging.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS33N serves as the primary substitute for the obsolete SN74ALS33AN. Selection is justified by:

• Functional Equivalence: Identical NOR gate logic configuration with matching input/output specifications
• Package Compatibility: Both devices use 14-DIP through-hole packaging, enabling direct board-level replacement
• Electrical Compatibility: Supply voltage ranges overlap at 5V nominal operation; logic levels and output current ratings are identical
• Compliance Status: The SN74LS33N maintains ROHS3 compliance and REACH unaffected status, meeting modern regulatory requirements
• Product Availability: The SN74LS33N is classified as active product status with established supply channels, ensuring long-term availability compared to the obsolete SN74ALS33AN

The SN74LS33N exhibits slightly faster propagation delay (32ns versus 33ns) and operates with a narrower supply voltage tolerance (4.75V–5.25V versus 4.5V–5.5V). These differences are negligible for standard logic applications operating at nominal 5V supply voltage.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS33N directly replace the SN74ALS33AN without PCB modifications?

A: Yes. Both devices use identical 14-DIP packaging with matching pin assignments. Direct socket substitution is possible without circuit board redesign.

Q: What are the key differences between the 74ALS and 74LS logic families?

A: The 74ALS (Advanced Low-power Schottky) and 74LS (Low-power Schottky) families differ in power consumption and propagation delay characteristics. For the NOR gate function, both families provide equivalent logic operation with compatible electrical specifications at 5V nominal supply.

Q: Are there supply voltage considerations when substituting these parts?

A: The SN74ALS33AN accepts 4.5V–5.5V supply, while the SN74LS33N accepts 4.75V–5.25V. Systems operating at nominal 5V fall within both ranges. Systems requiring operation below 4.75V or above 5.25V must retain the SN74ALS33AN or verify alternative substitutes.

Q: Does the SN74LS33N meet current RoHS and REACH compliance requirements?

A: Yes. The SN74LS33N is ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory standards for electronic component procurement.

Q: How do propagation delay specifications affect circuit performance?

A: The SN74LS33N exhibits 32ns maximum propagation delay compared to 33ns for the SN74ALS33AN. This 1ns difference is negligible for most logic applications and does not affect timing-critical circuit behavior in standard digital systems.