DM74ALS240ASJX Equivalent & Substitute Parts

Part Overview

The DM74ALS240ASJX is an inverting buffer logic integrated circuit manufactured by onsemi, featuring 2 elements with 4 bits per element and 3-state output capability. This device operates within the 74ALS logic family and is designed for applications requiring signal buffering and inversion in digital systems. The part is currently classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations.

Key Parameters

Parameter	Value
Manufacturer Part Number	DM74ALS240ASJX
Manufacturer	onsemi
Series	74ALS
Logic Type	Buffer, Inverting
Number of Elements	2
Number of Bits per Element	4
Output Type	3-State
Current - Output High, Low	15mA, 24mA
Voltage - Supply	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C (TA)
Mounting Type	Surface Mount
Package / Case	20-SOIC (0.209", 5.30mm Width)
Product Status	Obsolete
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the DM74ALS240ASJX is determined by strict equivalence across the following critical parameters:

Logic Type: Buffer, Inverting (2 elements, 4 bits per element)
Output Type: 3-State
Supply Voltage Range: 4.5V ~ 5.5V
Operating Temperature Range: 0°C ~ 70°C
Mounting Type: Surface Mount
Base Product Number: 74ALS240
Output Current Ratings: 15mA (High), 24mA (Low)

Substitute parts are grouped into two categories based on output current specifications:

Direct Electrical Equivalents (15mA High, 24mA Low): SN74ALS240ADW, SN74ALS240ADWR, SN74ALS240ANSR

Functional Equivalents with Enhanced Output Current (15mA High, 48mA Low): SN74ALS240A-1DW, SN74ALS240A-1NSR

All substitute parts maintain identical logic functionality, voltage specifications, temperature range, and element/bit configuration. Packaging variations (20-SOIC vs. 20-SO) and supplier formats (Tube, Tape & Reel, Cut Tape) do not affect electrical compatibility.

Parameter Comparison

Parameter	DM74ALS240ASJX (onsemi)	SN74ALS240ADW (TI)	SN74ALS240ADWR (TI)	SN74ALS240ANSR (TI)	SN74ALS240A-1DW (TI)	SN74ALS240A-1NSR (TI)
Logic Type	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting
Number of Elements	2	2	2	2	2	2
Number of Bits per Element	4	4	4	4	4	4
Output Type	3-State	3-State	3-State	3-State	3-State	3-State
Current - Output High, Low	15mA, 24mA	15mA, 24mA	15mA, 24mA	15mA, 24mA	15mA, 48mA	15mA, 48mA
Voltage - Supply	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

All Texas Instruments substitute parts (SN74ALS240ADW, SN74ALS240ADWR, SN74ALS240ANSR, SN74ALS240A-1DW, SN74ALS240A-1NSR) are classified as Active products with ROHS3 compliance, providing long-term availability and regulatory alignment compared to the obsolete onsemi DM74ALS240ASJX.

For applications requiring exact output current specifications (15mA High, 24mA Low), select from SN74ALS240ADW, SN74ALS240ADWR, or SN74ALS240ANSR. These parts maintain identical electrical performance to the original device.

For applications where enhanced output current capability (48mA Low) is acceptable or beneficial, SN74ALS240A-1DW and SN74ALS240A-1NSR provide increased drive capability while maintaining all other electrical parameters.

Packaging selection should be based on procurement and assembly requirements: 20-SOIC (0.295", 7.50mm Width) for SN74ALS240ADW and SN74ALS240ADWR, or 20-SOIC (0.209", 5.30mm Width) for SN74ALS240ANSR and SN74ALS240A-1NSR.

Frequently Asked Questions (FAQ)

Q: Can SN74ALS240A-1DW and SN74ALS240A-1NSR be used as direct replacements for DM74ALS240ASJX?

A: Yes. These parts are functionally equivalent. The increased output low current (48mA vs. 24mA) does not prevent substitution; it represents enhanced capability. Applications designed for 24mA output current will operate correctly with 48mA-rated devices.

Q: What is the difference between 20-SOIC (0.209", 5.30mm Width) and 20-SOIC (0.295", 7.50mm Width) packages?

A: Both are 20-pin SOIC packages with different body widths. The 0.209" width variant is narrower and may require different PCB footprints and assembly tooling. Verify PCB design compatibility before selecting a package variant.

Q: Are all substitute parts RoHS compliant?

A: Yes. All Texas Instruments substitute parts listed are ROHS3 compliant. The original onsemi DM74ALS240ASJX does not specify RoHS status.

Q: What is the significance of the product status difference (Obsolete vs. Active)?

A: Active products have guaranteed long-term availability and manufacturer support. Obsolete products may have limited stock and no future production. Substituting with Active products ensures supply chain continuity.

Q: Do packaging format differences (Tube, Tape & Reel, Cut Tape) affect electrical performance?

A: No. Packaging format affects only procurement, storage, and assembly processes. Electrical performance is identical across all packaging options for the same part number base.

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