DM74LS155N Equivalent & Substitute Parts

Part Overview

The DM74LS155N is a Decoder/Demultiplexer integrated circuit with 1 x 2:4 configuration, manufactured by onsemi in 24-DIP packaging. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance and new design implementations. The 74LS series decoder/demultiplexer function remains consistent across qualified substitutes, enabling direct functional replacement when electrical and mechanical parameters align.

Substiute Parts

DM74LS155N

onsemiIn Stock: 1996DM74LS155N Datasheet

Current PartRFQ

SN74LS155AN

Texas InstrumentsIn Stock: 1997SN74LS155AN Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the DM74LS155N is determined by the following critical parameters:

• Functional equivalence: Decoder/Demultiplexer type with 1 x 2:4 circuit configuration and 2 independent circuits
• Electrical compatibility: Identical output current specifications (400µA, 8mA), single supply voltage source, and supply voltage range (4.75V ~ 5.25V)
• Operating conditions: Matching operating temperature range (0°C ~ 70°C)
• Logic series: 74LS series compatibility
• Mounting technology: Through-hole mounting requirement

The SN74LS155AN from Texas Instruments meets all functional and electrical criteria for substitution. However, a package difference exists: the substitute uses 16-DIP packaging versus the original 24-DIP packaging. This difference requires mechanical evaluation for board layout compatibility.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS155AN qualifies as a functional substitute based on matching electrical specifications, circuit configuration, and logic series classification. The substitute part carries Active product status from Texas Instruments, ensuring ongoing availability and support compared to the obsolete DM74LS155N.

The primary consideration for selection is the package difference: 16-DIP versus 24-DIP. The SN74LS155AN occupies a smaller footprint (0.300" versus 0.600" body width), which may require PCB layout modification. Pin-to-pin functional equivalence must be verified against the specific application schematic before implementation.

The SN74LS155AN holds ROHS3 compliance status, providing environmental regulatory alignment for new designs. Both parts maintain REACH Unaffected status and EAR99 export classification.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS155AN directly replace the DM74LS155N without circuit modification?

A: Functional replacement is possible due to identical electrical specifications and circuit configuration. However, the package difference (16-DIP versus 24-DIP) requires PCB layout evaluation. Pin assignments must be cross-referenced with application documentation to confirm compatibility.

Q: What is the significance of the package size difference?

A: The DM74LS155N uses 24-DIP packaging (0.600" body width), while the SN74LS155AN uses 16-DIP packaging (0.300" body width). This affects board footprint, hole spacing, and component placement. Existing PCB designs may require layout modification to accommodate the smaller package.

Q: Why is the DM74LS155N classified as obsolete?

A: Obsolete status indicates the manufacturer (onsemi) has discontinued production. The SN74LS155AN from Texas Instruments remains in active production, making it the preferred choice for new applications and ongoing system support.

Q: Are the electrical characteristics identical between these parts?

A: Yes. Both parts share identical output current specifications (400µA, 8mA), supply voltage range (4.75V ~ 5.25V), operating temperature range (0°C ~ 70°C), and circuit configuration (1 x 2:4 decoder/demultiplexer with 2 independent circuits).

Q: What compliance certifications apply to the substitute part?

A: The SN74LS155AN holds ROHS3 compliance and REACH Unaffected status, meeting current environmental and regulatory requirements for electronic components.