SN74LS27D NOR Gate IC Equivalent & Substitute Parts

Part Overview

The SN74LS27D is a 3-channel NOR gate logic IC manufactured by Texas Instruments in 14-SOIC surface mount packaging. This component implements three independent 3-input NOR logic functions in a single integrated circuit. The SN74LS27D is currently in Last Time Buy status, indicating end-of-life production. Identifying equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain reliability for applications requiring this logic function.

Substiute Parts

SN74LS27D

Texas InstrumentsIn Stock: 1189SN74LS27D Datasheet

Current PartRFQ

SN74LS27DR

Texas InstrumentsIn Stock: 11629SN74LS27DR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74LS27D is determined by strict equivalence across the following critical parameters:

• Logic function: 3-channel NOR gate with 3 inputs per channel
• Electrical specifications: Supply voltage 4.75V ~ 5.25V, quiescent current 4 mA maximum, output current ratings 400µA (high) and 8mA (low)
• Logic levels: Input low 0.8V, input high 2V
• Timing: Maximum propagation delay 15ns at 5V with 15pF load
• Package: 14-SOIC surface mount form factor
• Compliance: ROHS3 compliant, MSL Level 1

The SN74LS27DR qualifies as a direct substitute based on identical electrical and functional parameters. The primary difference is packaging format: the SN74LS27D is supplied in Tube packaging, while the SN74LS27DR is supplied in Tape & Reel (TR) format. Both parts share the same base product number (74LS27) and maintain full functional and electrical compatibility.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS27DR is the recommended substitute for the SN74LS27D. Both parts are manufactured by Texas Instruments and maintain identical electrical and functional specifications across all critical parameters. The SN74LS27DR carries Active product status, ensuring continued availability and supply chain support, whereas the SN74LS27D is in Last Time Buy status.

Both parts meet ROHS3 compliance requirements and carry MSL Level 1 rating, indicating no moisture sensitivity constraints during storage and handling. The substitution is electrically transparent with no design modifications required. The only consideration is packaging format: the SN74LS27DR is supplied in Tape & Reel format, which is standard for automated assembly processes, while the SN74LS27D is supplied in Tube format.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS27DR directly replace the SN74LS27D in existing designs?

A: Yes. The SN74LS27DR is a direct electrical and functional equivalent. All logic levels, timing characteristics, supply voltage requirements, and output drive capabilities are identical. No circuit modifications are required.

Q: What is the difference between Tube and Tape & Reel packaging?

A: Tube packaging supplies individual components in a plastic tube, suitable for manual assembly or small-quantity handling. Tape & Reel packaging supplies components on a continuous reel in embossed tape, optimized for automated pick-and-place assembly equipment. Both formats contain the same die and provide identical electrical performance.

Q: Why is the SN74LS27D marked as Last Time Buy?

A: Last Time Buy status indicates that Texas Instruments has discontinued production of this part number. Existing inventory may be available from distributors, but no new production runs are scheduled. The SN74LS27DR remains in Active status and is the recommended long-term alternative.

Q: Are there any compliance or certification differences between these parts?

A: No. Both parts carry identical ROHS3 compliance and MSL Level 1 ratings. They meet the same environmental and regulatory standards.

Q: Can I mix SN74LS27D and SN74LS27DR parts in the same production batch?

A: Yes. Since both parts are electrically and functionally identical, they can be used interchangeably within the same design. The only practical consideration is assembly equipment compatibility with the respective packaging formats.