DM74ALS240ASJ Equivalent & Substitute Parts

Part Overview

The DM74ALS240ASJ is a logic buffer IC with inverting functionality, featuring 2 elements with 4 bits per element and 3-state output capability. Manufactured by onsemi in a 20-SOP package, this component operates across a 4.5V to 5.5V supply voltage range and is rated for 0°C to 70°C operating temperature. The part is currently obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Logic Type	Buffer, Inverting
Number of Elements	2
Number of Bits per Element	4
Output Type	3-State
Current - Output High	15mA
Current - Output Low	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)
Series	74ALS
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the DM74ALS240ASJ is determined by strict equivalence across the following parameters: logic type (Buffer, Inverting), number of elements (2), bits per element (4), output type (3-State), supply voltage range (4.5V ~ 5.5V), operating temperature range (0°C ~ 70°C), and series classification (74ALS). All identified substitute parts maintain these core electrical specifications. Packaging variations (20-SO versus 20-SOIC) and output current specifications are secondary considerations that do not affect functional substitution within the same PCB footprint family. Product status transition from obsolete to active availability is a key advantage of these alternatives.

Parameter Comparison

Parameter	DM74ALS240ASJ (onsemi)	SN74ALS240ANSR (TI)	SN74ALS240A-1DW (TI)	SN74ALS240A-1NSR (TI)	SN74ALS240ADW (TI)	SN74ALS240ADWR (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, 48mA	15mA, 48mA	15mA, 24mA	15mA, 24mA
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 (TA)	0°C ~ 70°C (TA)	0°C ~ 70°C (TA)	0°C ~ 70°C (TA)	0°C ~ 70°C (TA)	0°C ~ 70°C (TA)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	20-SOIC (0.209", 5.30mm Width)	20-SOIC (0.209", 5.30mm Width)	20-SOIC (0.295", 7.50mm Width)	20-SOIC (0.209", 5.30mm Width)	20-SOIC (0.295", 7.50mm Width)	20-SOIC (0.295", 7.50mm Width)
Series	74ALS	74ALS	74ALS	74ALS	74ALS	74ALS
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 five Texas Instruments substitute parts maintain full electrical and functional equivalence to the DM74ALS240ASJ across core logic specifications. Selection among these alternatives should be based on packaging format and output current requirements:

For designs requiring the original 0.209" package width, SN74ALS240ANSR and SN74ALS240A-1NSR are direct footprint matches. SN74ALS240ANSR is supplied in Tape & Reel format with 4,930 units in stock, while SN74ALS240A-1NSR is also Tape & Reel packaged with 3,155 units available. Both maintain 15mA/24mA output current specifications matching the original part.

For designs accommodating the 0.295" package width, SN74ALS240ADW and SN74ALS240ADWR provide alternatives with 1,545 and 2,938 units in stock respectively, both maintaining 15mA/24mA output current. SN74ALS240A-1DW offers the same package width with higher output current capability (15mA/48mA) and 1,663 units available.

All substitute parts carry ROHS3 compliance and REACH Unaffected status, supporting modern regulatory requirements. The transition from obsolete to active product status ensures long-term availability and supply chain stability.

Frequently Asked Questions (FAQ)

Q: Can SN74ALS240A-1DW and SN74ALS240A-1NSR be used interchangeably with the DM74ALS240ASJ?

A: Both parts are functionally equivalent in logic operation. SN74ALS240A-1NSR maintains identical package dimensions (0.209" width) and output current (15mA/24mA) as the original. SN74ALS240A-1DW uses a wider package (0.295" width) and higher output current (15mA/48mA), requiring PCB layout verification before substitution.

Q: What is the difference between 20-SO and 20-SOIC package designations?

A: Both designations refer to 20-pin surface-mount packages. The primary distinction is package width: 0.209" (narrow) versus 0.295" (wide). Footprint compatibility must be confirmed with PCB design specifications before part selection.

Q: Are all substitute parts RoHS compliant?

A: All five Texas Instruments alternatives carry ROHS3 Compliant certification. The original DM74ALS240ASJ does not specify RoHS status in available documentation.

Q: What is the significance of output current differences (15mA/24mA versus 15mA/48mA)?

A: Output current specifications define the maximum current the IC can source (high) or sink (low) at its outputs. Parts rated 15mA/24mA are suitable for standard logic-level loads. Parts rated 15mA/48mA provide higher current sinking capability for applications requiring increased drive strength. Selection depends on downstream load requirements.

Q: Which substitute part offers the best inventory availability?

A: SN74ALS240ANSR provides the highest stock level with 4,930 units available, followed by SN74ALS240ADWR with 2,938 units. Both are active products with established supply chains.

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