DM74LS243N Equivalent & Substitute Parts

Part Overview

The DM74LS243N is a Logic Transceiver, Non-Inverting component manufactured by onsemi in a 14-DIP package. This device functions as a 1 Element, 4 Bit per Element transceiver with 3-State output capability, designed for digital signal routing and buffering applications. The part is classified as Obsolete, making identification of compatible substitutes essential for ongoing system support and component procurement.

Substiute Parts

DM74LS243N

onsemiIn Stock: 1627DM74LS243N Datasheet

Current PartRFQ

SN74LS243N

Texas InstrumentsIn Stock: 2355SN74LS243N Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the DM74LS243N is determined by the following critical parameters:

• Logic Family & Function: 74LS series, Transceiver, Non-Inverting topology
• Electrical Specifications: Voltage supply 4.75V ~ 5.25V, output current 15mA (high) and 24mA (low)
• Pin Configuration: 1 Element, 4 Bits per Element architecture
• Physical Package: 14-DIP form factor with 0.300" (7.62mm) pitch for Through Hole mounting
• Output Characteristics: 3-State or Push-Pull output capability

The SN74LS243N from Texas Instruments meets all functional and electrical requirements. While the output type differs (Push-Pull vs. 3-State), both configurations operate within identical voltage and current parameters, making this substitution electrically compatible for applications where output stage characteristics are functionally equivalent.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS243N from Texas Instruments is the primary substitute for the obsolete DM74LS243N. Selection is justified on the following basis:

• Functional Equivalence: Both parts implement identical 74LS transceiver architecture with matching pin counts, voltage specifications, and current ratings.
• Package Compatibility: Identical 14-DIP Through Hole package ensures direct PCB footprint compatibility without layout modification.
• Active Product Status: The SN74LS243N maintains Active status with established supply chains, ensuring long-term availability compared to the Obsolete DM74LS243N.
• Regulatory Compliance: The SN74LS243N carries ROHS3 Compliant certification, meeting modern environmental and regulatory requirements.
• Output Stage Consideration: The transition from 3-State to Push-Pull output requires circuit-level evaluation. Push-Pull output provides continuous drive capability, whereas 3-State allows high-impedance bus sharing. Application requirements determine suitability.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS243N directly replace the DM74LS243N without circuit modification?

A: Pin-for-pin replacement is possible due to identical package and pinout. However, the output type difference (Push-Pull vs. 3-State) requires verification that the receiving circuit can accommodate continuous drive rather than high-impedance state capability.

Q: What is the primary difference between these two parts?

A: The output stage configuration differs. The DM74LS243N provides 3-State output (active high, active low, high-impedance), while the SN74LS243N provides Push-Pull output (active high, active low only). Both maintain identical voltage and current specifications.

Q: Are the electrical specifications identical?

A: Yes. Both parts operate at 4.75V ~ 5.25V supply voltage with 15mA output high current and 24mA output low current. Operating temperature range is 0°C ~ 70°C for both devices.

Q: Why is the DM74LS243N listed as Obsolete?

A: Obsolete status indicates the manufacturer (onsemi) has discontinued production. The SN74LS243N from Texas Instruments remains in active production, providing continuity for new designs and system maintenance.

Q: Does package compatibility guarantee functional compatibility?

A: Package compatibility ensures physical and electrical interface compatibility. Functional compatibility requires verification that output stage characteristics (Push-Pull vs. 3-State) meet application requirements.

Q: What compliance certifications apply to the substitute part?

A: The SN74LS243N carries ROHS3 Compliant certification. Both parts are REACH Unaffected and classified under ECCN EAR99 and HTSUS 8542.39.0001.