74AC574SC Equivalent & Substitute Parts

Part Overview

The 74AC574SC is a D-Type flip-flop logic integrated circuit manufactured by onsemi, featuring 1 element with 8-bit capacity and tri-state, non-inverted output configuration. This component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing design support and procurement continuity. The 20-SOIC surface mount package remains standard across the 74AC logic family, enabling direct substitution where electrical parameters align.

Key Parameters

Parameter	Value
Part Number	74AC574SC
Manufacturer	onsemi
Type	D-Type Flip-Flop
Number of Elements	1
Number of Bits per Element	8
Output Type	Tri-State, Non-Inverted
Package	20-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
Voltage Supply Range	2V ~ 6V
Operating Temperature	-40°C ~ 85°C
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the 74AC574SC is determined by strict alignment of the following electrical and mechanical parameters:

Critical Matching Parameters:

D-Type flip-flop architecture with 1 element, 8-bit configuration
Tri-state, non-inverted output topology
20-SOIC surface mount package (0.295", 7.50mm Width)
Positive edge trigger mechanism
Supply voltage range compatibility (minimum 2V, maximum 6V)
Operating temperature range overlap (-40°C to 85°C minimum)
Output drive capability (24mA high and low current)

Allowable Variation Parameters:

Clock frequency (153 MHz baseline; substitutes range 95–155 MHz)
Propagation delay (6–10.8ns at 5V, 50pF load)
Quiescent current (4–40 µA)
Input capacitance (4.5–10 pF)
Product status (active substitutes preferred over discontinued)
RoHS and MSL compliance certifications

Substitute parts must maintain functional equivalence in logic operation, pin configuration, and package footprint while meeting or exceeding the original specification in performance-critical parameters.

Parameter Comparison

Parameter	74AC574SC (Main)	MC74AC574DWG	MC74AC574DWR2G	SN74AC374DW	SN74AC574DWR	CD74AC574M96
Manufacturer	onsemi	onsemi	onsemi	Texas Instruments	Texas Instruments	Texas Instruments
Product Status	Obsolete	Active	Active	Discontinued at DiGi Electronics	Active	Active
Type	D-Type	D-Type	D-Type	D-Type	D-Type	D-Type
Number of Elements	1	1	1	1	1	1
Number of Bits per Element	8	8	8	8	8	8
Output Type	Tri-State, Non-Inverted	Tri-State, Non-Inverted	Tri-State, Non-Inverted	Tri-State, Non-Inverted	Tri-State, Non-Inverted	Tri-State, Non-Inverted
Package	20-SOIC	20-SOIC	20-SOIC	20-SOIC	20-SOIC	20-SOIC
Clock Frequency	153 MHz	95 MHz	95 MHz	155 MHz	153 MHz	125 MHz
Max Propagation Delay @ 5V, 50pF	9.5ns	9.5ns	9.5ns	8ns	6ns	10.8ns
Current - Output High, Low	24mA, 24mA	24mA, 24mA	24mA, 24mA	24mA, 24mA	24mA, 24mA	24mA, 24mA
Voltage - Supply	2V ~ 6V	2V ~ 6V	2V ~ 6V	2V ~ 6V	2V ~ 6V	1.5V ~ 5.5V
Current - Quiescent (Iq)	40 µA	8 µA	8 µA	4 µA	4 µA	8 µA
Input Capacitance	4.5 pF	4.5 pF	4.5 pF	4.5 pF	4.5 pF	10 pF
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-55°C ~ 125°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	3 (168 Hours)	3 (168 Hours)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitutes (Active Status, Full Compatibility):

MC74AC574DWG and MC74AC574DWR2G (onsemi) represent direct functional equivalents with active product status. Both maintain identical electrical specifications to the 74AC574SC within the allowed parameter ranges. MC74AC574DWG is supplied in tube packaging, while MC74AC574DWR2G is available in cut tape and digi-reel format. Both comply with ROHS3 standards and carry MSL-3 moisture sensitivity ratings.

SN74AC574DWR (Texas Instruments) is an active substitute offering superior propagation delay performance (6ns versus 9.5ns) and lower quiescent current (4 µA versus 40 µA), with MSL-1 moisture sensitivity and ROHS3 compliance. This part provides enhanced electrical performance within the same package and pin configuration.

Secondary Substitute (Discontinued Status):

SN74AC374DW (Texas Instruments) is discontinued at DiGi Electronics but remains functionally compatible. It exhibits the fastest propagation delay (8ns) and lowest quiescent current (4 µA) among all listed substitutes, with MSL-1 rating and ROHS3 compliance. Procurement availability may be limited.

Extended Temperature Range Alternative:

CD74AC574M96 (Texas Instruments) extends the operating temperature range to -55°C ~ 125°C, suitable for applications requiring wider thermal operation. This part maintains functional equivalence with slightly higher propagation delay (10.8ns) and increased input capacitance (10 pF). ROHS3 compliant with MSL-1 rating.

Frequently Asked Questions (FAQ)

Q: Can the 74AC574SC be directly replaced with any of the listed substitutes?

A: Yes, all listed substitutes maintain identical pin configuration, package footprint (20-SOIC), and core logic function (D-Type flip-flop, 1 element, 8-bit, tri-state non-inverted output). Direct PCB substitution is mechanically and electrically feasible without circuit redesign.

Q: What is the primary reason for substituting the 74AC574SC?

A: The 74AC574SC is classified as obsolete. Active substitutes such as MC74AC574DWG, MC74AC574DWR2G, and SN74AC574DWR ensure long-term procurement availability and supply chain continuity.

Q: Are there performance differences between the main part and substitutes?

A: Yes. Propagation delay ranges from 6ns (SN74AC574DWR) to 10.8ns (CD74AC574M96) compared to 9.5ns for the 74AC574SC. Quiescent current varies from 4 µA to 40 µA. Clock frequency ranges from 95 MHz to 155 MHz. These variations remain within acceptable tolerance for standard logic applications but should be verified for timing-critical designs.

Q: Which substitute offers the best performance?

A: SN74AC574DWR provides the lowest propagation delay (6ns) and quiescent current (4 µA), with active product status and MSL-1 moisture sensitivity. It is suitable for performance-optimized applications.

Q: What is the difference between MC74AC574DWG and MC74AC574DWR2G?

A: Both are onsemi parts with identical electrical specifications. The primary difference is packaging: MC74AC574DWG is supplied in tube format, while MC74AC574DWR2G is available in cut tape and digi-reel format. Selection depends on procurement and assembly requirements.

Q: Does the CD74AC574M96 offer advantages over other substitutes?

A: CD74AC574M96 extends the operating temperature range to -55°C ~ 125°C, compared to -40°C ~ 85°C for other substitutes. This makes it suitable for industrial and military applications requiring wider thermal operation. Trade-offs include slightly higher propagation delay and input capacitance.

Q: Are all substitutes RoHS3 compliant?

A: Yes, all listed substitutes carry ROHS3 compliance certification. The 74AC574SC RoHS status is not specified in the provided data.

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

A: MSL-1 parts (SN74AC374DW, SN74AC574DWR, CD74AC574M96) have unlimited shelf life and require no special moisture control during storage and handling. MSL-3 parts (MC74AC574DWG, MC74AC574DWR2G) require controlled storage conditions with a 168-hour floor life after moisture exposure. Selection depends on supply chain and assembly environment capabilities.

Q: Can the 74AC574SC be used in new designs?

A: No. The 74AC574SC is obsolete and not recommended for new designs. Active substitutes such as MC74AC574DWG, MC74AC574DWR2G, or SN74AC574DWR should be specified for new product development to ensure long-term availability and support.

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