SN54ALS74AJ Equivalent & Substitute Parts

Part Overview

The SN54ALS74AJ is a dual positive-edge-triggered D-type flip flop manufactured by Texas Instruments, designed for logic applications requiring edge-triggered data storage and complementary outputs. This 2-element, 1-bit D-type flip flop operates at a clock frequency of 25 MHz with a maximum propagation delay of 23ns at 5V with 50pF load. The device is housed in a 14-CDIP package and is currently in active production status with 1405 units in stock.

Finding equivalent and substitute parts for the SN54ALS74AJ becomes necessary when addressing supply chain constraints, design optimization requirements, or when transitioning between product generations. The CD74HC74E represents a functionally compatible alternative within the same logic flip flop category.

Substiute Parts

SN54ALS74AJ

Texas InstrumentsIn Stock: 1421SN54ALS74AJ Datasheet

Current PartRFQ

CD74HC74E

Harris CorporationIn Stock: 1470CD74HC74E Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution compatibility for the SN54ALS74AJ is determined by the following critical parameters:

Functional Parameters:

• Type: D-Type flip flop with dual elements (2 elements, 1 bit per element)
• Output configuration: Complementary outputs
• Trigger mechanism: Positive edge-triggered
• Function: Set (Preset) and Reset capability

Electrical Parameters:

• Clock frequency capability (minimum 25 MHz required)
• Propagation delay performance
• Supply voltage range compatibility
• Output current drive capability
• Quiescent current specifications

Physical Parameters:

• Package type: 14-pin DIP configuration (14-CDIP or 14-PDIP)
• Pin pitch: 0.300" (7.62mm)
• Mounting: Through-hole technology

Compliance Parameters:

• RoHS compliance status
• Operating temperature range: -55°C ~ 125°C

The CD74HC74E meets the functional and physical requirements for substitution, maintaining the same dual D-type flip flop architecture, complementary output configuration, positive edge trigger, and 14-pin DIP package footprint. Both devices support the required operating temperature range and through-hole mounting methodology.

Parameter Comparison

Engineering Selection Recommendations

SN54ALS74AJ Selection Criteria:

• Active product status with ongoing manufacturer support
• ROHS3 compliance for applications requiring environmental and regulatory adherence
• Established supply chain with 1405 units currently in stock
• Suitable for new designs and long-term production requirements

CD74HC74E Selection Criteria:

• Obsolete product status limits suitability for new designs
• RoHS non-compliant, restricting use in applications with environmental compliance mandates
• Lower quiescent current (4 µA vs 4 mA) provides power consumption advantage in specific applications
• Higher output current drive (5.2mA vs 2mA/4mA) supports higher fan-out requirements
• Wider supply voltage range (2V ~ 6V) enables operation in broader voltage environments
• Pin-compatible 14-DIP package allows direct board-level substitution where compliance is not a constraint

For new designs and production environments, the SN54ALS74AJ is the recommended primary selection due to active status and RoHS3 compliance. The CD74HC74E may be considered only in legacy system maintenance scenarios where compliance requirements are not applicable and supply constraints necessitate alternative sourcing.

Frequently Asked Questions (FAQ)

Q: Are the SN54ALS74AJ and CD74HC74E pin-compatible?

A: Yes. Both devices use 14-pin DIP packages with 0.300" (7.62mm) pin pitch. The pin configuration for dual D-type flip flops with complementary outputs and Set/Reset functions is identical, enabling direct board-level substitution from a physical standpoint.

Q: What are the key electrical differences between these parts?

A: The CD74HC74E operates at a higher clock frequency (50 MHz vs 25 MHz) and exhibits lower quiescent current (4 µA vs 4 mA). However, the CD74HC74E has slightly higher propagation delay (30ns vs 23ns) and different output current specifications (5.2mA symmetric vs 2mA/4mA asymmetric). The CD74HC74E also supports a wider supply voltage range (2V ~ 6V vs 4.5V ~ 5.5V).

Q: Can I use the CD74HC74E as a direct replacement in a new design?

A: Direct substitution is not recommended for new designs. The CD74HC74E is obsolete and RoHS non-compliant, making it unsuitable for applications requiring regulatory compliance or long-term supply assurance. The SN54ALS74AJ is the appropriate choice for new product development.

Q: What is the significance of the different RoHS compliance status?

A: The SN54ALS74AJ is ROHS3 compliant, meeting current environmental and hazardous substance restrictions. The CD74HC74E is RoHS non-compliant, restricting its use in applications subject to environmental regulations, EU directives, or customer-mandated compliance requirements. This is a critical consideration for commercial and industrial applications.

Q: How do the quiescent current specifications affect component selection?

A: The CD74HC74E draws significantly lower quiescent current (4 µA) compared to the SN54ALS74AJ (4 mA). In battery-powered or low-power applications where standby current is critical, the CD74HC74E offers a substantial power consumption advantage. However, this benefit must be weighed against its obsolete status and compliance limitations.

Q: Are there any performance considerations for high-speed applications?

A: The CD74HC74E supports higher clock frequency (50 MHz vs 25 MHz) and may be suitable for applications requiring faster operation. However, the CD74HC74E exhibits slightly higher propagation delay (30ns vs 23ns), which may impact timing-critical designs. The SN54ALS74AJ remains the preferred choice for applications operating at or near 25 MHz with strict timing requirements.

Q: What should I consider regarding output current drive capability?

A: The CD74HC74E provides symmetric output current (5.2mA high and low) compared to the SN54ALS74AJ (2mA high, 4mA low). Applications requiring higher fan-out or driving multiple logic inputs may benefit from the CD74HC74E's increased drive capability. The SN54ALS74AJ is adequate for standard logic-level loads within its specified output current ratings.