SN74ALS257ANS Equivalent & Substitute Parts

Part Overview

The SN74ALS257ANS is a Data Selector/Multiplexer integrated circuit manufactured by Texas Instruments, featuring a 4 x 2:1 circuit configuration in a 16-SOIC surface mount package. This component is classified as Last Time Buy, indicating discontinued production with limited inventory availability. The identification of equivalent and substitute parts is necessary to ensure design continuity and procurement flexibility for applications requiring 4 x 2:1 multiplexer functionality with identical electrical and mechanical specifications.

Substiute Parts

SN74ALS257ANS

Texas InstrumentsIn Stock: 3636SN74ALS257ANS Datasheet

Current PartRFQ

SN74ALS257ANSR

Texas InstrumentsIn Stock: 3268SN74ALS257ANSR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SN74ALS257ANS is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Requirements:

• Circuit configuration: 4 x 2:1 multiplexer topology
• Independent circuits: 1
• Output current specifications: 2.6mA (high), 24mA (low)
• Supply voltage range: 4.5V ~ 5.5V
• Operating temperature range: 0°C ~ 70°C
• Logic series: 74ALS

Mechanical Equivalence Requirements:

• Package type: 16-SOIC surface mount
• Package dimensions: 0.209" width, 5.30mm width
• Mounting configuration: Surface mount

Compliance Requirements:

• RoHS3 compliance
• Moisture sensitivity level: 1 (Unlimited)

The SN74ALS257ANSR qualifies as a direct substitute based on identical electrical specifications, mechanical packaging, and compliance certifications. The primary distinction is packaging format: the substitute is supplied in Tape & Reel (TR) configuration versus the prototype packaging of the main part, and carries Active product status rather than Last Time Buy.

Parameter Comparison

Engineering Selection Recommendations

For New Designs and Procurement:

The SN74ALS257ANSR is the appropriate selection for new applications and ongoing procurement. This part maintains identical electrical and mechanical specifications to the SN74ALS257ANS while offering Active product status, ensuring long-term availability and supply chain stability. The Tape & Reel packaging format is standard for production-volume applications and provides cost efficiency in manufacturing environments.

For Existing Inventory and Legacy Support:

The SN74ALS257ANS remains functionally equivalent for applications currently utilizing this part number. However, given Last Time Buy status, transition planning to the SN74ALS257ANSR is recommended for designs requiring component replenishment beyond current inventory levels (3588 Pcs available).

Compliance Considerations:

Both parts satisfy ROHS3 compliance requirements and carry MSL Level 1 (Unlimited) moisture sensitivity classification, permitting unrestricted storage and handling without specialized environmental controls. No compliance barriers exist to substitution.

Frequently Asked Questions (FAQ)

Q: Can the SN74ALS257ANSR directly replace the SN74ALS257ANS in existing circuit designs?

A: Yes. Both parts are electrically and mechanically identical across all specified parameters: 4 x 2:1 multiplexer configuration, 2.6mA/24mA output current ratings, 4.5V–5.5V supply voltage, 0°C–70°C operating temperature, and 16-SOIC surface mount packaging. Pin-for-pin compatibility is maintained.

Q: What is the significance of the packaging format difference (Prototype vs. Tape & Reel)?

A: Packaging format affects supply chain logistics and handling procedures, not electrical or mechanical function. Prototype packaging is typically used for engineering samples and limited-quantity orders. Tape & Reel (TR) packaging is standard for production manufacturing, offering automated assembly compatibility and cost efficiency at volume. Both formats contain identical die and lead frame specifications.

Q: Why is the SN74ALS257ANS classified as Last Time Buy?

A: Last Time Buy status indicates Texas Instruments has discontinued production of this specific part number variant. Existing inventory (3588 Pcs) represents the final available stock. The SN74ALS257ANSR, with identical specifications and Active status, is the designated successor for ongoing applications.

Q: Are there any thermal or environmental performance differences between these parts?

A: No. Both parts operate across the identical temperature range (0°C–70°C) and carry the same MSL Level 1 classification, indicating no moisture sensitivity restrictions. Environmental performance characteristics are equivalent.

Q: What is the base product number for these parts?

A: The base product number is 74ALS257, representing the core multiplexer design. The SN74ALS257ANS and SN74ALS257ANSR are packaging and distribution variants of this base product.