78ST133VC DC DC Converter 3.3V Equivalent & Substitute Parts

Part Overview

The Texas Instruments 78ST133VC is a non-isolated Point-of-Load (PoL) module DC DC converter designed for commercial ITE applications. This component delivers a fixed 3.3V output at 1.5A maximum current from a 7V to 26V input range. The 78ST133VC is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing system support, design updates, and procurement continuity.

Substiute Parts

78ST133VC

Texas InstrumentsIn Stock: 85578ST133VC Datasheet

Current PartRFQ

R-78B3.3-1.5

Recom PowerIn Stock: 12469R-78B3.3-1.5 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 78ST133VC is determined by the following critical parameters:

Output Voltage Compatibility: The substitute part must deliver 3.3V output to maintain circuit functionality.

Output Current Capacity: The substitute must support 1.5A maximum output current to meet load requirements.

Input Voltage Range: The substitute must accept the system input voltage range. The 78ST133VC accepts 7V to 26V input. Substitute parts with narrower input ranges (such as 4.75V to 18V) are functionally compatible when the actual system input voltage falls within both the original and substitute specifications.

Package and Mounting: The substitute must use Through Hole mounting in a 3-SIP Module package to ensure mechanical compatibility with existing PCB layouts.

Operating Temperature: The substitute must support the -40°C to 85°C operating temperature range.

Regulatory Compliance: The substitute must maintain ROHS3 compliance and MSL 1 rating for supply chain and manufacturing compatibility.

The Recom Power R-78B3.3-1.5 meets all critical substitution criteria for applications where the input voltage remains within 4.75V to 18V.

Parameter Comparison

Engineering Selection Recommendations

For Direct Substitution: The Recom Power R-78B3.3-1.5 is the manufacturer-recommended substitute for the obsolete 78ST133VC. Both components deliver identical output voltage (3.3V) and current capacity (1.5A) in the same 3-SIP Module package with Through Hole mounting. Both maintain ROHS3 compliance and MSL 1 rating, ensuring regulatory and supply chain compatibility.

Input Voltage Consideration: The R-78B3.3-1.5 accepts input voltage from 4.75V to 18V, which is narrower than the original 78ST133VC range of 7V to 26V. Substitution is valid only when the actual system input voltage operates within the 4.75V to 18V window. Applications requiring the full 7V to 26V input range of the original part cannot use this substitute without additional input conditioning.

Product Status Advantage: The R-78B3.3-1.5 is classified as Active, ensuring long-term availability, ongoing manufacturing support, and supply chain stability compared to the obsolete 78ST133VC.

Compliance and Certification: Both parts carry identical regulatory certifications (ROHS3, MSL 1, REACH Unaffected, ECCN EAR99, HTSUS 8504.40.9580), eliminating compliance risk in substitution.

Frequently Asked Questions (FAQ)

Q: Can the R-78B3.3-1.5 replace the 78ST133VC in all applications?

A: The R-78B3.3-1.5 is a direct substitute for applications where the system input voltage remains between 4.75V and 18V. If your system requires operation across the full 7V to 26V input range of the original 78ST133VC, the substitute is not suitable without additional input voltage regulation.

Q: Are the physical dimensions compatible?

A: Both components use the 3-SIP Module package with Through Hole mounting. The R-78B3.3-1.5 is physically smaller (11.5mm L x 8.5mm W x 17.5mm H) compared to the 78ST133VC (22.9mm L x 7.9mm W x 23.9mm H). PCB layout verification is required to confirm that the smaller substitute fits within the available space and does not create routing conflicts.

Q: What is the difference between "Non-Isolated PoL Module" and "Linear Regulator Replacement"?

A: Both designations describe functionally equivalent topologies for this application. The 78ST133VC is classified as a Non-Isolated PoL Module, while the R-78B3.3-1.5 is classified as a Linear Regulator Replacement. Both deliver the same output voltage and current with identical thermal and electrical characteristics for ITE commercial applications.

Q: Are there any efficiency differences?

A: The 78ST133VC operates at 80% efficiency, while the R-78B3.3-1.5 operates at 91% efficiency. The substitute provides improved power efficiency, resulting in lower heat dissipation and reduced thermal management requirements.

Q: What is the impact of the narrower input voltage range?

A: The R-78B3.3-1.5 input range (4.75V to 18V) is narrower than the 78ST133VC (7V to 26V). If your system input voltage can exceed 18V, the substitute will not operate. Verify your actual system input voltage specification before selecting this substitute.

Q: Are regulatory certifications identical?

A: Yes. Both the 78ST133VC and R-78B3.3-1.5 carry ROHS3 compliance, MSL 1 rating, REACH Unaffected status, ECCN EAR99 classification, and identical HTSUS code (8504.40.9580). No compliance risk exists in substitution.

Q: Why is the 78ST133VC obsolete?

A: The 78ST133VC is classified as obsolete by Texas Instruments. The Recom Power R-78B3.3-1.5 is the active substitute, ensuring continued availability and manufacturing support for new designs and legacy system maintenance.