78SR105SC DC DC Converter 5V Equivalent & Substitute Parts

Part Overview

The Texas Instruments 78SR105SC is a non-isolated point-of-load (PoL) module DC DC converter delivering 5V output at 1.5A maximum current from a 7V to 30V input range. This surface mount device is classified as obsolete product status, necessitating identification of active equivalent and substitute components for ongoing design support and procurement continuity. The 78SR105SC operates across the commercial ITE (Information Technology Equipment) application space with integrated over-temperature protection (OTP) and short-circuit protection (SCP) features.

Substiute Parts

78SR105SC

Texas InstrumentsIn Stock: 107278SR105SC Datasheet

Current PartRFQ

R-78B5.0-1.5L

Recom PowerIn Stock: 64916R-78B5.0-1.5L Datasheet

MFR RecommendedRFQ

R-78T5.0-1.0/FC-TRAY

Recom PowerIn Stock: 828R-78T5.0-1.0/FC-TRAY Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the obsolete 78SR105SC requires evaluation against the following critical parameters that define functional equivalence:

Output Specification Alignment: All substitute parts must deliver 5V output voltage with minimum 1.5A current capacity to maintain load compatibility.

Input Voltage Compatibility: The 78SR105SC accepts 7V to 30V input. Substitute parts must support this input range or a range that encompasses the primary operating window of the original design.

Topology and Mounting: The original device is a non-isolated PoL module in surface mount configuration. Substitutes may include alternative topologies (linear regulator replacement) and mounting methods (through-hole) provided electrical performance meets or exceeds the original specification.

Protection and Compliance: All substitute parts must include equivalent protection features (OTP, SCP) and maintain ROHS3 and REACH compliance status.

Operating Temperature: Substitute parts must support the full -40°C to 85°C operating range.

Two active substitute parts are identified:

1. R-78T5.0-1.0/FC-TRAY (Recom Power): Non-isolated PoL module topology match with extended input voltage range (8V to 42V) and surface mount packaging. Output current is reduced to 1A.

2. R-78B5.0-1.5L (Recom Power): Linear regulator replacement topology with matching 1.5A output current capacity. Input range is narrower (6.5V to 18V) and mounting is through-hole configuration.

Parameter Comparison

Engineering Selection Recommendations

For Direct Topology Replacement (Surface Mount Non-Isolated PoL):

The R-78T5.0-1.0/FC-TRAY maintains the non-isolated PoL module topology and surface mount configuration of the original 78SR105SC. This substitute is suitable for applications where the output current requirement can be reduced from 1.5A to 1A, or where load current does not exceed 1A. The extended input voltage range (8V to 42V) provides broader input compatibility. The R-78T5.0-1.0/FC-TRAY achieves 92% efficiency, exceeding the original 85% specification. All compliance certifications (ROHS3, REACH) are maintained. This part is currently active in production with established inventory availability.

For Current-Matched Replacement (1.5A Output Capacity):

The R-78B5.0-1.5L preserves the 1.5A maximum output current of the original device, ensuring full load capacity compatibility. This substitute employs a linear regulator replacement topology and through-hole mounting configuration, requiring PCB layout modification from the original surface mount design. The input voltage range (6.5V to 18V) is narrower than the original specification but covers the primary 7V to 30V window from 6.5V to 18V. The R-78B5.0-1.5L achieves 94% efficiency and includes both OTP and SCP protection features. All compliance certifications are maintained. This part is currently active with high inventory availability (64,845 units in stock).

Selection Criteria:

Choose R-78T5.0-1.0/FC-TRAY when: PCB layout accommodates surface mount configuration, output current requirement is 1A or less, and extended input voltage range (up to 42V) is beneficial.

Choose R-78B5.0-1.5L when: Full 1.5A output current capacity is required, PCB layout can accommodate through-hole right-angle mounting, and input voltage remains within 6.5V to 18V range.

Frequently Asked Questions (FAQ)

Q: Can the R-78T5.0-1.0/FC-TRAY directly replace the 78SR105SC in existing designs?

A: The R-78T5.0-1.0/FC-TRAY provides functional substitution for applications requiring 1A or less output current. Both devices are non-isolated PoL modules in surface mount configuration with identical 5V output voltage and matching operating temperature range. The package dimensions are similar (25.0 x 23.0 x 10.0mm versus 23.9 x 22.9 x 8.6mm), permitting PCB layout compatibility in most cases. Applications requiring the full 1.5A output current of the original device require the R-78B5.0-1.5L instead.

Q: What is the impact of the narrower input voltage range on the R-78B5.0-1.5L?

A: The R-78B5.0-1.5L input range of 6.5V to 18V encompasses the primary operating window of the original 78SR105SC (7V to 30V) from 6.5V to 18V. Applications with input voltages exceeding 18V require the R-78T5.0-1.0/FC-TRAY (8V to 42V range) or alternative solutions. Verify the actual input voltage distribution in your application before selecting this substitute.

Q: Does the through-hole mounting of the R-78B5.0-1.5L require PCB redesign?

A: Yes. The original 78SR105SC is surface mount (3-SMD Module), while the R-78B5.0-1.5L is through-hole right-angle configuration (3-SIP Module). PCB layout modification is required, including hole placement and trace routing adjustments. The R-78T5.0-1.0/FC-TRAY maintains surface mount compatibility and may require only minor footprint adjustments.

Q: Are protection features equivalent between the original and substitute parts?

A: The 78SR105SC includes OTP and SCP protection. The R-78T5.0-1.0/FC-TRAY includes SCP only (OTP not listed). The R-78B5.0-1.5L includes both OTP and SCP, matching the original specification. Applications requiring over-temperature protection should use the R-78B5.0-1.5L or verify that the R-78T5.0-1.0/FC-TRAY thermal management is adequate for the operating environment.

Q: What is the efficiency improvement of the substitute parts?

A: The original 78SR105SC operates at 85% efficiency. The R-78T5.0-1.0/FC-TRAY achieves 92% efficiency (7 percentage point improvement), and the R-78B5.0-1.5L achieves 94% efficiency (9 percentage point improvement). Higher efficiency reduces thermal dissipation and power loss, benefiting overall system performance and thermal management.

Q: Are both substitute parts currently available?

A: Yes. The R-78T5.0-1.0/FC-TRAY is active with 771 units in stock. The R-78B5.0-1.5L is active with 64,845 units in stock, providing significantly higher availability for immediate procurement.

Q: Do the substitute parts maintain regulatory compliance?

A: Both substitute parts are ROHS3 compliant and REACH unaffected, matching the compliance status of the original 78SR105SC. Both are classified under HTSUS code 8504.40.9580 and ECCN EAR99, consistent with the original device.