PM125S-331M Equivalent & Substitute Parts

Part Overview

The PM125S-331M is a 330 µH shielded drum core wirewound inductor manufactured by Bourns Inc., rated for 570 mA continuous current with a maximum DC resistance of 800mOhm. This surface mount component features ferrite core construction with nonstandard packaging and operates across the temperature range of -40°C to 125°C. The part is currently classified as obsolete, making identification of suitable alternatives essential for ongoing design support and procurement continuity.

Substiute Parts

PM125S-331M

Bourns Inc.In Stock: 1073PM125S-331M Datasheet

Current PartRFQ

SRR1205-331KL

Bourns Inc.In Stock: 752SRR1205-331KL Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

The SRR1205-331KL qualifies as a substitute for the PM125S-331M based on the following critical parameters:

Matching Parameters:

• Inductance value: 330 µH (identical)
• Core material: Ferrite (identical)
• Shielding: Shielded (identical)
• Mounting type: Surface mount (identical)
• Operating temperature range: -40°C to 125°C (identical)
• Package classification: Nonstandard (identical)

Allowable Variations:

• Current rating: 540 mA (SRR1205-331KL) versus 570 mA (PM125S-331M) — within acceptable tolerance for applications not requiring maximum current capacity
• DC resistance: 1.34Ohm Max (SRR1205-331KL) versus 800mOhm Max (PM125S-331M) — represents a measurable increase in resistive losses
• Saturation current: 880mA (SRR1205-331KL) versus 780mA (PM125S-331M) — provides improved headroom
• Tolerance: ±10% (SRR1205-331KL) versus ±20% (PM125S-331M) — tighter tolerance specification

Parameter Comparison

Engineering Selection Recommendations

The SRR1205-331KL is the designated substitute for the obsolete PM125S-331M. Selection of this alternative is supported by the following factors:

Product Status: The SRR1205-331KL maintains active production status with Bourns Inc., ensuring long-term availability and supply chain stability compared to the obsolete PM125S-331M.

Regulatory Compliance: The SRR1205-331KL achieves ROHS3 compliance, whereas the PM125S-331M is non-compliant. This distinction is significant for applications subject to RoHS directives and environmental regulations.

Electrical Performance: Both inductors share identical inductance values and core materials. The SRR1205-331KL exhibits a tighter inductance tolerance (±10% versus ±20%), which may improve circuit performance in applications sensitive to inductance variation. The increased DC resistance of the SRR1205-331KL (1.34Ohm versus 800mOhm) represents the primary trade-off and must be evaluated against thermal and efficiency requirements in the target application.

Current Handling: The PM125S-331M supports 570 mA continuous current, while the SRR1205-331KL is rated for 540 mA. Applications operating below 540 mA experience no limitation. Designs requiring the full 570 mA capacity must be reassessed for thermal and performance impact.

Frequently Asked Questions (FAQ)

Q: Can the SRR1205-331KL directly replace the PM125S-331M in existing designs?

A: Direct substitution is possible for applications operating at or below 540 mA continuous current. The increased DC resistance (1.34Ohm versus 800mOhm) will increase resistive losses and heat generation. Thermal analysis of the target application is necessary to confirm acceptability.

Q: What is the significance of the inductance tolerance difference?

A: The PM125S-331M carries ±20% tolerance, while the SRR1205-331KL carries ±10% tolerance. The tighter tolerance of the substitute part may improve circuit performance in applications where inductance variation directly affects circuit behavior, such as resonant or filtering circuits.

Q: Are there package dimension differences between these parts?

A: Both parts are classified as nonstandard package types. The PM125S-331M measures 0.496" L x 0.457" W x 0.213" H (12.60mm x 11.60mm x 5.40mm seated height). The SRR1205-331KL measures 0.500" L x 0.500" W x 0.217" H (12.70mm x 12.70mm x 5.50mm seated height). These dimensional differences are minimal and typically accommodate standard PCB footprints designed for either part.

Q: How does the self-resonant frequency difference affect substitution?

A: The PM125S-331M exhibits a self-resonant frequency of 4 MHz, while the SRR1205-331KL is rated at 2 MHz. Applications operating near or above 2 MHz must account for this reduced self-resonant frequency in the substitute part, as it may affect high-frequency performance characteristics.

Q: What compliance certifications apply to each part?

A: The PM125S-331M is RoHS non-compliant. The SRR1205-331KL is ROHS3 compliant. Both parts are REACH unaffected and classified under ECCN EAR99 and HTSUS 8504.50.4000. For applications subject to RoHS requirements, the SRR1205-331KL is the only compliant option.