74ACTQ74SC Equivalent & Substitute Parts

Part Overview

The 74ACTQ74SC is a dual D-type flip-flop logic integrated circuit manufactured by onsemi, housed in a 14-SOIC package. This component functions as a 2-element D-type flip-flop with complementary outputs, set/preset and reset capabilities, and positive edge triggering. The part is currently obsolete, making equivalent substitute parts necessary for ongoing design support and production continuity. Substitute parts must maintain functional equivalence across core electrical parameters including supply voltage, output drive capability, propagation delay, and package compatibility.

Substiute Parts

74ACTQ74SC

onsemiIn Stock: 396974ACTQ74SC Datasheet

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MC74ACT74DG

onsemiIn Stock: 2049MC74ACT74DG Datasheet

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MC74ACT74DR2G

onsemiIn Stock: 6226MC74ACT74DR2G Datasheet

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CD74ACT74M96

Texas InstrumentsIn Stock: 1786CD74ACT74M96 Datasheet

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CD74ACT74QM96G4Q1

Texas InstrumentsIn Stock: 3300CD74ACT74QM96G4Q1 Datasheet

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SN74ACT74D

Texas InstrumentsIn Stock: 3013SN74ACT74D Datasheet

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SN74ACT74DR

Texas InstrumentsIn Stock: 2228SN74ACT74DR Datasheet

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SN74ACT74MDREP

Texas InstrumentsIn Stock: 2064SN74ACT74MDREP Datasheet

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SN74ACT74NSR

Texas InstrumentsIn Stock: 3874SN74ACT74NSR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 74ACTQ74SC is determined by the following core parameters:

• Functional Equivalence: All substitutes must be dual D-type flip-flops with complementary outputs, set/preset and reset functions, and positive edge triggering.
• Electrical Compatibility: Supply voltage range (4.5V – 5.5V), output drive current (24 mA minimum), and propagation delay performance must be maintained or improved.
• Package Compatibility: All substitutes must use 14-SOIC surface mount packaging. Variants with different body widths (0.154" vs. 0.209") are mechanically compatible but require PCB layout verification.
• Thermal Performance: Operating temperature range must support the application's requirements; extended temperature variants (-55°C to +125°C) are acceptable for designs requiring broader thermal margins.

Substitute parts are grouped into two categories:

Active Status Parts (Recommended for new designs): MC74ACT74DG, MC74ACT74DR2G, SN74ACT74DR, SN74ACT74MDREP, SN74ACT74NSR, CD74ACT74M96

Obsolete/Discontinued Parts (Limited availability): CD74ACT74QM96G4Q1, SN74ACT74D

Parameter Comparison

Engineering Selection Recommendations

For Standard Operating Conditions (-40°C to +85°C):

MC74ACT74DG and MC74ACT74DR2G are direct functional replacements with active product status and ROHS3 compliance. Both maintain the 4.5V – 5.5V supply range and 24 mA output drive capability. Propagation delay increases from 8 ns to 11 ns, which is acceptable for most 74ACT logic applications operating at or below 200 MHz. Quiescent current is significantly reduced (4 µA vs. 20 µA), providing power efficiency benefits.

SN74ACT74DR offers superior propagation delay performance (7.5 ns) with lower quiescent current (2 µA) and active product status. This part is suitable for timing-critical applications where the original 8 ns specification is marginal.

For Extended Temperature Applications (-55°C to +125°C):

SN74ACT74MDREP provides active status with extended thermal range and maintains 210 MHz clock frequency capability. Propagation delay is 11 ns with 2 µA quiescent current.

CD74ACT74M96 is an active alternative with extended temperature range, though clock frequency is reduced to 85 MHz. This part is suitable only for applications not requiring the full 200 MHz performance envelope.

Packaging Considerations:

SN74ACT74NSR uses a wider 14-SOIC package (0.209" vs. 0.154"). While electrically equivalent, PCB layout and footprint compatibility must be verified before substitution.

Compliance Status:

All active substitute parts carry ROHS3 compliance. The original 74ACTQ74SC does not specify RoHS status. Designs requiring RoHS certification should prioritize active-status substitutes.

Frequently Asked Questions (FAQ)

Q: Can MC74ACT74DG directly replace 74ACTQ74SC in existing designs?

A: Yes. Both parts share identical supply voltage (4.5V – 5.5V), output drive current (24 mA), operating temperature range (-40°C to +85°C), and 14-SOIC package. Propagation delay increases from 8 ns to 11 ns, which remains within acceptable limits for standard 74ACT logic timing budgets. No circuit modifications are required.

Q: What is the impact of increased propagation delay (11 ns vs. 8 ns)?

A: The 3 ns increase affects setup and hold time margins in synchronous circuits. For applications operating at or below 200 MHz with standard timing margins, this change is transparent. High-speed designs operating near maximum clock frequency should evaluate timing impact using circuit simulation or static timing analysis.

Q: Are onsemi and Texas Instruments substitutes interchangeable?

A: Yes, provided electrical parameters remain within specification. Both manufacturers produce 74ACT74 logic devices with identical functional behavior, supply voltage, and output drive capability. Quiescent current and propagation delay vary slightly between manufacturers, but all active-status parts meet the core electrical requirements.

Q: Can SN74ACT74NSR (0.209" package) be used in place of 74ACTQ74SC (0.154" package)?

A: Electrically, yes. Mechanically, the wider package requires PCB footprint verification. If the original design uses a 0.154" footprint, the 0.209" variant will not fit without layout modification. Consult PCB design files and component placement constraints before substitution.

Q: Which substitute offers the best performance?

A: SN74ACT74DR provides the fastest propagation delay (7.5 ns) and lowest quiescent current (2 µA) with active product status. For timing-critical applications, this part is the optimal choice. For general-purpose replacement with power efficiency, MC74ACT74DG or MC74ACT74DR2G are suitable.

Q: Are extended temperature variants (-55°C to +125°C) backward compatible?

A: Yes. Extended temperature parts operate correctly within the original -40°C to +85°C range. They are suitable for designs requiring broader thermal margins or operation in harsh environments. No electrical or functional differences exist within the standard temperature range.

Q: What is the significance of ROHS3 compliance?

A: ROHS3 compliance indicates the part meets European Union Restriction of Hazardous Substances regulations. All active-status substitutes carry this certification. If your design or supply chain requires RoHS compliance, select only active-status parts.