74ACT520SJX Equivalent & Substitute Parts

Part Overview

The 74ACT520SJX is an 8-bit magnitude comparator with active low output (A=B function) manufactured by onsemi in a 20-SOIC surface mount package. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations. The 74ACT series logic family provides standard digital comparison functionality with specified electrical performance across industrial temperature ranges.

Substiute Parts

74ACT520SJX

onsemiIn Stock: 99874ACT520SJX Datasheet

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SN74ALS521NSR

Texas InstrumentsIn Stock: 3131SN74ALS521NSR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74ACT520SJX is determined by the following critical parameters:

• Functional equivalence: 8-bit identity comparator with A=B output function
• Logic family compatibility: Active low output configuration
• Electrical specifications: 4.5V to 5.5V supply voltage range
• Package compatibility: 20-SOIC surface mount package
• Pin configuration: Identical pinout required for direct replacement

The SN74ALS521NSR from Texas Instruments meets these substitution criteria as a 74ALS series 8-bit magnitude comparator with identical output function, supply voltage range, and package footprint. Both components operate within the same logic family standards and share compatible electrical interfaces.

Parameter Comparison

Engineering Selection Recommendations

The SN74ALS521NSR is a direct functional substitute for the 74ACT520SJX based on matching logic family standards, identical bit width, output configuration, and package footprint. Key considerations for selection:

Electrical Performance: The SN74ALS521NSR exhibits longer propagation delay (20ns versus 10ns) and reduced output high current (2.6mA versus 24mA). These differences are acceptable in applications where timing margins and output drive requirements do not demand the faster ACT series performance characteristics.

Temperature Range: The SN74ALS521NSR operates across 0°C to 70°C, which is narrower than the 74ACT520SJX range of -40°C to 85°C. Applications requiring extended temperature operation below 0°C or above 70°C must verify compatibility with system thermal specifications.

Product Status and Availability: The SN74ALS521NSR maintains active product status with confirmed inventory availability (3100 units), whereas the 74ACT520SJX is obsolete. For new designs and ongoing production, the SN74ALS521NSR provides supply chain continuity.

Compliance: Both components carry identical REACH and ECCN classifications (REACH Unaffected, EAR99), ensuring regulatory equivalence for export and environmental compliance purposes.

Frequently Asked Questions (FAQ)

Q: Can the SN74ALS521NSR directly replace the 74ACT520SJX in existing designs?

A: Yes, the SN74ALS521NSR provides direct functional replacement with identical pinout and package footprint. However, verify that system timing requirements accommodate the 20ns propagation delay and that output drive specifications do not depend on the higher current capability of the ACT series.

Q: What are the key differences between these two comparators?

A: Both are 8-bit identity comparators with active low A=B output and identical supply voltage range. The primary differences are propagation delay (10ns versus 20ns), output high current (24mA versus 2.6mA), and operating temperature range (-40°C to 85°C versus 0°C to 70°C).

Q: Are there package compatibility concerns?

A: Both components use the 20-SOIC package with identical 0.209" (5.30mm) width. No package-level modifications are required for substitution.

Q: Which comparator should be selected for new designs?

A: The SN74ALS521NSR is recommended for new designs due to active product status, confirmed availability, and equivalent functional performance for standard logic applications. The 74ACT520SJX should not be selected for new designs as it is obsolete.

Q: Does operating temperature range affect substitution suitability?

A: The narrower temperature range of the SN74ALS521NSR (0°C to 70°C) may limit suitability for applications requiring extended temperature operation. Verify system thermal specifications before substitution in temperature-critical applications.