SN74LS221D Equivalent & Substitute Parts

Part Overview

The SN74LS221D is a monostable multivibrator logic IC manufactured by Texas Instruments, housed in a 16-SOIC surface mount package. This component generates precise timing pulses and is commonly used in digital timing and pulse generation applications. The SN74LS221D carries a Last Time Buy status, indicating that Texas Instruments has discontinued active production. This status necessitates identifying functionally equivalent substitute parts to ensure design continuity and procurement availability for new builds and ongoing production requirements.

Substiute Parts

SN74LS221D

Texas InstrumentsIn Stock: 1308SN74LS221D Datasheet

Current PartRFQ

SN74LS221DR

Texas InstrumentsIn Stock: 5140SN74LS221DR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74LS221D is determined by strict equivalence across the following critical parameters:

• Logic Type: Monostable Multivibrator with 2 independent circuits
• Propagation Delay: 45 ns
• Current Specifications: Output High 400µA, Output Low 8mA
• Supply Voltage Range: 4.75 V ~ 5.25 V
• Operating Temperature Range: 0°C ~ 70°C
• Package Configuration: 16-SOIC surface mount
• Electrical Compliance: ROHS3 Compliant, REACH Unaffected

The SN74LS221DR qualifies as a direct substitute based on identical electrical characteristics, functional specifications, and package geometry. The primary distinction is packaging format and product status, not electrical performance.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS221DR is the primary substitute for the SN74LS221D. Both parts are manufactured by Texas Instruments and maintain identical electrical and functional specifications across all critical parameters. The SN74LS221DR carries Active product status, ensuring ongoing availability and supply chain continuity compared to the Last Time Buy status of the SN74LS221D.

Both parts meet ROHS3 compliance and REACH requirements, making them suitable for applications with environmental and regulatory constraints. The difference in packaging format (Tube versus Cut Tape & Digi-Reel) does not affect electrical performance and is determined by procurement and assembly requirements.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS221DR be used as a direct replacement for the SN74LS221D?

A: Yes. Both parts are electrically and functionally identical. They share the same propagation delay (45 ns), output current specifications (400µA, 8mA), supply voltage range (4.75 V ~ 5.25 V), operating temperature range (0°C ~ 70°C), and 16-SOIC package configuration. No circuit modifications are required.

Q: What is the difference between the SN74LS221D and SN74LS221DR?

A: The primary differences are product status and packaging format. The SN74LS221D is Last Time Buy with Tube packaging, while the SN74LS221DR is Active with Cut Tape & Digi-Reel packaging. Electrical performance is identical.

Q: Why is the SN74LS221D marked as Last Time Buy?

A: Last Time Buy status indicates that Texas Instruments has discontinued active production of this part number. Existing inventory may be available through authorized distributors, but long-term availability is not guaranteed. The SN74LS221DR should be used for new designs and ongoing production.

Q: Are there any compatibility concerns when switching from SN74LS221D to SN74LS221DR?

A: No compatibility concerns exist. Both parts use the identical 16-SOIC package footprint and pinout. PCB layout and assembly processes require no modification.

Q: Do both parts meet the same compliance standards?

A: Yes. Both the SN74LS221D and SN74LS221DR are ROHS3 Compliant and REACH Unaffected, meeting the same environmental and regulatory requirements.