74AC540SC Equivalent & Substitute Parts

Part Overview

The 74AC540SC is an inverting buffer logic integrated circuit manufactured by onsemi, designed for 3-state output applications in the 74AC series. This component features 1 element with 8 bits per element, operating across a supply voltage range of 2V to 6V with 24mA output current capability in both high and low states. The 74AC540SC is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Manufacturer Part Number	74AC540SC
Manufacturer	onsemi
Logic Type	Buffer, Inverting
Number of Elements	1
Number of Bits per Element	8
Output Type	3-State
Current - Output High, Low	24mA, 24mA
Voltage - Supply	2V ~ 6V
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	20-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the 74AC540SC are identified based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Logic Type: Buffer, Inverting (identical function)
Number of Elements: 1 (identical configuration)
Number of Bits per Element: 8 (identical bit width)
Output Type: 3-State (identical output architecture)
Current - Output High, Low: 24mA, 24mA (identical drive capability)
Package / Case: 20-SOIC (identical physical footprint)
Mounting Type: Surface Mount (identical assembly method)

Substitute parts are grouped into two categories based on electrical operating ranges:

Group 1 (Extended Supply Range): MC74AC540DWG and MC74AC540DWR2G operate within 2V ~ 6V supply voltage, matching the 74AC540SC specification exactly.

Group 2 (Wider Operating Range): CD74AC540M and CD74AC540M96 operate within 1.5V ~ 5.5V supply voltage with extended temperature range (-55°C ~ 125°C), providing broader environmental compatibility while maintaining core functional equivalence.

Parameter Comparison

Parameter	74AC540SC	MC74AC540DWG	MC74AC540DWR2G	CD74AC540M	CD74AC540M96
Manufacturer	onsemi	onsemi	onsemi	Harris Corporation	Texas Instruments
Logic Type	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting
Number of Elements	1	1	1	1	1
Number of Bits per Element	8	8	8	8	8
Output Type	3-State	3-State	3-State	3-State	3-State
Current - Output High, Low	24mA, 24mA	24mA, 24mA	24mA, 24mA	24mA, 24mA	24mA, 24mA
Voltage - Supply	2V ~ 6V	2V ~ 6V	2V ~ 6V	1.5V ~ 5.5V	1.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-55°C ~ 125°C	-55°C ~ 125°C
Package / Case	20-SOIC	20-SOIC	20-SOIC	20-SOIC	20-SOIC
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Obsolete	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

For applications requiring direct electrical and thermal equivalence to the 74AC540SC, MC74AC540DWG and MC74AC540DWR2G are the primary selections. Both parts maintain identical supply voltage range (2V ~ 6V) and operating temperature range (-40°C ~ 85°C), with the distinction being packaging format: MC74AC540DWG is supplied in Tube packaging, while MC74AC540DWR2G is supplied in Tape & Reel format. Both are active products with ROHS3 compliance.

CD74AC540M96 manufactured by Texas Instruments provides an alternative with extended operating temperature range (-55°C ~ 125°C) and wider supply voltage tolerance (1.5V ~ 5.5V), suitable for applications requiring broader environmental specifications. This part is active and ROHS3 compliant.

CD74AC540M manufactured by Harris Corporation is obsolete and RoHS non-compliant, making it unsuitable for new designs or applications with regulatory compliance requirements.

Frequently Asked Questions (FAQ)

Q: Can MC74AC540DWG directly replace 74AC540SC in existing designs?

A: Yes. Both parts share identical electrical specifications including logic type, bit configuration, output type, drive current, supply voltage range (2V ~ 6V), and operating temperature range (-40°C ~ 85°C). The 20-SOIC package footprint is identical, enabling direct PCB substitution. MC74AC540DWG is an active product, addressing the obsolescence of 74AC540SC.

Q: What is the difference between MC74AC540DWG and MC74AC540DWR2G?

A: Both parts are electrically identical. The difference is packaging format: MC74AC540DWG is supplied in Tube packaging for manual handling and smaller quantities, while MC74AC540DWR2G is supplied in Tape & Reel format for automated assembly processes and higher volume production.

Q: Can CD74AC540M96 be used as a substitute for 74AC540SC?

A: Yes, with design considerations. CD74AC540M96 maintains all core functional parameters (logic type, bit width, output type, drive current, package). However, it operates within a wider supply voltage range (1.5V ~ 5.5V) and extended temperature range (-55°C ~ 125°C). Applications operating within the original 74AC540SC specifications (2V ~ 6V, -40°C ~ 85°C) will function identically. Applications requiring the extended environmental range benefit from CD74AC540M96's broader specifications.

Q: Why is CD74AC540M not recommended as a substitute?

A: CD74AC540M is obsolete and RoHS non-compliant. While electrically functional, it does not meet current regulatory requirements for new designs or production environments with compliance mandates.

Q: Are all substitute parts pin-compatible with 74AC540SC?

A: Yes. All substitute parts use the identical 20-SOIC package with matching pin assignments, enabling direct PCB-level substitution without layout modifications.

Q: What compliance certifications apply to the recommended substitutes?

A: MC74AC540DWG, MC74AC540DWR2G, and CD74AC540M96 are all ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory standards for electronic component manufacturing and distribution.

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