SN74LS161AD Equivalent & Substitute Parts

Part Overview

The SN74LS161AD is a 4-bit binary counter IC manufactured by Texas Instruments, designed for synchronous counting applications with positive edge triggering. This component operates within the 74LS logic family and is commonly used in digital logic circuits requiring precise counting functionality at up to 25 MHz. The main part is currently in Last Time Buy status, making identification of suitable substitutes essential for ongoing design support and procurement planning. The SN74LS161ADR serves as the direct manufacturer-recommended substitute, offering identical electrical and mechanical specifications with improved availability.

Substiute Parts

SN74LS161AD

Texas InstrumentsIn Stock: 4021SN74LS161AD Datasheet

Current PartRFQ

SN74LS161ADR

Texas InstrumentsIn Stock: 10258SN74LS161ADR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The SN74LS161ADR qualifies as a direct substitute for the SN74LS161AD based on matching all critical electrical and mechanical parameters. Substitution eligibility is determined by the following criteria:

• Identical logic type, bit configuration, and counting direction
• Matching count rate specification of 25 MHz
• Identical trigger type (positive edge) and reset mechanism (asynchronous)
• Matching supply voltage range (4.75 V ~ 5.25 V)
• Identical operating temperature range (0°C ~ 70°C)
• Identical package specification (16-SOIC with 0.154" width, 3.90mm)
• Matching surface mount mounting type
• Identical RoHS3 compliance and MSL rating

The only difference between these parts is the packaging format: the main part uses Tube packaging, while the substitute uses Tape & Reel (TR) packaging. This distinction affects procurement and handling but does not impact electrical or mechanical compatibility.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS161ADR is the manufacturer-recommended substitute for the SN74LS161AD. Both parts maintain identical electrical specifications and physical package dimensions, ensuring direct compatibility in circuit applications. The primary distinction is product status: the SN74LS161AD is designated Last Time Buy, indicating limited future availability, while the SN74LS161ADR maintains Active status with higher inventory levels (10,200 pcs vs. 3,944 pcs).

Both parts carry ROHS3 compliance and identical MSL ratings, meeting current regulatory requirements. The packaging difference (Tube vs. Tape & Reel) reflects standard distribution formats and does not affect component performance or board-level integration. For new designs or long-term production requirements, the SN74LS161ADR is the appropriate selection due to its active product status and superior availability.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS161ADR directly replace the SN74LS161AD in existing designs?

A: Yes. Both parts are electrically and mechanically identical. They share the same 16-SOIC package dimensions, supply voltage range, operating temperature specifications, and functional characteristics. The only difference is packaging format (Tube vs. Tape & Reel) and product status.

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

A: Tube packaging is typically used for manual handling and smaller quantity orders, while Tape & Reel packaging is standard for automated assembly processes and higher-volume production. The actual component specifications and performance are identical. Selection depends on procurement method and assembly process requirements.

Q: Why is the SN74LS161AD listed as Last Time Buy?

A: Last Time Buy status indicates that the manufacturer is discontinuing this specific packaging variant. The SN74LS161ADR (Tape & Reel format) remains in active production, making it the recommended long-term alternative for continued supply.

Q: Are there any electrical performance differences between these parts?

A: No. Both parts operate at 25 MHz count rate, support 4-bit binary counting with positive edge triggering, and maintain identical supply voltage (4.75 V ~ 5.25 V) and temperature specifications (0°C ~ 70°C).

Q: What compliance certifications apply to both parts?

A: Both the SN74LS161AD and SN74LS161ADR are ROHS3 compliant and carry MSL rating of 1 (Unlimited), indicating no moisture sensitivity restrictions during storage or handling.