SC3DF-120 Equivalent & Substitute Parts

Part Overview

The SC3DF-120 is a 12 µH unshielded wirewound inductor manufactured by Signal Transformer, rated for 1 A continuous current with a maximum DC resistance of 350 mOhm. This component is classified as obsolete, making equivalent substitutes necessary for new designs and production continuity. The part operates across the industrial temperature range of -40°C to 125°C and is ROHS3 compliant.

Substiute Parts

SC3DF-120

Signal TransformerIn Stock: 1181SC3DF-120 Datasheet

Current PartRFQ

SDR0703-120KL

Bourns Inc.In Stock: 2328SDR0703-120KL Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SC3DF-120 is based on the following critical parameters:

• Inductance Value: 12 µH (primary electrical requirement)
• Current Rating: Minimum 1 A continuous current capability
• DC Resistance: Lower or equivalent to 350 mOhm to maintain circuit performance
• Saturation Current: Minimum 590 mA to prevent core saturation under load
• Mounting Type: Surface Mount (SMD) form factor compatibility
• Operating Temperature Range: -40°C ~ 125°C minimum
• Shielding Configuration: Unshielded topology
• Compliance: ROHS3 and REACH compliance required

The SDR0703-120KL from Bourns Inc. meets these substitution criteria with equivalent inductance, compatible current ratings, superior DC resistance characteristics, and matching environmental specifications.

Parameter Comparison

Engineering Selection Recommendations

The SDR0703-120KL is the qualified substitute for the SC3DF-120 based on the following engineering criteria:

Electrical Compatibility: Both components provide 12 µH inductance at 100 kHz test frequency. The SDR0703-120KL offers tighter inductance tolerance (±10% versus ±20%), reducing circuit variability. The substitute's superior saturation current (1.3 A versus 590 mA) and lower DC resistance (180 mOhm versus 350 mOhm) provide improved performance margins.

Current Rating Consideration: The SDR0703-120KL is rated for 900 mA continuous current, which is 100 mA below the original 1 A specification. This difference requires circuit-level evaluation for applications operating at or near the 1 A threshold.

Compliance and Availability: The SDR0703-120KL maintains ROHS3 and REACH compliance matching the original part. As an active product from Bourns Inc., it provides long-term supply continuity and availability advantages over the obsolete SC3DF-120.

Physical Form Factor: Both components share identical surface mount packaging with compatible footprints (6.50mm L × 4.40mm W for SC3DF-120; 6.50mm L × 4.50mm W for SDR0703-120KL), enabling direct PCB layout compatibility with minimal design modification.

Frequently Asked Questions (FAQ)

Q: Can the SDR0703-120KL directly replace the SC3DF-120 in all applications?

A: Direct substitution is valid for circuits where the continuous current requirement does not exceed 900 mA. Applications requiring the full 1 A rating must undergo circuit analysis to confirm adequate performance margins with the substitute part's 900 mA specification.

Q: What is the impact of the lower DC resistance in the SDR0703-120KL?

A: The SDR0703-120KL's 180 mOhm maximum DC resistance is superior to the SC3DF-120's 350 mOhm specification. This reduction decreases resistive losses and heat generation, improving overall circuit efficiency. No negative impact occurs from this parameter difference.

Q: Are the physical dimensions compatible for PCB layout?

A: Yes. The SC3DF-120 measures 6.50mm L × 4.40mm W × 3.10mm H (seated), while the SDR0703-120KL measures 6.50mm L × 4.50mm W × 2.70mm H (seated). The length is identical, width differs by 0.10mm, and the substitute is 0.40mm shorter. These minor dimensional variations are within typical PCB design tolerances for surface mount components.

Q: Does the inductance tolerance difference affect circuit performance?

A: The SDR0703-120KL provides ±10% tolerance versus the SC3DF-120's ±20% tolerance. This tighter tolerance reduces inductance variation across production batches, improving circuit consistency and reducing design margin requirements.

Q: What is the difference between wirewound and drum core construction?

A: The SC3DF-120 uses standard wirewound construction, while the SDR0703-120KL uses drum core wirewound construction with ferrite material. Both are unshielded topologies. The drum core design contributes to the SDR0703-120KL's improved saturation current and lower DC resistance characteristics.

Q: Are both parts available in the same packaging format?

A: The SC3DF-120 is supplied in standard packaging, while the SDR0703-120KL is available in Tape & Reel (TR) format. Both are surface mount components compatible with automated assembly processes.