78ST133HC DC DC Converter 3.3V Equivalent & Substitute Parts

Part Overview

The Texas Instruments 78ST133HC is a non-isolated Point-of-Load (PoL) module DC DC converter delivering 3.3V output at 1.5A maximum current from a 7V to 26V input range. This component is classified as obsolete, necessitating identification of active equivalent parts for new designs and ongoing production requirements. The 78ST133HC operates across the commercial ITE (Information Technology Equipment) application space with integrated over-temperature protection (OTP) and short-circuit protection (SCP) features.

Substiute Parts

78ST133HC

Texas InstrumentsIn Stock: 91178ST133HC Datasheet

Current PartRFQ

R-78B3.3-1.5L

Recom PowerIn Stock: 12496R-78B3.3-1.5L Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the obsolete 78ST133HC is determined by the following critical electrical and mechanical parameters:

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

Output Current Capacity: The substitute must support a minimum of 1.5A maximum output current.

Input Voltage Range: The substitute input voltage range must encompass or be compatible with the 7V to 26V input specification of the original part. Substitutes with narrower input ranges require circuit-level evaluation.

Package and Mounting: The substitute must utilize a 3-SIP Module package with through-hole, right-angle mounting to ensure mechanical compatibility with existing PCB layouts.

Operating Temperature Range: The substitute must maintain the -40°C to 85°C operating temperature specification.

Protection Features: The substitute must include OTP and SCP protection mechanisms.

Compliance and Status: The substitute must hold active product status and maintain ROHS3 compliance and MSL 1 rating for supply chain continuity.

Parameter Comparison

Engineering Selection Recommendations

The Recom Power R-78B3.3-1.5L serves as the active equivalent substitute for the obsolete Texas Instruments 78ST133HC. Both components deliver identical output voltage (3.3V) and maximum output current (1.5A) specifications with matching operating temperature ranges (-40°C to 85°C) and protection feature sets (OTP, SCP).

Input Voltage Range Consideration: The R-78B3.3-1.5L operates across a 4.75V to 18V input range, which is narrower than the original 78ST133HC specification of 7V to 26V. Applications requiring input voltages below 4.75V or above 18V require circuit-level assessment to determine compatibility.

Efficiency Improvement: The substitute part delivers 91% efficiency compared to the original 80% efficiency rating, resulting in reduced thermal dissipation and improved power conversion performance.

Mechanical and Compliance Alignment: Both components utilize identical 3-SIP Module packaging with through-hole, right-angle mounting, ensuring direct PCB layout compatibility. Both maintain ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity ratings, supporting equivalent supply chain handling and storage requirements.

Product Status: The R-78B3.3-1.5L maintains active product status, ensuring long-term availability and continued manufacturer support, addressing the obsolescence of the original 78ST133HC.

Frequently Asked Questions (FAQ)

Q: Can the R-78B3.3-1.5L directly replace the 78ST133HC in existing designs?

A: Direct replacement is possible when the input voltage range of 4.75V to 18V aligns with the application's power supply specifications. If the original design requires input voltages below 4.75V or above 18V, circuit-level modifications are necessary.

Q: What are the key electrical differences between these parts?

A: Both components deliver 3.3V at 1.5A maximum output current with identical protection features and operating temperature ranges. The primary difference is the input voltage range: the 78ST133HC accepts 7V to 26V, while the R-78B3.3-1.5L accepts 4.75V to 18V. The R-78B3.3-1.5L achieves higher efficiency (91% versus 80%).

Q: Are the physical packages identical?

A: Both components use 3-SIP Module packages with through-hole, right-angle mounting. However, the R-78B3.3-1.5L has different physical dimensions (17.5mm L x 11.5mm W x 8.5mm H) compared to the 78ST133HC (23.9mm L x 22.9mm W x 7.9mm H). PCB layout verification is required to confirm mechanical fit.

Q: Do both parts meet the same compliance standards?

A: Yes. Both the 78ST133HC and R-78B3.3-1.5L are ROHS3 compliant with MSL 1 (Unlimited) ratings, REACH unaffected status, and EAR99 ECCN classification.

Q: What is the primary reason for substitution?

A: The 78ST133HC is classified as obsolete. The R-78B3.3-1.5L is an active product from Recom Power that provides equivalent electrical functionality with improved efficiency and ensures continued supply chain availability.

Q: How should I evaluate compatibility for my specific application?

A: Verify that your application's input voltage range falls within 4.75V to 18V. Confirm that the physical dimensions of the R-78B3.3-1.5L accommodate your PCB layout. Validate that the output current requirement does not exceed 1.5A and that the operating temperature range remains within -40°C to 85°C.