MM74HCT240SJX Equivalent & Substitute Parts

Part Overview

The MM74HCT240SJX is a 74HCT series inverting buffer logic IC manufactured by onsemi, featuring 2 elements with 4 bits per element and 3-state output capability. This surface-mount device operates across a 4.5V to 5.5V supply range and is rated for -40°C to 85°C operating temperature. The part is currently listed as obsolete, making equivalent substitutes necessary for ongoing design support and procurement.

Substiute Parts

MM74HCT240SJX

onsemiIn Stock: 1228MM74HCT240SJX Datasheet

Current PartRFQ

CD74HCT240M

Harris CorporationIn Stock: 1264CD74HCT240M Datasheet

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CD74HCT240M96

Texas InstrumentsIn Stock: 1074CD74HCT240M96 Datasheet

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SN74HCT240DW

Texas InstrumentsIn Stock: 2142SN74HCT240DW Datasheet

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SN74HCT240DWR

Texas InstrumentsIn Stock: 3260SN74HCT240DWR Datasheet

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SN74HCT240NSR

Texas InstrumentsIn Stock: 4721SN74HCT240NSR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MM74HCT240SJX is determined by the following critical parameters:

• Logic Function: Buffer, Inverting with 2 elements and 4 bits per element
• Output Configuration: 3-State output capability
• Supply Voltage Range: 4.5V ~ 5.5V compatibility
• Mounting Type: Surface mount technology
• Package Compatibility: 20-pin SOIC or equivalent footprint

All substitute parts listed maintain the core 74HCT240 base product number and identical logic functionality. Variations in output current ratings (6mA vs 7.2mA), operating temperature ranges, and package dimensions are secondary considerations that do not affect functional substitution within the specified electrical parameters.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: SN74HCT240DWR

The SN74HCT240DWR is the preferred substitute for the MM74HCT240SJX. This Texas Instruments part maintains active product status, ensuring long-term availability and supply chain stability. It carries ROHS3 compliance and matches the original operating temperature range of -40°C to 85°C. The 20-SOIC package with 0.295" width accommodates standard PCB layouts, and the 6mA output current specification remains within acceptable design margins for most applications.

Secondary Recommendation: SN74HCT240NSR

The SN74HCT240NSR offers identical electrical performance to the primary recommendation with active product status. This part features the narrower 20-SOIC package (0.209" width) matching the original MM74HCT240SJX footprint, eliminating potential PCB layout modifications. ROHS3 compliance and MSL 1 rating confirm environmental and handling compatibility.

Alternative Option: CD74HCT240M96

The CD74HCT240M96 provides the widest operating temperature range (-55°C to 125°C) among available substitutes, suitable for extended-temperature applications. Active product status and ROHS3 compliance support procurement continuity. The wider 20-SOIC package (0.295") requires PCB layout verification.

Not Recommended: CD74HCT240M

While functionally equivalent, the CD74HCT240M carries RoHS non-compliant status and obsolete product designation, limiting its suitability for new designs or regulated applications.

Frequently Asked Questions (FAQ)

Q: Can the SN74HCT240DWR directly replace the MM74HCT240SJX on existing PCBs?

A: The SN74HCT240DWR maintains electrical compatibility and operates within the same supply voltage and temperature ranges. However, the package width differs (0.295" vs 0.209"), requiring PCB footprint verification. If the original PCB accommodates the wider 20-SOIC package, direct substitution is feasible. For space-constrained layouts, the SN74HCT240NSR with matching 0.209" width is preferred.

Q: What is the significance of the 6mA vs 7.2mA output current difference?

A: The MM74HCT240SJX specifies 7.2mA output current, while substitute parts specify 6mA. This difference does not affect functional compatibility in standard logic applications. The 6mA rating remains sufficient for driving typical TTL/CMOS loads. Applications requiring maximum output current should confirm load impedance compatibility during design review.

Q: Are all substitute parts RoHS compliant?

A: Four of five substitute parts carry ROHS3 compliance certification. The CD74HCT240M is RoHS non-compliant and should not be used in applications requiring regulatory compliance. For new designs, select from SN74HCT240DWR, SN74HCT240NSR, or CD74HCT240M96.

Q: Which substitute offers the best long-term availability?

A: The SN74HCT240DWR and SN74HCT240NSR both carry active product status from Texas Instruments, ensuring continued manufacturing and supply chain support. The CD74HCT240M96 also maintains active status. These three parts are recommended for designs requiring extended product lifecycle support.

Q: Does package width affect circuit performance?

A: Package width (0.209" vs 0.295") is a physical footprint consideration only and does not affect electrical performance. Selection depends on PCB layout constraints. Verify that the selected package width accommodates existing or planned PCB designs before procurement.