DM74LS85N Equivalent & Substitute Parts

Part Overview

The DM74LS85N is a 4-bit magnitude comparator logic IC manufactured by onsemi, housed in a 16-pin DIP package. This device performs magnitude comparison operations with active high outputs for A<B, A=B, and A>B functions. The DM74LS85N is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement.

Substiute Parts

DM74LS85N

onsemiIn Stock: 1512DM74LS85N Datasheet

Current PartRFQ

SN74LS85N

Texas InstrumentsIn Stock: 19771SN74LS85N Datasheet

DirectRFQ

CD4063BE

Harris CorporationIn Stock: 2040CD4063BE Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the DM74LS85N are identified based on the following critical parameters that determine functional compatibility:

Core Compatibility Criteria:

• Number of Bits: 4-bit magnitude comparison function
• Output Type: Active High outputs
• Output Function: A<B, A=B, A>B comparison outputs
• Package / Case: 16-DIP (0.300", 7.62mm)
• Mounting Type: Through Hole

Substitution Categories:

Direct Substitute (Pin-Compatible, Voltage-Compatible): SN74LS85N maintains identical electrical specifications within the 4.75V ~ 5.25V supply range, same output characteristics, and identical pinout. This part is suitable for direct replacement in applications requiring TTL-level logic operation.

Similar Substitute (Functional Equivalent, Extended Operating Range): CD4063BE provides the same 4-bit magnitude comparison functionality and 16-DIP package configuration. However, this part operates across an extended supply voltage range (3V ~ 18V) and extended temperature range (-55°C ~ 125°C), making it suitable for applications requiring broader environmental tolerance. Propagation delay characteristics differ significantly due to CMOS technology versus TTL technology.

Parameter Comparison

Engineering Selection Recommendations

SN74LS85N (Direct Substitute - Recommended for Standard Applications): The SN74LS85N is the primary substitute for the DM74LS85N. Both parts operate within identical voltage and temperature ranges, maintain equivalent output current specifications, and share the same pinout. The SN74LS85N is currently in active production status with ROHS3 compliance, providing long-term availability and regulatory alignment for new designs. Propagation delay is marginally higher (45ns versus 42ns), which is negligible for most comparison applications.

CD4063BE (Alternative Substitute - For Extended Environmental Requirements): The CD4063BE functions as a 4-bit magnitude comparator with identical output logic and package configuration. This part is suitable only for applications requiring extended supply voltage range (3V ~ 18V) or extended temperature operation (-55°C ~ 125°C). The significantly longer propagation delay (350ns) makes this part unsuitable for high-speed comparison applications. Both the DM74LS85N and CD4063BE are obsolete; however, CD4063BE inventory availability may differ.

Frequently Asked Questions (FAQ)

Q: Can SN74LS85N directly replace DM74LS85N without circuit modification? A: Yes. The SN74LS85N is pin-compatible and electrically equivalent within the specified voltage and temperature ranges. No circuit modifications are required for direct substitution in standard 5V logic applications.

Q: What are the key differences between SN74LS85N and CD4063BE? A: Both parts perform 4-bit magnitude comparison in 16-DIP packages. SN74LS85N operates at 4.75V ~ 5.25V with 42-45ns propagation delay, suitable for TTL-level systems. CD4063BE operates at 3V ~ 18V with 350ns propagation delay, suitable for extended voltage range applications but not for high-speed comparison requirements.

Q: Is the CD4063BE suitable as a drop-in replacement for the DM74LS85N? A: The CD4063BE is functionally equivalent but not a direct drop-in replacement. It requires different supply voltage considerations and exhibits significantly longer propagation delay. Use CD4063BE only when extended voltage range or temperature operation is a design requirement.

Q: What is the impact of the propagation delay difference between DM74LS85N (42ns) and SN74LS85N (45ns)? A: The 3ns difference is negligible for most comparison applications. Both parts meet standard TTL timing specifications. Verify timing requirements only if the application operates at frequencies exceeding 20 MHz or requires sub-50ns comparison resolution.

Q: Are there RoHS compliance considerations for substitute selection? A: SN74LS85N is ROHS3 compliant, making it suitable for applications with RoHS regulatory requirements. DM74LS85N and CD4063BE are both RoHS non-compliant. For new designs subject to RoHS regulations, SN74LS85N is the appropriate selection.

Q: Can both substitute parts be used interchangeably in the same design? A: No. SN74LS85N and CD4063BE have different electrical characteristics and operating ranges. Select one based on specific application requirements. Mixing these parts in the same system is not recommended due to timing and voltage compatibility differences.