SN74LS191D Equivalent & Substitute Parts

Part Overview

The SN74LS191D is a 4-bit binary counter IC manufactured by Texas Instruments, housed in a 16-SOIC surface mount package. This synchronous counter operates at a maximum count rate of 25 MHz with up/down counting capability and positive edge triggering. The device is currently in Last Time Buy status, indicating discontinued production. Identifying equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain reliability for applications requiring this counter functionality.

Substiute Parts

SN74LS191D

Texas InstrumentsIn Stock: 1533SN74LS191D Datasheet

Current PartRFQ

SN74LS191DR

Texas InstrumentsIn Stock: 4495SN74LS191DR Datasheet

MFR RecommendedRFQ

SN74LS169BD

Texas InstrumentsIn Stock: 1177SN74LS169BD Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the SN74LS191D is determined by strict equivalence across the following critical parameters:

• Logic Type: Binary Counter
• Number of Bits per Element: 4 Bit
• Direction: Up, Down capability
• Timing: Synchronous operation
• Count Rate: 25 MHz minimum
• Trigger Type: Positive Edge
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 16-SOIC (0.154", 3.90mm Width)

The identified substitutes maintain full parametric equivalence across all electrical and mechanical specifications. Differences in product status and packaging format (Cut Tape vs. Tube) do not affect functional compatibility.

Parameter Comparison

Engineering Selection Recommendations

Both SN74LS191DR and SN74LS169BD are valid substitutes for the SN74LS191D based on parametric equivalence. Selection between these options should be based on the following factors:

SN74LS191DR is the manufacturer-recommended substitute, currently in Active product status with higher inventory availability (4466 pcs). This part is supplied in Cut Tape and Digi-Reel® packaging formats, suitable for automated assembly processes.

SN74LS169BD is a parametric equivalent also in Active product status with available inventory (1115 pcs). This part is supplied in Tube packaging, matching the original SN74LS191D format.

Both substitutes maintain full compliance with ROHS3, REACH, and MSL requirements. Selection should prioritize Active status parts to ensure long-term supply chain stability, as the original SN74LS191D is in Last Time Buy status.

Frequently Asked Questions (FAQ)

Q: Can SN74LS191DR be used as a direct replacement for SN74LS191D?

A: Yes. Both parts are electrically and mechanically equivalent across all specified parameters. The primary difference is packaging format (Cut Tape vs. Tube) and product status (Active vs. Last Time Buy). Functional compatibility is complete.

Q: What is the difference between SN74LS191DR and SN74LS169BD?

A: Both parts are parametric equivalents with identical electrical specifications and package dimensions. The difference is packaging format: SN74LS191DR uses Cut Tape and Digi-Reel® formats, while SN74LS169BD uses Tube format. Selection depends on assembly process requirements.

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

A: No. All three parts (SN74LS191D, SN74LS191DR, and SN74LS169BD) maintain identical compliance status: ROHS3 Compliant, REACH Unaffected, and MSL 1 (Unlimited).

Q: Why is the SN74LS191D in Last Time Buy status?

A: Last Time Buy status indicates the manufacturer has discontinued production. Active substitutes (SN74LS191DR and SN74LS169BD) should be selected for new designs and ongoing production to ensure supply continuity.

Q: Can these parts be used interchangeably in PCB assembly?

A: Yes, provided the packaging format is compatible with your assembly process. SN74LS191DR (Cut Tape/Digi-Reel®) is optimized for automated pick-and-place assembly. SN74LS169BD (Tube) is suitable for manual or semi-automated assembly. The 16-SOIC package dimensions are identical across all three parts.