74ACT573SCX D-Type Transparent Latch Equivalent & Substitute Parts

Part Overview

The 74ACT573SCX is a D-Type Transparent Latch IC manufactured by onsemi, featuring 1 channel with 8:8 circuit configuration and tri-state output capability. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The part operates within a 4.5V to 5.5V supply voltage range and is housed in a 20-SOIC surface mount package with a 6ns propagation delay specification.

Key Parameters

Parameter	Value
Manufacturer Part Number	74ACT573SCX
Manufacturer	onsemi
Logic Type	D-Type Transparent Latch
Circuit Configuration	8:8
Output Type	Tri-State
Voltage - Supply	4.5V ~ 5.5V
Delay Time - Propagation	6ns
Current - Output High, Low	24mA, 24mA
Operating Temperature	-40°C ~ 85°C
Package / Case	20-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the 74ACT573SCX is determined by the following critical parameters:

Primary Substitution Criteria:

Logic Type: D-Type Transparent Latch
Circuit Configuration: 8:8
Output Type: Tri-State
Voltage - Supply: 4.5V ~ 5.5V
Package / Case: 20-SOIC (0.295", 7.50mm Width)
Mounting Type: Surface Mount

Secondary Compatibility Factors:

Propagation Delay: 6ns (baseline specification)
Output Current: 24mA minimum for both high and low states
Operating Temperature Range: -40°C minimum to 85°C minimum

Parts are grouped into two categories:

Direct Equivalents (8:8 Circuit Configuration): Parts maintaining identical 8:8 circuit configuration with matching electrical specifications and package dimensions. These provide pin-for-pin compatibility.

Similar Alternatives (1:8 Circuit Configuration): Parts with modified circuit configuration (1:8 instead of 8:8) from the same manufacturer series. These require functional verification but share the same base product family and package footprint.

Alternative Series (74AHCT): Parts from different logic series offering enhanced performance characteristics while maintaining functional compatibility through the same package and pin count.

Parameter Comparison

Part Number	Manufacturer	Circuit	Propagation Delay (ns)	Output Current High/Low (mA)	Operating Temp (°C)	Product Status	Package
74ACT573SCX	onsemi	8:8	6	24/24	-40 ~ 85	Obsolete	20-SOIC
SN74ACT573DWR	Texas Instruments	8:8	6	24/24	-40 ~ 85	Active	20-SOIC
SN74ACT573DW	Texas Instruments	8:8	6	24/24	-40 ~ 85	Discontinued	20-SOIC
SN74ACT573NSR	Texas Instruments	8:8	6	24/24	-40 ~ 85	Active	20-SO
CD74ACT573M	Harris Corporation	8:8	3.1	24/24	-55 ~ 125	Obsolete	20-SOIC
CD74ACT573M96	Harris Corporation	8:8	3.1	24/24	-55 ~ 125	Obsolete	20-SOIC
MC74ACT573DWG	onsemi	1:8	10.5	24/24	-40 ~ 85	Active	20-SOIC
MC74ACT573DWR2G	onsemi	1:8	10.5	24/24	-40 ~ 85	Active	20-SOIC
74AHCT573D,118	Nexperia USA Inc.	8:8	4.6	8/8	-40 ~ 125	Active	20-SOIC

Engineering Selection Recommendations

Recommended Primary Substitute: SN74ACT573DWR

The SN74ACT573DWR from Texas Instruments is the optimal substitute for the obsolete 74ACT573SCX. This part maintains identical electrical specifications (6ns propagation delay, 24mA output current), operates within the same voltage and temperature ranges, and is housed in the same 20-SOIC package. The part is currently in active production status with substantial inventory availability (14,058 units), ensuring long-term procurement reliability. RoHS3 compliance and REACH unaffected status provide regulatory alignment for modern manufacturing environments.

Alternative Direct Equivalent: SN74ACT573DW

The SN74ACT573DW offers identical electrical and package specifications to the primary recommendation. Although discontinued at DiGi Electronics, this part maintains active status with 2,777 units in stock and serves as a viable alternative when primary supply is constrained. Electrical performance is equivalent to the original 74ACT573SCX.

Extended Temperature Range Option: CD74ACT573M or CD74ACT573M96

Both Harris Corporation parts provide superior propagation delay (3.1ns versus 6ns) and extended operating temperature range (-55°C to 125°C versus -40°C to 85°C). These obsolete parts are suitable for applications requiring enhanced thermal performance. Output current specifications remain at 24mA for both high and low states, maintaining compatibility with the original design.

Performance-Enhanced Alternative: 74AHCT573D,118

The Nexperia 74AHCT573 series offers the fastest propagation delay (4.6ns) and widest operating temperature range (-40°C to 125°C) among available substitutes. This part is actively produced and RoHS3 compliant. Note that output current is reduced to 8mA per state, which may require circuit verification in current-limited applications.

Not Recommended for Direct Substitution: MC74ACT573DWG and MC74ACT573DWR2G

These onsemi parts feature a modified 1:8 circuit configuration instead of the original 8:8 configuration. While they share the same package footprint and base product family, the circuit topology difference requires functional validation and may not provide pin-for-pin compatibility depending on application requirements.

Frequently Asked Questions (FAQ)

Q: Can I use SN74ACT573DWR as a direct replacement for 74ACT573SCX?

A: Yes. The SN74ACT573DWR provides pin-for-pin compatibility with identical electrical specifications, package dimensions, and operating parameters. The part is actively manufactured and represents the recommended substitute.

Q: What is the difference between 8:8 and 1:8 circuit configurations?

A: The circuit configuration number indicates the input-to-output relationship. An 8:8 configuration provides eight independent data inputs and eight corresponding outputs. A 1:8 configuration provides one input with eight output paths. These are functionally different and not interchangeable without circuit redesign.

Q: Are the onsemi MC74ACT573 parts suitable replacements?

A: The MC74ACT573DWG and MC74ACT573DWR2G are not recommended as direct substitutes due to their 1:8 circuit configuration. However, they may serve as alternatives if your application can accommodate the modified circuit topology. Functional verification is required.

Q: What does RoHS3 compliance mean for my design?

A: RoHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead and other hazardous materials. This is standard for modern manufacturing and ensures regulatory compliance in most markets.

Q: Can I use the 74AHCT573 series instead of the 74ACT series?

A: The 74AHCT573D,118 is functionally compatible and offers superior performance (faster propagation delay, wider temperature range). However, output current is reduced to 8mA per state compared to 24mA in the original part. Verify that your circuit can operate with reduced drive current before substitution.

Q: What is the significance of MSL (Moisture Sensitivity Level)?

A: MSL indicates moisture sensitivity during storage and handling. MSL 1 (Unlimited) means the part has no moisture sensitivity restrictions and can be stored indefinitely without special precautions. MSL 3 (168 Hours) requires controlled storage conditions and limits shelf life to 168 hours after opening the moisture barrier bag.

Q: Are there supply chain advantages to choosing one substitute over another?

A: SN74ACT573DWR offers the highest inventory availability (14,058 units) and active production status, providing the most reliable long-term supply. Parts marked as obsolete or discontinued may face future availability constraints despite current stock levels.

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