74VHCT240ASJX Equivalent & Substitute Parts

Part Overview

The 74VHCT240ASJX is an inverting buffer logic IC manufactured by onsemi, featuring 2 elements with 4 bits per element and 3-state output capability. This component is classified as obsolete, making identification of active equivalent parts essential for ongoing design support and procurement continuity. The 74VHCT240 series provides buffering and signal inversion functions in digital logic applications requiring 5.5V operation and 3-state output control.

Key Parameters

Parameter	Value
Manufacturer Part Number	74VHCT240ASJX
Manufacturer	onsemi
Logic Type	Buffer, Inverting
Number of Elements	2
Number of Bits per Element	4
Output Type	3-State
Current - Output High, Low	8mA, 8mA
Voltage - Supply	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount
Package / Case	20-SOIC (0.209", 5.30mm Width)
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 74VHCT240ASJX is determined by the following critical parameters:

Logic Type: Buffer, Inverting (2 elements, 4 bits per element)
Output Type: 3-State
Output Current: 8mA high and low
Supply Voltage Range: 4.5V ~ 5.5V
Mounting Type: Surface Mount
RoHS Compliance: ROHS3 Compliant

The substitute parts listed below maintain functional equivalence through identical logic configuration, output characteristics, and supply voltage specifications. Package variations (20-SOIC, 20-SSOP, 20-SO) are mechanically compatible within the same footprint class and do not affect electrical performance. All substitutes are manufactured by Texas Instruments under the 74AHCT240 base product number and carry active or recently discontinued product status, ensuring superior availability compared to the obsolete onsemi part.

Parameter Comparison

Parameter	74VHCT240ASJX (onsemi)	SN74AHCT240DBR (TI)	SN74AHCT240DW (TI)	SN74AHCT240DWR (TI)	SN74AHCT240NSR (TI)
Logic Type	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting
Number of Elements	2	2	2	2	2
Number of Bits per Element	4	4	4	4	4
Output Type	3-State	3-State	3-State	3-State	3-State
Current - Output High, Low	8mA, 8mA	8mA, 8mA	8mA, 8mA	8mA, 8mA	8mA, 8mA
Voltage - Supply	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	20-SOIC (0.209", 5.30mm)	20-SSOP (0.209", 5.30mm)	20-SOIC (0.295", 7.50mm)	20-SOIC (0.295", 7.50mm)	20-SOIC (0.209", 5.30mm)
Product Status	Obsolete	Active	Discontinued at DiGi Electronics	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

All listed Texas Instruments substitutes meet the electrical and mechanical requirements for direct replacement of the 74VHCT240ASJX. Selection among the four alternatives should be based on the following criteria:

SN74AHCT240DWR is the primary recommended substitute. It maintains active product status with Texas Instruments, carries ROHS3 compliance, and is available in tape and reel packaging. The 20-SOIC package (0.295", 7.50mm width) is mechanically compatible with standard PCB layouts.

SN74AHCT240NSR provides an alternative with active status and identical electrical performance. The 20-SO package (0.209", 5.30mm width) offers a narrower footprint option while maintaining full functional equivalence.

SN74AHCT240DBR is available in active status with a 20-SSOP package (0.209", 5.30mm width), providing a compact surface-mount option suitable for space-constrained applications.

SN74AHCT240DW carries discontinued status at DiGi Electronics and should be considered only when other alternatives are unavailable. The 20-SOIC package (0.295", 7.50mm width) remains mechanically compatible.

All substitutes operate across the required -40°C to 125°C temperature range, exceeding the original part's -40°C to 85°C specification and providing enhanced thermal margin for demanding applications.

Frequently Asked Questions (FAQ)

Q: Can SN74AHCT240 series parts directly replace the 74VHCT240ASJX?

A: Yes. The SN74AHCT240 series maintains identical logic configuration (2 elements, 4 bits per element), 3-state output type, 8mA output current, and 4.5V to 5.5V supply voltage range. All electrical parameters required for functional equivalence are matched.

Q: What is the difference between the package options (20-SOIC, 20-SSOP, 20-SO)?

A: Package differences are mechanical only. The 20-SOIC (0.295", 7.50mm width) is the standard wide-body package. The 20-SSOP (0.209", 5.30mm width) and 20-SO (0.209", 5.30mm width) are narrower alternatives. All three are surface-mount packages with identical pin counts and electrical performance. PCB layout compatibility depends on the original design footprint.

Q: Why do the Texas Instruments substitutes have a higher operating temperature range (-40°C to 125°C vs. -40°C to 85°C)?

A: The extended temperature range of the SN74AHCT240 series reflects Texas Instruments' manufacturing and qualification standards. This provides additional thermal margin and is not a limitation for applications designed for the original -40°C to 85°C range.

Q: Are all substitutes RoHS compliant?

A: Yes. All listed substitutes carry ROHS3 compliance certification, matching the compliance status of the original 74VHCT240ASJX.

Q: Which substitute has the best availability?

A: SN74AHCT240DWR carries active product status with Texas Instruments and is available in tape and reel packaging, indicating strong ongoing production and distribution support.

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