SN74LS122D Equivalent & Substitute Parts

Part Overview

The SN74LS122D is a monostable multivibrator logic IC manufactured by Texas Instruments, housed in a 14-SOIC surface mount package. This component generates a single output pulse of controlled duration when triggered by an input signal. The SN74LS122D is currently in Last Time Buy status, indicating that Texas Instruments has discontinued active production. Finding equivalent substitute parts is necessary to ensure continued availability for new designs, production runs, and maintenance applications where this component is specified.

Substiute Parts

SN74LS122D

Texas InstrumentsIn Stock: 1381SN74LS122D Datasheet

Current PartRFQ

SN74LS122DR

Texas InstrumentsIn Stock: 35689SN74LS122DR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74LS122D is determined by strict equivalence across the following critical parameters:

• Logic Function: Monostable multivibrator with identical circuit topology
• Propagation Delay: 28 ns (timing-critical parameter)
• Supply Voltage Range: 4.75 V ~ 5.25 V (5V logic standard)
• Output Current Specifications: 400µA high, 8mA low (drive capability)
• Package Type: 14-SOIC surface mount form factor
• Independent Circuits: Single circuit configuration
• Operating Temperature: 0°C ~ 70°C industrial range
• Compliance Standards: ROHS3, REACH Unaffected, EAR99 classification

The SN74LS122DR qualifies as a direct substitute because it maintains identical electrical specifications, functional behavior, and physical packaging while offering improved product status and availability.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS122DR is the direct equivalent substitute for the SN74LS122D. Both parts are manufactured by Texas Instruments and maintain identical electrical and functional specifications across all critical parameters. The primary distinction is product status: the SN74LS122D is in Last Time Buy phase, while the SN74LS122DR maintains Active status with significantly higher inventory availability (35,629 units versus 1,317 units).

Both parts carry ROHS3 compliance and REACH Unaffected status, ensuring regulatory alignment for current manufacturing standards. The packaging format differs (Tube versus Tape & Reel), which affects handling and assembly processes but does not impact electrical performance or physical compatibility in the 14-SOIC footprint.

For new designs and production applications, the SN74LS122DR is the preferred selection due to active product status and superior supply chain availability. For legacy system maintenance where the original SN74LS122D is specified, the SN74LS122DR provides pin-for-pin and functional equivalence.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS122DR be used as a direct replacement for the SN74LS122D in existing designs?

A: Yes. The SN74LS122DR is electrically and functionally identical to the SN74LS122D. Both parts share the same 14-SOIC package footprint, pinout, propagation delay (28 ns), supply voltage range (4.75 V ~ 5.25 V), and output current specifications. No circuit modifications are required.

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

A: Tube packaging (SN74LS122D) is used for lower-volume orders and manual handling. Tape & Reel packaging (SN74LS122DR) is designed for automated assembly equipment and high-volume production. The electrical component itself is identical; the difference is in packaging format and handling method.

Q: Why is the SN74LS122D in Last Time Buy status?

A: Last Time Buy status indicates that Texas Instruments has ended active production of this part number. Existing inventory is available for purchase, but no new manufacturing runs will occur. The SN74LS122DR remains in Active status and is the recommended alternative for future procurement.

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

A: No. Both the SN74LS122D and SN74LS122DR carry identical compliance certifications: ROHS3 Compliant, REACH Unaffected, Moisture Sensitivity Level 1 (Unlimited), and EAR99 export classification.

Q: What is the propagation delay specification, and why does it matter?

A: Propagation delay is 28 ns for both parts. This is the time required for the output to respond to an input trigger. This specification is critical for timing-sensitive applications and must remain constant across substitute parts to ensure circuit performance.

Q: Can I mix SN74LS122D and SN74LS122DR parts in the same production batch?

A: Yes. Since both parts are electrically and functionally identical, they can be used interchangeably within the same circuit design and production run. However, using a single part number (SN74LS122DR) is recommended for supply chain consistency and traceability.