74ACT240SJX Equivalent & Substitute Parts

Part Overview

The 74ACT240SJX is a Buffer, Inverting logic IC manufactured by onsemi, featuring 2 elements with 4 bits per element and 3-state output capability. This component operates across a 4.5V to 5.5V supply voltage range and is rated for -40°C to 85°C operating temperature. The part is currently classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Base Product Number	74ACT240
Logic Type	Buffer, Inverting
Number of Elements	2
Number of Bits per Element	4
Output Type	3-State
Current - Output High, Low	24mA, 24mA
Voltage - Supply	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount
Series	74ACT

Substitute Part Grouping Explanation

Substitution for the 74ACT240SJX is determined by strict equivalence across the following electrical and mechanical parameters:

Base product number (74ACT240)
Logic type (Buffer, Inverting)
Number of elements (2) and bits per element (4)
Output type (3-State)
Output current specifications (24mA, 24mA)
Supply voltage range (4.5V ~ 5.5V)
Operating temperature range (-40°C ~ 85°C)
Mounting type (Surface Mount)

Package variations are permitted within the 74ACT240 family, as the electrical functionality remains identical across different package types. Substitute parts maintain all core electrical parameters while differing in physical packaging, supplier device package designation, or product status.

Parameter Comparison

Part Number	Manufacturer	Package / Case	Product Status	Logic Type	Output Current (mA)	Supply Voltage	Operating Temp
74ACT240SJX	onsemi	20-SOIC (0.209", 5.30mm)	Obsolete	Buffer, Inverting	24, 24	4.5V ~ 5.5V	-40°C ~ 85°C
74ACT240MTCX	onsemi	20-TSSOP (0.173", 4.40mm)	Active	Buffer, Inverting	24, 24	4.5V ~ 5.5V	-40°C ~ 85°C
74ACT240SCX	Fairchild Semiconductor	20-SOIC (0.295", 7.50mm)	Active	Buffer, Inverting	24, 24	4.5V ~ 5.5V	-40°C ~ 85°C
CD74ACT240M	Harris Corporation	20-SOIC (0.295", 7.50mm)	Obsolete	Buffer, Inverting	24, 24	4.5V ~ 5.5V	-40°C ~ 85°C
CD74ACT240M96	Texas Instruments	20-SOIC (0.295", 7.50mm)	Active	Buffer, Inverting	24, 24	4.5V ~ 5.5V	-40°C ~ 85°C
SN74ACT240DWR	Texas Instruments	20-SOIC (0.295", 7.50mm)	Active	Buffer, Inverting	24, 24	4.5V ~ 5.5V	-40°C ~ 85°C
SN74ACT240NSR	Texas Instruments	20-SOIC (0.209", 5.30mm)	Active	Buffer, Inverting	24, 24	4.5V ~ 5.5V	-40°C ~ 85°C

Engineering Selection Recommendations

For applications requiring the 74ACT240SJX, the following selection criteria apply:

Active Product Status Priority: SN74ACT240NSR, SN74ACT240DWR, CD74ACT240M96, 74ACT240MTCX, and 74ACT240SCX are all active products with current manufacturing support. These parts are preferred for new designs and ongoing procurement.

Package Compatibility: The SN74ACT240NSR maintains the identical 20-SOIC (0.209", 5.30mm) package as the original 74ACT240SJX, providing direct board-level compatibility without PCB redesign. This part is manufactured by Texas Instruments and carries ROHS3 compliance.

Alternative Package Options: The 74ACT240MTCX offers a narrower 20-TSSOP package (0.173", 4.40mm width) for space-constrained applications. The SN74ACT240DWR and CD74ACT240M96 provide 20-SOIC packages with wider 0.295" and 7.50mm dimensions, suitable for applications where package width is not a constraint.

Compliance Considerations: Parts with ROHS3 compliance (SN74ACT240NSR, SN74ACT240DWR, CD74ACT240M96, 74ACT240MTCX) are recommended for applications subject to RoHS regulations. The CD74ACT240M is RoHS non-compliant and should be avoided in regulated environments.

Frequently Asked Questions (FAQ)

Q: Can I directly replace the 74ACT240SJX with any of these substitute parts?

A: Direct replacement depends on package compatibility. The SN74ACT240NSR is the closest match, maintaining the identical 20-SOIC (0.209", 5.30mm) package. Other substitutes require PCB layout verification due to different package dimensions.

Q: What is the difference between 20-SOIC and 20-TSSOP packages?

A: Both are surface-mount packages with 20 pins. The 20-SOIC (0.209" or 0.295" width) has larger pin spacing suitable for standard PCB assembly. The 20-TSSOP (0.173" width) is a thinner shrink package for space-constrained designs. Pin pitch and footprint differ between these packages.

Q: Are all substitute parts electrically identical to the 74ACT240SJX?

A: Yes. All listed substitute parts maintain identical electrical specifications: 2-element, 4-bit buffer with inverting logic, 3-state output, 24mA output current, 4.5V to 5.5V supply voltage, and -40°C to 85°C operating temperature range.

Q: Which substitute should I choose for new designs?

A: For new designs, select from active products: SN74ACT240NSR (Texas Instruments, identical package), 74ACT240MTCX (onsemi, compact TSSOP), or SN74ACT240DWR (Texas Instruments, standard SOIC). All three carry ROHS3 compliance and current manufacturing support.

Q: Does the 74ACT240SJX have any moisture sensitivity concerns?

A: No. The 74ACT240SJX and all listed substitutes carry Moisture Sensitivity Level (MSL) 1, indicating unlimited shelf life without moisture control requirements.

Q: What is the difference between "Similar" and "Parametric Equivalent" substitutes?

A: All listed parts are functionally equivalent based on electrical parameters. The SN74ACT240NSR is specifically designated as a parametric equivalent, maintaining the original package dimensions. Other parts are similar substitutes with identical electrical function but different packaging options.

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