SPD125-394M Fixed Inductor - Equivalent & Substitute Parts

Part Overview

The SPD125-394M is a 390 µH shielded surface mount inductor manufactured by API Delevan Inc., rated for 650 mA continuous current with a maximum DC resistance of 750 mOhm. This component is classified as obsolete, necessitating the identification of functionally equivalent alternatives for ongoing design and production applications. Equivalent parts must match or exceed the critical performance parameters while meeting modern compliance standards.

Substiute Parts

SPD125-394M

API Delevan Inc.In Stock: 1082SPD125-394M Datasheet

Current PartRFQ

SRR1206-391KL

Bourns Inc.In Stock: 695SRR1206-391KL Datasheet

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Key Parameters

Substitute Part Grouping Explanation

The SRR1206-391KL from Bourns Inc. qualifies as an equivalent substitute for the SPD125-394M based on the following critical parameters:

Matching Parameters:

• Inductance Value: Both parts are 390 µH ±10% to ±20%
• Shielded Construction: Both employ ferrite core shielding
• Surface Mount Technology: Both utilize surface mount packaging
• Operating Temperature Range: The SRR1206-391KL range (-40°C to 125°C) encompasses the SPD125-394M operating window
• Moisture Sensitivity: Both rated at MSL 1 (Unlimited)
• Core Material: Both utilize ferrite core construction

Performance Trade-offs: The SRR1206-391KL exhibits a lower maximum current rating (550 mA vs. 650 mA) but provides higher saturation current (950 mA vs. 650 mA). The DC resistance is higher at 870 mOhm maximum compared to 750 mOhm, with an improved inductance tolerance of ±10%.

Parameter Comparison

Engineering Selection Recommendations

The SRR1206-391KL serves as the primary equivalent for the obsolete SPD125-394M. Key decision factors include:

Compliance Advantage: The SRR1206-391KL carries RoHS3 compliance, whereas the SPD125-394M is non-compliant. This is critical for new designs and production environments subject to regulatory requirements.

Product Availability: The SRR1206-391KL maintains active product status with current manufacturing, ensuring supply continuity. The SPD125-394M obsolescence status eliminates long-term sourcing viability.

Current Rating Trade-off: The substitution reduces the continuous current rating from 650 mA to 550 mA. Circuit designs operating below 550 mA continuous current are directly compatible. Designs requiring the full 650 mA rating require validation for the reduced margin.

DC Resistance Impact: The increased DC resistance (870 mOhm vs. 750 mOhm) results in approximately 16% higher I²R losses. Thermal analysis of the specific application determines acceptability.

Physical Footprint: The SRR1206-391KL footprint is marginally larger (12.70mm x 12.70mm vs. 12.00mm x 12.00mm) with a 0.5mm additional height. PCB layout space validation is required before substitution.

Frequently Asked Questions (FAQ)

Q: Can the SRR1206-391KL directly replace the SPD125-394M in all applications?

A: Direct replacement is permissible for applications operating at continuous currents below 550 mA. Applications utilizing the full 650 mA rating require circuit redesign validation. The increased DC resistance and thermal characteristics must be evaluated for specific thermal environments.

Q: What is the impact of the ±10% tolerance specification for the SRR1206-391KL versus the ±20% tolerance of the SPD125-394M?

A: The tighter ±10% tolerance of the SRR1206-391KL provides greater inductance consistency, reducing design margin requirements and improving filter or impedance-matching circuit performance. This is a performance benefit for circuits sensitive to inductance variation.

Q: Are there PCB layout compatibility concerns between these parts?

A: The SRR1206-391KL requires slightly more board space (12.70mm x 12.70mm footprint, 6.50mm height) compared to the SPD125-394M (12.00mm x 12.00mm, 6.00mm height). Verify footprint clearance, solder pad configuration, and component height constraints before PCB redesign confirmation.

Q: How does the higher saturation current of the SRR1206-391KL affect compatibility?

A: The higher saturation current (950 mA) of the SRR1206-391KL provides improved linearity under transient current conditions. This parameter does not restrict substitution but indicates improved performance in applications experiencing current surges below 950 mA.

Q: What compliance advantages does the SRR1206-391KL offer?

A: The SRR1206-391KL is RoHS3 compliant and carries active product status, meeting modern regulatory requirements and ensuring manufacturing continuity. The SPD125-394M non-compliance status excludes it from applications with RoHS mandates.