74F191PC Binary Counter IC Equivalent & Substitute Parts

Part Overview

The 74F191PC is a 4-bit binary counter IC manufactured by onsemi, designed for synchronous up/down counting applications with positive edge triggering. This component features a count rate of 100 MHz and operates across a supply voltage range of 4.5 V to 5.5 V. The device is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production support where original stock becomes unavailable.

Substiute Parts

74F191PC

onsemiIn Stock: 344874F191PC Datasheet

Current PartRFQ

SN74LS191N

Texas InstrumentsIn Stock: 13547SN74LS191N Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74F191PC is determined by the following critical parameters:

• Logic Function: Binary counter with 4-bit capacity, up/down counting capability, and synchronous timing
• Electrical Interface: Positive edge triggering, supply voltage compatibility within specified ranges
• Physical Form Factor: 16-DIP package with 0.300" (7.62mm) pitch for through-hole mounting
• Performance Threshold: Count rate capability must support the application frequency requirements

The SN74LS191N qualifies as a substitute based on matching logic function, package form factor, and core electrical characteristics. However, the count rate differs between the main part and substitute, requiring evaluation against specific application timing requirements.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS191N from Texas Instruments is an active product with ROHS3 compliance, providing long-term availability and regulatory alignment for new designs. The primary consideration for substitution is the count rate differential: the 74F191PC operates at 100 MHz while the SN74LS191N operates at 25 MHz. Selection between these parts depends on whether the application timing requirements can be satisfied by the 25 MHz maximum count rate of the substitute.

Both parts share identical package geometry, pin configuration, and core counter functionality (4-bit, up/down, synchronous, positive edge triggered). Supply voltage ranges overlap sufficiently for most standard 5 V logic applications, though the 74F191PC permits operation down to 4.5 V while the SN74LS191N minimum is 4.75 V.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS191N directly replace the 74F191PC in existing designs?

A: Direct replacement is possible from a functional and physical standpoint. Both devices are 4-bit binary counters in 16-DIP packages with identical pin assignments. However, the count rate specification differs: verify that your application does not require counting speeds exceeding 25 MHz, which is the maximum for the SN74LS191N.

Q: What is the primary difference between these two counter ICs?

A: The 74F191PC (74F series) operates at 100 MHz count rate, while the SN74LS191N (74LS series) operates at 25 MHz. The 74F series uses faster logic technology. Both maintain the same 4-bit counter architecture and 16-DIP package form factor.

Q: Are there supply voltage compatibility concerns?

A: Both parts operate within standard 5 V logic supply ranges. The 74F191PC accepts 4.5 V to 5.5 V, while the SN74LS191N accepts 4.75 V to 5.25 V. For applications using standard 5 V supplies, both are compatible. Applications requiring operation below 4.75 V must use the 74F191PC.

Q: Is the SN74LS191N suitable for new production designs?

A: Yes. The SN74LS191N is an active product with ROHS3 compliance, making it appropriate for new designs requiring long-term component availability and regulatory compliance. The 74F191PC is obsolete and should not be specified for new designs.

Q: Do these parts require different PCB layouts or mounting procedures?

A: No. Both devices use identical 16-DIP through-hole packaging with 0.300" (7.62mm) pitch. PCB layouts, footprints, and mounting procedures are interchangeable.