PM42S-121 Equivalent & Substitute Parts

Part Overview

The PM42S-121 is a 120 µH shielded drum core, wirewound inductor manufactured by Bourns Inc., rated for 180 mA maximum current with a DC resistance of 2.39Ohm. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing design support and procurement continuity. The part operates across a temperature range of -30°C to 100°C and is mounted as a surface mount device in a nonstandard package measuring 4.80mm x 4.80mm.

Substiute Parts

PM42S-121

Bourns Inc.In Stock: 1152PM42S-121 Datasheet

Current PartRFQ

SRR4018-121Y

Bourns Inc.In Stock: 753SRR4018-121Y Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the PM42S-121 is based on the following critical parameters:

• Inductance Value: 120 µH (±30% tolerance maintained)
• Core Type & Shielding: Ferrite drum core with shielding required
• Mounting Configuration: Surface mount, identical footprint (4.80mm x 4.80mm)
• Current Handling: Minimum 180 mA rating required
• DC Resistance: Lower DCR values are acceptable as they indicate improved performance
• Physical Dimensions: Height must not exceed 2.00mm seated height

The SRR4018-121Y meets all substitution criteria with enhanced electrical performance characteristics and active product status.

Parameter Comparison

Engineering Selection Recommendations

The SRR4018-121Y is the direct substitute for the obsolete PM42S-121. Selection is justified on the following basis:

Product Status: The PM42S-121 is obsolete, while the SRR4018-121Y maintains active product status, ensuring long-term availability and supply chain continuity.

Electrical Compatibility: Both components share identical inductance values (120 µH) and tolerance specifications (±30%). The SRR4018-121Y provides superior current handling capacity (330 mA versus 180 mA), with lower DC resistance (1.95Ohm versus 2.39Ohm), resulting in reduced power dissipation and improved thermal performance.

Regulatory Compliance: The SRR4018-121Y is ROHS3 compliant, addressing modern regulatory requirements. The PM42S-121 is non-compliant, making the substitute necessary for applications subject to RoHS directives.

Physical Compatibility: Identical footprint and maximum seated height ensure direct mechanical substitution without PCB redesign.

Temperature Performance: The SRR4018-121Y extends the operating temperature range to -40°C to 125°C, providing broader environmental coverage compared to the PM42S-121 range of -30°C to 100°C.

Frequently Asked Questions (FAQ)

Q: Can the SRR4018-121Y directly replace the PM42S-121 without circuit modifications?

A: Yes. Both components maintain identical inductance values, tolerance specifications, and physical footprints. The SRR4018-121Y provides enhanced current rating and lower DC resistance, making it functionally superior for the same application space.

Q: What are the key differences between these two inductors?

A: The primary differences are product status (obsolete versus active), current rating (180 mA versus 330 mA), DC resistance (2.39Ohm versus 1.95Ohm), operating temperature range (-30°C to 100°C versus -40°C to 125°C), and regulatory compliance (non-compliant versus ROHS3 compliant).

Q: Is the packaging difference significant?

A: The PM42S-121 uses nonstandard packaging, while the SRR4018-121Y is supplied in standard Tape & Reel (TR) format. This improves handling, storage, and automated assembly compatibility for the substitute part.

Q: Will the lower DC resistance of the SRR4018-121Y affect circuit performance?

A: Lower DC resistance reduces power dissipation and heat generation, which is beneficial for circuit efficiency. No negative effects are introduced by this parameter improvement.

Q: Are both parts from the same manufacturer?

A: Yes, both the PM42S-121 and SRR4018-121Y are manufactured by Bourns Inc., ensuring consistent design philosophy and quality standards.