DM74AS645N Equivalent & Substitute Parts

Part Overview

The DM74AS645N is a non-inverting transceiver IC manufactured by onsemi, designed for 8-bit data transmission with a single element configuration. This component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing system support and new designs. The part is housed in a 20-PDIP package suitable for through-hole mounting applications.

Substiute Parts

DM74AS645N

onsemiIn Stock: 693DM74AS645N Datasheet

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SN74AS645N

Texas InstrumentsIn Stock: 2134SN74AS645N Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the DM74AS645N is determined by the following critical parameters:

• Logic Function: Non-inverting transceiver architecture with 1 element and 8 bits per element
• Package Compatibility: 20-DIP (0.300", 7.62mm) form factor for through-hole mounting
• Series Compatibility: 74AS logic family designation
• Base Product Number: 74AS645 platform

The SN74AS645N from Texas Instruments satisfies all substitution criteria. Both parts share identical logic configuration, package specifications, and base product platform. The SN74AS645N maintains active product status with enhanced specifications including defined output characteristics (3-State output, 15mA/64mA output current) and operating temperature range (0°C ~ 70°C).

Parameter Comparison

Engineering Selection Recommendations

The SN74AS645N is the direct functional equivalent for DM74AS645N replacement. Selection of the Texas Instruments part provides the following advantages:

• Active Product Status: Ensures long-term availability and manufacturing support
• RoHS3 Compliance: Meets current environmental and regulatory requirements, whereas the original part is non-compliant
• Documented Specifications: Complete electrical parameters (output current, supply voltage, operating temperature) are defined, enabling precise circuit validation
• Package Compatibility: Identical 20-DIP through-hole package allows direct socket substitution without PCB redesign

For applications requiring the DM74AS645N, the SN74AS645N substitution is valid based on matching logic architecture, package form factor, and series designation.

Frequently Asked Questions (FAQ)

Q: Can the SN74AS645N directly replace the DM74AS645N in existing designs?

A: Yes. Both parts share identical logic configuration (non-inverting transceiver, 1 element, 8 bits per element), package specification (20-DIP), and mounting type (through-hole). Direct socket substitution is possible without circuit modification.

Q: What is the significance of the 3-State output specification in the SN74AS645N?

A: The 3-State output capability is a functional characteristic of the 74AS645 transceiver architecture. This specification is documented for the SN74AS645N but not explicitly stated for the DM74AS645N. Both parts implement the same logic function.

Q: Why is RoHS compliance important for this substitution?

A: The DM74AS645N is RoHS non-compliant, while the SN74AS645N is ROHS3 compliant. For new designs or systems subject to environmental regulations, the compliant part is required. For legacy system maintenance, compliance requirements depend on application jurisdiction and customer specifications.

Q: Are there any package or pinout differences between these parts?

A: No. Both parts use the 20-DIP (0.300", 7.62mm) package with identical through-hole mounting specifications. Pinout compatibility is maintained.

Q: What should be verified when implementing the SN74AS645N as a substitute?

A: Confirm that the application circuit operates within the documented supply voltage range (4.5V ~ 5.5V) and operating temperature range (0°C ~ 70°C) of the SN74AS645N. Verify that output current requirements (15mA high, 64mA low) are compatible with the circuit design.