74HCT640N,652 Equivalent & Substitute Parts

Part Overview

The 74HCT640N,652 is an inverting transceiver logic integrated circuit manufactured by NXP USA Inc. in a 20-DIP package. This component functions as a 1-element, 8-bit transceiver with 3-state output capability, designed for digital signal inversion and buffering applications in TTL-compatible systems. The part is classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing system maintenance and new designs requiring compatible logic performance.

Substiute Parts

74HCT640N,652

NXP USA Inc.In Stock: 121674HCT640N,652 Datasheet

Current PartRFQ

CD74HCT540E

Harris CorporationIn Stock: 1747CD74HCT540E Datasheet

DirectRFQ

CD74HCT640E

Harris CorporationIn Stock: 1610CD74HCT640E Datasheet

UpgradeRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 74HCT640N,652 is determined by the following critical parameters:

Core Functional Parameters:

• Logic type classification (Transceiver, Inverting or Buffer, Inverting)
• Number of elements: 1
• Number of bits per element: 8
• Output configuration: 3-State
• Output current capability: 6mA, 6mA (High, Low)

Electrical Compatibility Parameters:

• Supply voltage range: 4.5V ~ 5.5V
• Package form factor: 20-DIP (0.300", 7.62mm)
• Mounting type: Through Hole

Compliance Parameters:

• ECCN classification: EAR99
• HTSUS code: 8542.39.0001

The identified substitute parts maintain compatibility across these core parameters while operating within the same electrical envelope and physical footprint.

Parameter Comparison

Engineering Selection Recommendations

CD74HCT640E (Upgrade Option): The CD74HCT640E from Harris Corporation provides direct functional equivalence to the 74HCT640N,652. Both components are classified as inverting transceivers with identical electrical specifications and package form factors. The CD74HCT640E extends the operating temperature range to -55°C ~ 125°C, providing enhanced performance in lower-temperature environments. However, the CD74HCT640E is RoHS non-compliant, whereas the main part maintains ROHS3 compliance. This substitution is appropriate for applications where RoHS compliance is not a regulatory requirement.

CD74HCT540E (Direct Substitution with Functional Difference): The CD74HCT540E is classified as a buffer rather than a transceiver, representing a functional variant within the same electrical and physical specifications. This part maintains identical output current, supply voltage, and package characteristics. The extended operating temperature range (-55°C ~ 125°C) provides additional thermal margin. Selection of this part requires confirmation that buffer functionality is compatible with the circuit application, as the transceiver-to-buffer transition may affect bidirectional signal handling requirements.

Both substitute parts share the same ECCN (EAR99) and HTSUS (8542.39.0001) classifications as the main part, ensuring consistent regulatory treatment.

Frequently Asked Questions (FAQ)

Q: Can the CD74HCT540E replace the 74HCT640N,652 in all applications?

A: The CD74HCT540E maintains electrical and physical compatibility but differs in logic type classification. The main part is a transceiver (bidirectional signal handling), while the CD74HCT540E is a buffer (unidirectional). Substitution is valid only if the circuit application requires buffer functionality rather than transceiver functionality.

Q: What is the difference between the CD74HCT540E and CD74HCT640E?

A: Both parts are manufactured by Harris Corporation and share identical electrical specifications and package form factors. The primary distinction is logic type: CD74HCT540E is a buffer, while CD74HCT640E is a transceiver. The CD74HCT640E provides direct functional equivalence to the 74HCT640N,652.

Q: Are there RoHS-compliant alternatives available?

A: The main part (74HCT640N,652) is ROHS3 compliant. The identified substitute parts (CD74HCT540E and CD74HCT640E) are RoHS non-compliant. If RoHS compliance is a design requirement, alternative sourcing or design modification may be necessary.

Q: Do the substitute parts fit the same PCB footprint?

A: Yes. All parts use the 20-DIP (0.300", 7.62mm) package form factor with through-hole mounting. Direct PCB footprint compatibility is confirmed.

Q: What is the temperature operating range difference?

A: The 74HCT640N,652 operates from -40°C to 125°C. Both substitute parts extend the lower temperature limit to -55°C, providing an additional 15°C of cold-temperature margin. The upper temperature limit remains 125°C across all three parts.