74F191SC Binary Counter IC Equivalent & Substitute Parts

Part Overview

The 74F191SC is a 4-bit binary counter IC manufactured by onsemi, designed for synchronous up/down counting applications with positive edge triggering. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing production and maintenance applications. The 74F191SC operates at a count rate of 100 MHz with a supply voltage range of 4.5 V to 5.5 V, housed in a 16-SOIC surface mount package.

Substiute Parts

74F191SC

onsemiIn Stock: 103674F191SC Datasheet

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SN74LS191D

Texas InstrumentsIn Stock: 1533SN74LS191D Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74F191SC is determined by the following critical parameters:

• Package Compatibility: Both main and substitute parts must use 16-SOIC surface mount packaging with identical physical dimensions (0.154", 3.90mm Width)
• Functional Equivalence: Counter IC must be 4-bit binary counter with up/down direction capability and positive edge triggering
• Timing Architecture: Synchronous timing is required for functional compatibility
• Electrical Specifications: Supply voltage range and operating temperature must support the application requirements
• Logic Family Compatibility: The 74F and 74LS logic families share compatible pin configurations and functional behavior within their respective performance specifications

The SN74LS191D from Texas Instruments qualifies as a substitute based on matching package type, counter configuration, direction capability, and synchronous timing. Differences in count rate (25 MHz vs. 100 MHz) and supply voltage tolerance reflect the inherent characteristics of the 74LS logic family versus the 74F family.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS191D is suitable as a substitute for the 74F191SC in applications where the count rate requirement does not exceed 25 MHz. Both components share identical package specifications, functional counter architecture, and operating temperature ranges, enabling direct pin-compatible replacement.

The 74F191SC is classified as obsolete, while the SN74LS191D carries a Last Time Buy status. For new designs or long-term production requirements, component availability and product lifecycle status should be evaluated against application timing specifications.

The SN74LS191D is ROHS3 compliant, whereas the 74F191SC status is not specified in the provided data. Both components are REACH unaffected and carry EAR99 ECCN classification.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS191D directly replace the 74F191SC in existing designs?

A: Direct pin-compatible replacement is possible due to identical 16-SOIC packaging and matching counter functionality. However, the reduced count rate of 25 MHz versus 100 MHz must be verified against circuit timing requirements before implementation.

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

A: The 74F family operates at higher count rates (100 MHz) with a broader supply voltage tolerance (4.5 V ~ 5.5 V), while the 74LS family operates at lower count rates (25 MHz) with a narrower supply voltage range (4.75 V ~ 5.25 V). Both families use identical pin configurations for equivalent counter functions.

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

A: The SN74LS191D is ROHS3 compliant. Both components are REACH unaffected and classified under EAR99. Compliance requirements for your specific application should be verified against these certifications.

Q: What is the significance of the 16-SOIC package specification?

A: The 16-SOIC (0.154", 3.90mm Width) package ensures mechanical and electrical compatibility between the main part and substitute. This standardized surface mount package allows direct PCB footprint compatibility without redesign.

Q: How does the supply voltage range difference affect substitution?

A: The SN74LS191D requires a narrower supply voltage window (4.75 V ~ 5.25 V) compared to the 74F191SC (4.5 V ~ 5.5 V). Applications operating at the extremes of the 74F range may require voltage regulation adjustments when using the 74LS substitute.