PM40-271K Equivalent & Substitute Parts

Part Overview

The PM40-271K is a 270 µH unshielded molded inductor manufactured by Bourns Inc., rated for 92 mA with a maximum DC resistance of 18Ω in a 1812 (4532 Metric) surface mount package. This part is classified as obsolete, making equivalent substitutes necessary for ongoing production and design requirements. Substitute parts must maintain the same inductance value, current rating, package dimensions, and mounting type to ensure direct compatibility in existing circuit designs.

Substiute Parts

PM40-271K

Bourns Inc.In Stock: 717PM40-271K Datasheet

Current PartRFQ

CM453232-271JL

Bourns Inc.In Stock: 3185CM453232-271JL Datasheet

DirectRFQ

CM453232-271KL

Bourns Inc.In Stock: 2370CM453232-271KL Datasheet

DirectRFQ

CM453232-R33ML

Bourns Inc.In Stock: 1925CM453232-R33ML Datasheet

DirectRFQ

1812-274J

API Delevan Inc.In Stock: 9581812-274J Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the PM40-271K is determined by the following critical parameters:

Primary Compatibility Criteria:

• Inductance value: 270 µH (exact match required)
• Current rating: minimum 92 mA
• Package / Case: 1812 (4532 Metric)
• Mounting type: Surface Mount
• Core material: Ferrite
• Shielding: Unshielded

Secondary Compatibility Criteria:

• DC resistance: lower or equal to 18Ω is acceptable
• Operating temperature range: must support -55°C to 125°C or equivalent
• Inductance tolerance: ±10% or tighter acceptable

Parts are grouped into two categories:

Direct Substitutes (Bourns CM45 Series): CM453232-271JL and CM453232-271KL maintain identical inductance (270 µH), current rating (92 mA), and package specifications. Both feature improved DC resistance (12Ω max) and active product status.

Similar Substitute (API Delevan 1812 Series): 1812-274J provides 270 µH inductance with higher current rating (129 mA) and equivalent DC resistance (12Ω max), maintaining full package and mounting compatibility.

Non-Compatible Part: CM453232-R33ML has significantly different inductance (330 nH) and current rating (605 mA), making it unsuitable for direct substitution despite identical package dimensions.

Parameter Comparison

Engineering Selection Recommendations

Preferred Substitutes:

CM453232-271JL and CM453232-271KL are the primary recommended substitutes. Both are manufactured by Bourns Inc. (original manufacturer), maintain active product status, and achieve ROHS3 compliance. These parts provide superior DC resistance (12Ω vs. 18Ω), higher Q factor (40 vs. 30), and improved self-resonant frequency (4MHz vs. 3MHz). The inductance tolerance difference (±5% vs. ±10%) offers tighter specification control. The reduced operating temperature minimum (-40°C vs. -55°C) is acceptable for most applications unless extended low-temperature operation is required.

Alternative Substitute:

1812-274J from API Delevan Inc. provides full electrical and mechanical compatibility with the advantage of higher current rating (129 mA vs. 92 mA), offering additional design margin. This part maintains the full operating temperature range (-55°C ~ 125°C) matching the original specification. However, it retains RoHS non-compliant status, which may conflict with regulatory requirements in new designs.

Non-Recommended:

CM453232-R33ML must not be used as a substitute due to fundamentally different electrical specifications (330 nH inductance and 605 mA current rating), despite identical package dimensions.

Frequently Asked Questions (FAQ)

Q: Can CM453232-271JL directly replace PM40-271K in existing designs?

A: Yes. Both parts share identical inductance (270 µH), current rating (92 mA), and 1812 package dimensions. The lower DC resistance (12Ω vs. 18Ω) and higher Q factor represent performance improvements. The reduced minimum operating temperature (-40°C vs. -55°C) must be evaluated against application requirements.

Q: What is the difference between CM453232-271JL and CM453232-271KL?

A: Both parts are electrically and mechanically identical with one exception: inductance tolerance. CM453232-271JL specifies ±5% tolerance, while CM453232-271KL specifies ±10% tolerance. Selection depends on circuit tolerance requirements. Both are Bourns CM45 series drum core wirewound inductors with active status and ROHS3 compliance.

Q: Is 1812-274J suitable for applications requiring -55°C operation?

A: Yes. The 1812-274J maintains the full operating temperature range (-55°C ~ 125°C) of the original PM40-271K. It is suitable for extended low-temperature applications. However, verify RoHS compliance requirements, as this part is RoHS non-compliant.

Q: Why is CM453232-R33ML listed in the original part's substitutes but not recommended here?

A: CM453232-R33ML has fundamentally different electrical specifications (330 nH vs. 270 µH inductance and 605 mA vs. 92 mA current rating). Despite sharing the 1812 package, it is not electrically compatible and cannot function as a direct substitute in circuits designed for 270 µH inductance.

Q: What are the package dimension implications for substitution?

A: All recommended substitutes maintain identical external dimensions (0.177" L x 0.126" W / 4.50mm x 3.20mm) and the 1812 (4532 Metric) package specification. Height differences (CM45 series at 0.134" vs. PM40 at 0.126") are within typical PCB assembly tolerances and do not affect mounting compatibility.

Q: Does lower DC resistance in substitute parts affect circuit behavior?

A: Lower DC resistance (12Ω vs. 18Ω) reduces power dissipation and heat generation in the inductor. For most applications, this represents an improvement. However, circuits with precise impedance matching or specific loss requirements should evaluate the impact on overall circuit performance.