SN74LS26D Equivalent & Substitute Parts

Part Overview

The SN74LS26D is a 4-channel 2-input NAND gate IC with open collector output in 14-SOIC surface mount packaging, manufactured by Texas Instruments. This logic component operates within the 74LS TTL family and is currently classified as Last Time Buy, indicating limited future availability. Identifying equivalent and substitute parts ensures design continuity and supply chain reliability for applications requiring NAND gate functionality with open collector characteristics.

Key Parameters

Parameter	Value
Logic Type	NAND Gate
Number of Circuits	4
Number of Inputs	2
Features	Open Collector
Voltage - Supply	4.75V ~ 5.25V
Current - Output High, Low	-, 8mA
Input Logic Level - Low	0.8V
Input Logic Level - High	2V
Max Propagation Delay @ V, Max CL	32ns @ 5V, 15pF
Operating Temperature	0°C ~ 70°C
Package / Case	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Series	74LS

Substitute Part Grouping Explanation

Substitution eligibility for the SN74LS26D is determined by the following critical parameters:

Logic Function: NAND gate with 4 channels and 2 inputs per channel
Output Configuration: Open collector topology
Supply Voltage Range: 4.75V ~ 5.25V compatibility
Input Logic Levels: Low threshold 0.8V, High threshold 2V
Package Type: 14-SOIC surface mount form factor
Propagation Delay: Maximum 32ns at 5V with 15pF load
Operating Temperature Range: 0°C ~ 70°C

Parts meeting these electrical and mechanical specifications are classified as direct substitutes. Variations in output current capability, quiescent current, or packaging format (tube vs. tape & reel) do not disqualify substitution but may affect application suitability based on specific design requirements.

Parameter Comparison

Parameter	SN74LS26D (Main)	SN74LS38D	SN74LS26DR	SN74LS03D
Manufacturer	Texas Instruments	onsemi	Texas Instruments	Texas Instruments
Logic Type	NAND Gate	NAND Gate	NAND Gate	NAND Gate
Number of Circuits	4	4	4	4
Number of Inputs	2	2	2	2
Features	Open Collector	Open Collector	Open Collector	Open Collector
Voltage - Supply	4.75V ~ 5.25V	4.75V ~ 5.25V	4.75V ~ 5.25V	4.75V ~ 5.25V
Current - Output Low	8mA	24mA	8mA	16mA
Input Logic Level - Low	0.8V	0.8V	0.8V	0.8V
Input Logic Level - High	2V	2V	2V	2V
Max Propagation Delay @ V, Max CL	32ns @ 5V, 15pF	32ns @ 5V, 45pF	32ns @ 5V, 15pF	32ns @ 5V, 15pF
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C
Package / Case	14-SOIC	14-SOIC	14-SOIC	14-SOIC
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Packaging Format	Tube	-	Tape & Reel	Tube
Product Status	Last Time Buy	Obsolete	Active	Last Time Buy
RoHS Status	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

SN74LS26DR is the primary recommended substitute. This part is manufactured by Texas Instruments (original manufacturer), maintains identical electrical specifications to the SN74LS26D, and carries Active product status ensuring continued availability. The SN74LS26DR is ROHS3 compliant and available in Tape & Reel packaging, suitable for high-volume production environments. This part represents the direct equivalent with superior supply chain positioning.

SN74LS03D is an alternative substitute manufactured by Texas Instruments with Last Time Buy status. Electrical parameters are compatible with the main part, with output current capability of 16mA (compared to 8mA in SN74LS26D). ROHS3 compliance and Tube packaging are provided. This part is suitable for applications where higher output current is beneficial, though supply availability is limited.

SN74LS38D is a functional substitute manufactured by onsemi with Obsolete product status. While electrical specifications align with substitution criteria, this part is RoHS non-compliant and carries higher output current (24mA) and quiescent current (2mA maximum). Selection of this part should be limited to legacy applications where RoHS compliance is not required and supply chain constraints necessitate its use.

Frequently Asked Questions (FAQ)

Q: Can SN74LS26DR directly replace SN74LS26D in existing designs?

A: Yes. The SN74LS26DR is electrically and mechanically identical to the SN74LS26D. The primary difference is packaging format (Tape & Reel vs. Tube) and product status (Active vs. Last Time Buy). Pin configuration, logic function, and electrical performance are equivalent.

Q: What is the significance of the output current difference between SN74LS26D (8mA) and SN74LS03D (16mA)?

A: Output current rating indicates the maximum current the open collector output can sink. The SN74LS03D's higher rating (16mA) provides greater drive capability for external loads. If the original design operates within 8mA limits, both parts are functionally compatible. Applications requiring higher current should verify load requirements against the selected part's rating.

Q: Why is SN74LS38D listed as a substitute if it is Obsolete and RoHS non-compliant?

A: SN74LS38D meets the core electrical and mechanical substitution criteria: 4-channel 2-input NAND gate with open collector output in 14-SOIC packaging. However, its Obsolete status and RoHS non-compliance make it unsuitable for new designs or applications with regulatory requirements. This part should only be considered for legacy system maintenance where supply constraints exist.

Q: Does packaging format (Tube vs. Tape & Reel) affect electrical performance?

A: No. Packaging format affects only handling, storage, and assembly processes. Electrical and functional performance is identical between Tube and Tape & Reel variants of the same part number base.

Q: Are all substitute parts ROHS3 compliant?

A: No. SN74LS38D is RoHS non-compliant. SN74LS26D, SN74LS26DR, and SN74LS03D are all ROHS3 compliant. For applications subject to RoHS regulations, SN74LS38D must be excluded from component selection.

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