PM40-R18M Equivalent & Substitute Parts

Part Overview

The PM40-R18M is a 180 nH unshielded molded inductor manufactured by Bourns Inc., rated for 450 mA with a maximum DC resistance of 280 mOhm in a 1812 (4532 Metric) surface mount package. This part is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design support and procurement continuity. Substitute parts must maintain electrical compatibility across inductance, current rating, DC resistance, and mechanical form factor while meeting modern compliance requirements.

Substiute Parts

PM40-R18M

Bourns Inc.In Stock: 810PM40-R18M Datasheet

Current PartRFQ

CM453232-R18KL

Bourns Inc.In Stock: 1063CM453232-R18KL Datasheet

DirectRFQ

CM453232-R18ML

Bourns Inc.In Stock: 737CM453232-R18ML Datasheet

DirectRFQ

1812-181K

API Delevan Inc.In Stock: 6761812-181K Datasheet

SimilarRFQ

IMC1812BNR18M

Vishay DaleIn Stock: 999IMC1812BNR18M Datasheet

SimilarRFQ

IMC1812EBR18M

Vishay DaleIn Stock: 982IMC1812EBR18M Datasheet

SimilarRFQ

IMC1812ERR18M

Vishay DaleIn Stock: 1084IMC1812ERR18M Datasheet

SimilarRFQ

IMC1812ESR18M

Vishay DaleIn Stock: 1073IMC1812ESR18M Datasheet

SimilarRFQ

IMC1812RQR18M

Vishay DaleIn Stock: 885IMC1812RQR18M Datasheet

SimilarRFQ

IMC1812RVR18M

Vishay DaleIn Stock: 1002IMC1812RVR18M Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

• Inductance Value: Must be 180 nH
• Package / Case: Must be 1812 (4532 Metric) surface mount
• Current Rating: Must support minimum 450 mA
• DC Resistance: Must not exceed 280 mOhm maximum
• Shielding: Must be unshielded
• Operating Temperature Range: Must encompass -55°C to 125°C or equivalent
• Frequency Characteristics: Q factor and self-resonant frequency should align with application requirements

Substitute parts are categorized as direct equivalents (matching all electrical and mechanical parameters) or similar alternatives (meeting core electrical requirements with acceptable parameter variations).

Parameter Comparison

Engineering Selection Recommendations

Direct Equivalents (Bourns CM45 Series)

CM453232-R18KL and CM453232-R18ML are active production alternatives from Bourns Inc. Both maintain 180 nH inductance in the 1812 package with improved current ratings (700 mA) and lower DC resistance (240 mOhm). CM453232-R18ML matches the ±20% tolerance of the original part. Both are ROHS3 compliant, addressing regulatory requirements absent in the obsolete PM40-R18M.

Compatible Alternatives (Vishay Dale IMC-1812 Series)

IMC1812EBR18M, IMC1812ERR18M, and IMC1812ESR18M provide active production equivalents with matching 180 nH inductance, ±20% tolerance, and 450 mA current rating. These parts feature non-magnetic cores identical to the original and are ROHS3 compliant. DC resistance is specified at 350 mOhm maximum, exceeding the original 280 mOhm specification. IMC1812BNR18M offers identical electrical parameters but is supplied in bulk packaging rather than tape and reel.

Secondary Alternative (API Delevan 1812-181K)

The 1812-181K maintains 180 nH inductance and 1812 package form factor with higher current rating (757 mA) but exhibits elevated DC resistance (350 mOhm) and iron core construction. This part remains RoHS non-compliant and is suitable only where compliance requirements are not mandated.

Frequently Asked Questions (FAQ)

Q: Can CM453232-R18KL or CM453232-R18ML directly replace PM40-R18M?

A: Yes. Both parts maintain 180 nH inductance in the 1812 surface mount package with superior electrical performance (lower DCR, higher current rating) and active production status. The ferrite core construction differs from the original non-magnetic core but does not preclude substitution in standard RF and filtering applications. ROHS3 compliance addresses regulatory gaps in the obsolete part.

Q: What is the impact of increased DC resistance in Vishay Dale alternatives?

A: Vishay Dale IMC-1812 series parts specify 350 mOhm maximum DCR compared to 280 mOhm in the original. This 25% increase affects power dissipation and thermal performance. Selection depends on circuit current levels and thermal budget. For 450 mA operation, the additional dissipation is approximately 22.5 mW at maximum DCR, requiring thermal analysis in power-sensitive applications.

Q: Are packaging differences between tape and reel and bulk significant?

A: Packaging format (tape and reel vs. bulk) affects procurement and assembly processes but not electrical or mechanical compatibility. Tape and reel packaging (IMC1812ERR18M, IMC1812ESR18M) is standard for automated assembly. Bulk packaging (IMC1812BNR18M) requires manual handling and is suitable for lower-volume or prototype applications.

Q: Why do some alternatives have higher current ratings than the original?

A: Higher current ratings reflect improved inductor design and materials. CM453232 series parts (700 mA) and the 1812-181K (757 mA) provide design margin and thermal headroom. These ratings do not mandate higher operating currents; circuits designed for 450 mA operation remain fully compatible.

Q: What compliance considerations apply to substitute selection?

A: The original PM40-R18M is RoHS non-compliant. Bourns CM45 series and Vishay Dale IMC-1812 variants with ROHS3 designation (CM453232-R18KL, CM453232-R18ML, IMC1812EBR18M, IMC1812ERR18M, IMC1812ESR18M) satisfy modern regulatory requirements. Selection of compliant alternatives is mandatory for applications subject to RoHS directives.

Q: How do core material differences affect circuit performance?

A: The original PM40-R18M uses non-magnetic core construction. Bourns CM45 series employs ferrite cores, offering improved Q factor (35 @ 25.2 MHz vs. 30 @ 25.2 MHz) and lower self-resonant frequency (220 MHz vs. 400 MHz). Vishay Dale IMC-1812 alternatives retain non-magnetic cores, maintaining frequency characteristics identical to the original. Core selection depends on application frequency range and Q requirements.