SN74F21D Equivalent & Substitute Parts

Part Overview

The SN74F21D is a 2-channel AND gate logic IC manufactured by Texas Instruments in a 14-SOIC surface mount package. This component implements dual 4-input AND gate functions for digital logic applications. The SN74F21D carries a Last Time Buy status, indicating that Texas Instruments has discontinued active production. Finding equivalent substitute parts is necessary to ensure design continuity and maintain supply chain reliability for new production runs and long-term support.

Key Parameters

Parameter	Value
Manufacturer Part Number	SN74F21D
Manufacturer	Texas Instruments
Logic Type	AND Gate
Number of Circuits	2
Number of Inputs	4
Voltage - Supply	4.5V ~ 5.5V
Current - Quiescent (Max)	4.3 mA
Current - Output High, Low	1mA, 20mA
Input Logic Level - Low	0.8V
Input Logic Level - High	2V
Max Propagation Delay @ V, Max CL	5.1ns @ 5V, 50pF
Operating Temperature	0°C ~ 70°C
Package / Case	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Series	74F
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the SN74F21D is determined by strict equivalence across the following critical parameters:

Logic function: AND Gate with identical circuit count (2) and input configuration (4-input)
Electrical specifications: Supply voltage range (4.5V ~ 5.5V), quiescent current (4.3 mA max), output current ratings (1mA high, 20mA low), input logic levels (0.8V low, 2V high), and propagation delay (5.1ns @ 5V, 50pF)
Package compatibility: 14-SOIC surface mount package with identical physical dimensions (0.154", 3.90mm width)
Compliance standards: ROHS3 compliance and MSL rating of 1

The SN74F21DR qualifies as a direct substitute based on complete parameter alignment across all electrical, functional, and physical specifications. The only difference is packaging format: the SN74F21D is supplied in Tube packaging, while the SN74F21DR is supplied in Tape & Reel (TR) format. Both maintain identical performance characteristics and compliance certifications.

Parameter Comparison

Parameter	SN74F21D (Main Part)	SN74F21DR (Substitute)
Manufacturer	Texas Instruments	Texas Instruments
Logic Type	AND Gate	AND Gate
Number of Circuits	2	2
Number of Inputs	4	4
Voltage - Supply	4.5V ~ 5.5V	4.5V ~ 5.5V
Current - Quiescent (Max)	4.3 mA	4.3 mA
Current - Output High, Low	1mA, 20mA	1mA, 20mA
Input Logic Level - Low	0.8V	0.8V
Input Logic Level - High	2V	2V
Max Propagation Delay @ V, Max CL	5.1ns @ 5V, 50pF	5.1ns @ 5V, 50pF
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C
Package / Case	14-SOIC (0.154", 3.90mm Width)	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount	Surface Mount
Series	74F	74F
Product Status	Last Time Buy	Active
Packaging Format	Tube	Tape & Reel (TR)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

The SN74F21DR is the manufacturer-recommended substitute for the SN74F21D. Both parts are manufactured by Texas Instruments and maintain identical electrical performance, functional specifications, and compliance certifications. The SN74F21D is designated Last Time Buy, while the SN74F21DR carries Active product status, ensuring continued availability and supply chain support.

Selection between these parts should be based on packaging requirements. The SN74F21D is supplied in Tube packaging, suitable for lower-volume applications and manual assembly processes. The SN74F21DR is supplied in Tape & Reel format, optimized for high-volume automated assembly and pick-and-place manufacturing operations. Both parts are ROHS3 compliant with MSL rating of 1, meeting environmental and reliability standards for industrial and commercial applications.

Frequently Asked Questions (FAQ)

Q: Can the SN74F21DR be used as a direct replacement for the SN74F21D?

A: Yes. The SN74F21DR is electrically and functionally identical to the SN74F21D. All electrical parameters, logic specifications, and performance characteristics are equivalent. The parts differ only in packaging format: Tube versus Tape & Reel.

Q: What is the difference between Tube and Tape & Reel packaging?

A: Tube packaging supplies components in plastic tubes, typically used for manual assembly and lower-volume production. Tape & Reel packaging supplies components on continuous carrier tape wound on reels, optimized for automated pick-and-place assembly equipment and high-volume manufacturing. Both formats contain the same component with identical specifications.

Q: Are there any compatibility issues when switching from SN74F21D to SN74F21DR?

A: No compatibility issues exist. Both parts use the identical 14-SOIC package with the same pinout, electrical characteristics, and performance specifications. PCB layout and circuit design require no modification.

Q: Why is the SN74F21D marked as Last Time Buy?

A: Last Time Buy status indicates that Texas Instruments has discontinued active production of this part number. The SN74F21DR, with Active status, represents the current production equivalent and should be used for new designs and ongoing production requirements.

Q: Do both parts meet the same compliance standards?

A: Yes. Both the SN74F21D and SN74F21DR are ROHS3 compliant and carry MSL rating of 1 (Unlimited moisture sensitivity level). Both meet identical environmental and reliability standards.

Q: What is the operating temperature range for these parts?

A: Both parts operate across the temperature range of 0°C to 70°C, suitable for commercial and industrial applications.

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