74AC20SC NAND Gate IC Equivalent & Substitute Parts

Part Overview

The 74AC20SC is a dual 4-input NAND gate logic IC manufactured by onsemi in a 14-SOIC surface mount package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The 74AC20 series provides standard logic gating functionality suitable for digital circuit applications requiring NAND logic operations with moderate propagation delays and low quiescent current consumption.

Key Parameters

Parameter	Value
Logic Type	NAND Gate
Number of Circuits	2
Number of Inputs	4
Voltage Supply Range	2V ~ 6V
Package Type	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Operating Temperature	-40°C ~ 85°C
Max Propagation Delay	7ns @ 5V, 50pF

Substitute Part Grouping Explanation

Substitution eligibility for the 74AC20SC is determined by the following critical parameters: logic type (NAND gate), circuit count (2 channels), input count (4 inputs per channel), package type (14-SOIC), and mounting method (surface mount). All substitute parts listed maintain these core functional and physical specifications.

The substitute parts are grouped into two categories based on electrical performance characteristics:

Direct Manufacturer Equivalents (onsemi): MC74AC20DR2G and MC74AC20DG maintain identical electrical specifications to the 74AC20SC, including supply voltage range (2V ~ 6V), output current ratings (24mA), and propagation delay (7ns @ 5V, 50pF). These parts differ only in packaging format and product status.

Parametric Equivalents (Cross-Manufacturer): CD74AC20M (Harris Corporation) and CD74AC20M96 (Texas Instruments) provide functional equivalence with extended electrical operating ranges. These parts support a wider supply voltage range (1.5V ~ 5.5V) and extended temperature operation (-55°C ~ 125°C), with slightly increased propagation delay (12.2ns @ 5V, 50pF).

Parameter Comparison

Part Number	Manufacturer	Product Status	Voltage Supply	Quiescent Current (Max)	Output Current (High/Low)	Propagation Delay @ 5V, 50pF	Operating Temperature	Packaging	RoHS Status
74AC20SC	onsemi	Obsolete	2V ~ 6V	2 µA	24mA / 24mA	7ns	-40°C ~ 85°C	14-SOIC	REACH Unaffected
MC74AC20DR2G	onsemi	Active	2V ~ 6V	4 µA	24mA / 24mA	7ns	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
MC74AC20DG	onsemi	Active	2V ~ 6V	4 µA	24mA / 24mA	7ns	-40°C ~ 85°C	14-SOIC	ROHS3 Compliant
CD74AC20M	Harris Corporation	Obsolete	1.5V ~ 5.5V	4 µA	24mA / 24mA	12.2ns	-55°C ~ 125°C	14-SOIC	RoHS non-compliant
CD74AC20M96	Texas Instruments	Active	1.5V ~ 5.5V	4 µA	24mA / 24mA	12.2ns	-55°C ~ 125°C	14-SOIC	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement: MC74AC20DR2G and MC74AC20DG are the primary substitutes for 74AC20SC. Both are manufactured by onsemi with active product status and ROHS3 compliance. These parts maintain identical electrical performance specifications and 14-SOIC package compatibility. MC74AC20DR2G is supplied in Cut Tape and Digi-Reel packaging, while MC74AC20DG is supplied in Tube packaging. Selection between these two depends on procurement and assembly requirements.

For Extended Operating Range Applications: CD74AC20M96 (Texas Instruments) provides an active-status alternative with extended supply voltage (1.5V ~ 5.5V) and temperature range (-55°C ~ 125°C) capabilities. This part is suitable for applications requiring broader environmental operating conditions, though propagation delay increases to 12.2ns. ROHS3 compliance and unlimited moisture sensitivity level (MSL 1) support modern manufacturing standards.

Obsolete Part Consideration: CD74AC20M (Harris Corporation) is obsolete and RoHS non-compliant. This part should not be selected for new designs despite extended electrical specifications.

Frequently Asked Questions (FAQ)

Q: Can MC74AC20DR2G and MC74AC20DG be used interchangeably with 74AC20SC?

A: Yes. Both parts maintain identical electrical specifications (2V ~ 6V supply, 7ns propagation delay, 24mA output current) and 14-SOIC package dimensions. The difference is packaging format: MC74AC20DR2G uses Cut Tape/Digi-Reel, while MC74AC20DG uses Tube. Both are ROHS3 compliant and active products.

Q: What is the impact of using CD74AC20M96 instead of 74AC20SC?

A: CD74AC20M96 provides functional equivalence with trade-offs. Propagation delay increases from 7ns to 12.2ns, which may affect timing-critical circuits. Supply voltage range expands to 1.5V ~ 5.5V and operating temperature extends to -55°C ~ 125°C. The 14-SOIC package remains identical. This substitution is suitable only if timing specifications permit the increased delay.

Q: Are all substitute parts pin-compatible with 74AC20SC?

A: Yes. All listed substitutes use the 14-SOIC package with identical pinout and mechanical dimensions (0.154", 3.90mm width). Direct PCB replacement is possible without layout modification.

Q: Which substitute part offers the best compliance for modern manufacturing?

A: MC74AC20DR2G and MC74AC20DG (onsemi) and CD74AC20M96 (Texas Instruments) are all ROHS3 compliant with REACH Unaffected status. All three are suitable for current manufacturing standards. CD74AC20M should be avoided due to RoHS non-compliance.

Q: What is the difference between MC74AC20DR2G and MC74AC20DG?

A: Both parts are electrically identical with identical specifications. The difference is packaging: MC74AC20DR2G is supplied in Cut Tape and Digi-Reel format for automated assembly, while MC74AC20DG is supplied in Tube format for manual handling or lower-volume applications.

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