74HCT138DB,118 Equivalent & Substitute Parts

Part Overview

The 74HCT138DB,118 is a decoder/demultiplexer logic integrated circuit manufactured by Nexperia USA Inc. in a 16-SSOP surface mount package. This device implements a 1 x 3:8 decoder function with single supply operation, designed for digital logic applications requiring address decoding and signal demultiplexing.

The 74HCT138DB,118 carries an Obsolete product status. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or maintenance requirements for systems utilizing this component.

Substiute Parts

74HCT138DB,118

Nexperia USA Inc.In Stock: 95474HCT138DB,118 Datasheet

Current PartRFQ

74HCT138PW,118

NXP SemiconductorsIn Stock: 386251474HCT138PW,118 Datasheet

SimilarRFQ

SN74HCT138PWR

Texas InstrumentsIn Stock: 93341SN74HCT138PWR Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 74HCT138DB,118 is determined by the following critical parameters:

Functional Equivalence: All substitute parts must implement the identical 1 x 3:8 decoder/demultiplexer configuration with matching output current specifications (4mA high, 4mA low).

Electrical Compatibility: Supply voltage range (4.5V ~ 5.5V) and logic family (74HCT) must be maintained to ensure direct functional replacement without circuit redesign.

Thermal Operating Range: The original part operates from -40°C to 125°C. Substitute parts operating within this range or a subset thereof are electrically compatible, though thermal envelope differences must be noted for system-level thermal design considerations.

Package Compatibility: The 16-SSOP package footprint (0.209", 5.30mm width) defines the mechanical interface. Substitute parts in alternative 16-pin packages (such as 16-TSSOP with 0.173", 4.40mm width) require PCB layout modification and are not pin-for-pin compatible at the board level.

Compliance and Certification: RoHS3 compliance and MSL rating (1 - Unlimited) are maintained across all identified substitutes, ensuring regulatory and environmental compatibility.

Parameter Comparison

Engineering Selection Recommendations

74HCT138PW,118 (NXP Semiconductors): This part is functionally equivalent with identical electrical parameters and operating temperature range (-40°C ~ 125°C). Active product status ensures ongoing availability. The primary consideration is package transition from 16-SSOP to 16-TSSOP, requiring PCB layout modification. RoHS compliance status is not explicitly specified in available data.

SN74HCT138PWR (Texas Instruments): This part maintains functional equivalence and active product status with ROHS3 compliance certification. The operating temperature range is reduced to -40°C ~ 85°C, which may limit suitability for applications requiring the full -40°C ~ 125°C envelope. Package transition from 16-SSOP to 16-TSSOP requires PCB layout modification.

For applications where the original -40°C ~ 125°C operating range is mandatory, 74HCT138PW,118 is the preferred substitute. For applications operating within -40°C ~ 85°C, both substitutes are viable, with SN74HCT138PWR offering explicit ROHS3 compliance documentation.

Frequently Asked Questions (FAQ)

Q: Can 74HCT138PW,118 or SN74HCT138PWR be used as direct pin-for-pin replacements for 74HCT138DB,118?

A: No. While functionally equivalent, the package types differ. The original uses 16-SSOP (0.209", 5.30mm width), while both substitutes use 16-TSSOP (0.173", 4.40mm width). PCB layout and footprint modification is required.

Q: What is the functional difference between these decoder/demultiplexer parts?

A: All three parts implement identical 1 x 3:8 decoder logic with matching output current specifications (4mA high, 4mA low) and supply voltage requirements (4.5V ~ 5.5V). Functional behavior is equivalent.

Q: Does operating temperature range affect substitution eligibility?

A: The original part operates -40°C ~ 125°C. The 74HCT138PW,118 matches this range. The SN74HCT138PWR operates -40°C ~ 85°C. For applications requiring the full temperature envelope, 74HCT138PW,118 is the appropriate choice.

Q: Are all three parts RoHS compliant?

A: The 74HCT138DB,118 and SN74HCT138PWR are explicitly ROHS3 compliant. The 74HCT138PW,118 RoHS status is not specified in available documentation.

Q: What is the moisture sensitivity level for these parts?

A: All three parts carry MSL rating 1 (Unlimited), indicating no moisture sensitivity restrictions for storage or handling.