SN74LS38D NAND Gate IC Equivalent & Substitute Parts

Part Overview

The SN74LS38D is a 4-channel 2-input NAND gate IC with open collector output, manufactured by Texas Instruments in 14-SOIC surface mount packaging. This logic component operates within the 74LS TTL family and is classified as Last Time Buy status, indicating limited availability for future procurement. Identifying equivalent and substitute parts is essential for design continuity, inventory management, and long-term production planning when the primary part reaches end-of-life.

Substiute Parts

SN74LS38D

Texas InstrumentsIn Stock: 1846SN74LS38D Datasheet

Current PartRFQ

SN74LS26D

MotorolaIn Stock: 8528SN74LS26D Datasheet

DirectRFQ

SN74LS38DR

Texas InstrumentsIn Stock: 2450SN74LS38DR Datasheet

MFR RecommendedRFQ

SN74LS03D

Texas InstrumentsIn Stock: 1575SN74LS03D Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SN74LS38D is determined by the following critical parameters:

• Logic function: NAND gate with 4 channels and 2 inputs per channel
• Output configuration: Open collector topology
• Package format: 14-SOIC surface mount
• Supply voltage compatibility: 4.75V ~ 5.25V operating range
• Input logic thresholds: Low ≤ 0.8V, High ≥ 2V
• Operating temperature range: 0°C ~ 70°C

Substitute parts must maintain identical logic function, channel count, input configuration, and package type. Variations in output current ratings, propagation delay specifications, and quiescent current are permissible within the 74LS family design envelope, provided the substitute part meets or exceeds the electrical performance requirements of the application circuit.

Parameter Comparison

Engineering Selection Recommendations

SN74LS38DR (Manufacturer Recommended Substitute)

The SN74LS38DR is the primary recommended substitute for the SN74LS38D. Both parts are manufactured by Texas Instruments, share identical electrical specifications including 24mA output current and 32ns propagation delay at 45pF load, and maintain full ROHS3 compliance. The SN74LS38DR carries Active product status, ensuring continued availability and supply chain stability. The primary distinction is packaging format: SN74LS38DR is supplied in Cut Tape and Digi-Reel format, whereas SN74LS38D is supplied in Tube packaging. This substitute provides direct functional and electrical equivalence with superior long-term availability.

SN74LS03D (Functional Equivalent with Output Current Variation)

The SN74LS03D is a functional substitute with identical logic configuration and ROHS3 compliance. This part exhibits different output current specifications (250µA high, 16mA low) and reduced propagation delay load capacity (15pF versus 45pF). The SN74LS03D is classified as Last Time Buy, similar to the main part. Selection of this substitute requires circuit-level analysis to confirm that the reduced output current and load capacity specifications are compatible with the application requirements.

SN74LS26D (Not Recommended)

The SN74LS26D, manufactured by Motorola, maintains functional equivalence in logic configuration and package type. However, this part is classified as Obsolete and carries RoHS non-compliance status. The output current specification is limited to 8mA (versus 24mA for the main part), and propagation delay load capacity is reduced to 15pF. This substitute is not recommended for new designs or long-term production applications due to obsolescence and regulatory non-compliance.

Frequently Asked Questions (FAQ)

Q: Can SN74LS38DR be used as a direct replacement for SN74LS38D in existing designs?

A: Yes. The SN74LS38DR is electrically and functionally identical to the SN74LS38D. Both parts share the same logic specifications, output current ratings (24mA), propagation delay (32ns @ 45pF), and ROHS3 compliance. The only difference is packaging format (Tape & Reel versus Tube). No circuit modifications are required.

Q: What are the key differences between SN74LS38D and SN74LS03D?

A: Both parts are 4-channel 2-input NAND gates with open collector output in 14-SOIC packaging. The SN74LS03D has reduced output current (16mA low versus 24mA) and lower propagation delay load capacity (15pF versus 45pF). Circuit compatibility depends on whether the application can operate within these reduced specifications.

Q: Why is SN74LS26D not recommended as a substitute?

A: The SN74LS26D is classified as Obsolete and is RoHS non-compliant. Additionally, it provides only 8mA output current compared to the 24mA specification of the main part, which may be insufficient for certain load conditions. For new designs and regulated applications, this part should not be selected.

Q: Are all substitute parts available in the same 14-SOIC package?

A: Yes. All substitute parts listed are available in 14-SOIC (0.154", 3.90mm Width) surface mount packaging, ensuring mechanical and electrical compatibility with existing PCB designs. Packaging format (Tube, Cut Tape, or Tape & Reel) may vary but does not affect component functionality.

Q: What is the significance of "Last Time Buy" status for the SN74LS38D?

A: Last Time Buy status indicates that the manufacturer has announced end-of-life for this part. Existing inventory will be sold until depletion, after which the part will no longer be available. Designers should transition to the SN74LS38DR (Active status) for new projects and long-term production continuity.