74HC21N Equivalent & Substitute Parts

Part Overview

The 74HC21N is a dual 4-input AND gate logic IC manufactured by NXP USA Inc. in a 14-DIP package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance and new designs requiring this logic function. The 74HC21N operates across a 2V to 6V supply voltage range and is suitable for digital logic applications requiring AND gate functionality with two independent channels.

Key Parameters

Parameter	Value
Logic Type	AND Gate
Number of Circuits	2
Number of Inputs	4
Voltage - Supply	2V ~ 6V
Current - Quiescent (Max)	2 µA
Current - Output High, Low	5.2mA, 5.2mA
Input Logic Level - Low	0.5V ~ 1.8V
Input Logic Level - High	1.5V ~ 4.2V
Max Propagation Delay @ 6V, 50pF	19ns
Operating Temperature	-40°C ~ 125°C
Mounting Type	Through Hole
Package / Case	14-DIP (0.300", 7.62mm)
Series	74HC

Substitute Part Grouping Explanation

Substitute parts for the 74HC21N are qualified based on the following criteria:

Identical logic function: dual 4-input AND gate
Matching circuit count: 2 channels
Matching input count: 4 inputs per channel
Compatible supply voltage range: 2V ~ 6V
Equivalent electrical characteristics: quiescent current, output current, propagation delay, and logic level thresholds
Compatible package: 14-DIP form factor with 0.300" (7.62mm) pitch
Through-hole mounting compatibility

The following parts meet these substitution criteria and are listed in the 74HC series family.

Parameter Comparison

Parameter	74HC21N (NXP)	CD74HC21E (Harris)	SN74HC21N (Texas Instruments)
Manufacturer	NXP USA Inc.	Harris Corporation	Texas Instruments
Logic Type	AND Gate	AND Gate	AND Gate
Number of Circuits	2	2	2
Number of Inputs	4	4	4
Voltage - Supply	2V ~ 6V	2V ~ 6V	2V ~ 6V
Current - Quiescent (Max)	2 µA	2 µA	2 µA
Current - Output High, Low	5.2mA, 5.2mA	5.2mA, 5.2mA	5.2mA, 5.2mA
Input Logic Level - Low	0.5V ~ 1.8V	0.5V ~ 1.8V	0.5V ~ 1.8V
Input Logic Level - High	1.5V ~ 4.2V	1.5V ~ 4.2V	1.5V ~ 4.2V
Max Propagation Delay @ 6V, 50pF	19ns	19ns	19ns
Operating Temperature	-40°C ~ 125°C	-55°C ~ 125°C	-40°C ~ 85°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	14-DIP (0.300", 7.62mm)	14-DIP (0.300", 7.62mm)	14-DIP (0.300", 7.62mm)
Product Status	Obsolete	Obsolete	Active
RoHS Status	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

SN74HC21N (Texas Instruments) is the primary substitute for new designs and ongoing applications. This part maintains active product status, ensuring long-term availability and supply chain stability. It is ROHS3 compliant and meets environmental regulatory requirements. The operating temperature range of -40°C to 85°C covers standard industrial and commercial applications. All electrical parameters are identical to the 74HC21N.

CD74HC21E (Harris Corporation) is a functional equivalent with identical electrical characteristics and an extended operating temperature range of -55°C to 125°C, suitable for extended-temperature applications. However, this part is obsolete and RoHS non-compliant, limiting its use to legacy system maintenance where regulatory compliance is not required.

74HC21N (NXP USA Inc.) remains available in current inventory (800 pieces) with ROHS3 compliance and standard operating temperature range. Selection depends on supply chain requirements and regulatory compliance mandates.

Frequently Asked Questions (FAQ)

Q: Can SN74HC21N directly replace 74HC21N in existing designs? A: Yes. The SN74HC21N is a direct functional substitute with identical electrical specifications, logic function, and 14-DIP package configuration. Pin-for-pin compatibility is maintained.

Q: What is the difference between 14-DIP and 14-PDIP packaging? A: Both designations refer to 14-pin dual in-line packages with 0.300" (7.62mm) pitch. The terms are used interchangeably in industry documentation. Physical dimensions and pin spacing are identical.

Q: Is CD74HC21E suitable for new production designs? A: CD74HC21E is not recommended for new production due to obsolete status and RoHS non-compliance. Use SN74HC21N for new designs requiring active product status and regulatory compliance.

Q: What are the key parameters that determine substitutability? A: Substitutability is determined by: logic function (dual 4-input AND gate), circuit count (2), input count (4), supply voltage range (2V ~ 6V), electrical characteristics (quiescent current, output current, propagation delay, logic levels), package type (14-DIP), and mounting method (through-hole).

Q: Does operating temperature range affect substitution? A: Operating temperature range does not prevent substitution if the application operates within the substitute part's specified range. SN74HC21N (-40°C to 85°C) covers standard industrial applications. CD74HC21E (-55°C to 125°C) is required only for extended-temperature environments.

Q: Are all three parts electrically interchangeable? A: Yes, all three parts are electrically interchangeable within their respective operating temperature ranges. Differences exist only in product status, compliance certifications, and temperature ratings.

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