PM40-R27M Equivalent & Substitute Parts

Part Overview

The PM40-R27M is a 270 nH unshielded molded inductor manufactured by Bourns Inc., rated for 450 mA with a maximum DC resistance of 360 mOhm in a 1812 (4532 Metric) surface mount package. This part is classified as obsolete, making identification of equivalent and substitute components essential for ongoing design support and production continuity. Substitute parts must maintain the same inductance value, package footprint, and operating temperature range while meeting or exceeding electrical performance specifications.

Substiute Parts

PM40-R27M

Bourns Inc.In Stock: 1189PM40-R27M Datasheet

Current PartRFQ

CM453232-R27KL

Bourns Inc.In Stock: 773CM453232-R27KL Datasheet

DirectRFQ

CM453232-R27ML

Bourns Inc.In Stock: 749CM453232-R27ML Datasheet

DirectRFQ

1812-271K

API Delevan Inc.In Stock: 7401812-271K Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the PM40-R27M are qualified based on the following criteria:

Primary Matching Parameters:

• Inductance value: 270 nH (exact match required)
• Package footprint: 1812 (4532 Metric) surface mount (exact match required)
• Shielding type: Unshielded (exact match required)
• Inductance tolerance: ±20% or tighter
• Current rating: Equal to or greater than 450 mA
• DC resistance: Equal to or less than 360 mOhm
• Operating temperature range: Must encompass -55°C to 125°C or equivalent

Substitute Categories:

Direct Substitutes (Bourns CM45 Series): CM453232-R27KL and CM453232-R27ML maintain identical inductance, package, and shielding specifications. Both feature improved current ratings (635 mA) and lower DC resistance (260 mOhm), with active product status and RoHS3 compliance.

Similar Substitute (API Delevan 1812 Series): The 1812-271K provides equivalent inductance and package specifications with a higher current rating (668 mA). DC resistance matches the original specification at 450 mOhm maximum. This part maintains the original operating temperature range and remains in active production.

Parameter Comparison

Engineering Selection Recommendations

CM453232-R27KL and CM453232-R27ML (Bourns): These direct substitutes are preferred for new designs and production transitions. Both parts are in active production status with ROHS3 compliance certification. The CM453232-R27KL offers ±10% inductance tolerance compared to the original ±20%, providing tighter specification control. Both variants deliver superior electrical performance with 635 mA current rating and 260 mOhm DC resistance. The primary consideration is the reduced lower operating temperature limit (-40°C versus -55°C); applications requiring operation below -40°C must retain the original PM40-R27M or evaluate the 1812-271K alternative.

1812-271K (API Delevan): This substitute maintains the full -55°C to 125°C operating temperature range and provides higher current capacity (668 mA). The DC resistance specification (450 mOhm maximum) exceeds the original part by 90 mOhm. This part remains in active production but does not carry RoHS3 compliance. Selection of this part is appropriate for applications requiring the extended low-temperature operating range or where regulatory compliance is not a constraint.

Frequently Asked Questions (FAQ)

Q: Can CM453232-R27KL and CM453232-R27ML be used interchangeably?

A: Yes. Both parts are electrically and mechanically identical with the exception of inductance tolerance (±10% for -R27KL, ±20% for -R27ML). Selection between these variants depends on tolerance requirements for the specific application circuit.

Q: What is the impact of the reduced lower operating temperature limit in the Bourns CM45 series?

A: The CM453232 series operates from -40°C to 125°C, compared to the PM40-R27M range of -55°C to 125°C. Applications requiring operation below -40°C must use the original PM40-R27M or the 1812-271K alternative. Verify circuit operating conditions before substitution.

Q: Are there mechanical compatibility concerns with the 1812 package substitutes?

A: No. All substitute parts use the identical 1812 (4532 Metric) surface mount package with matching footprint dimensions (0.177" L x 0.126" W / 4.50mm x 3.20mm). Height variations are minimal (0.126" to 0.134" seated height) and do not affect PCB assembly or clearance requirements.

Q: How do the DC resistance differences affect circuit performance?

A: The Bourns CM45 series offers lower DC resistance (260 mOhm) compared to the original 360 mOhm specification, reducing resistive losses and heat generation. The 1812-271K maintains 450 mOhm maximum DC resistance, which exceeds the original specification. For applications sensitive to resistive losses, the CM45 series provides improved efficiency.

Q: What is the significance of the Q factor differences?

A: The Bourns CM45 series exhibits higher Q values (40 @ 25.2 MHz) compared to both the original part and the 1812-271K (30 @ 25.2 MHz). Higher Q indicates lower losses at the test frequency. The self-resonant frequency differs between substitutes (180 MHz for CM45 versus 300-320 MHz for others), which may affect performance in high-frequency applications above 150 MHz.

Q: Are RoHS compliance certifications required for this substitution?

A: RoHS compliance requirements depend on application and regulatory jurisdiction. The Bourns CM45 series carries ROHS3 certification, while the original PM40-R27M and API Delevan 1812-271K do not. Verify compliance requirements before final part selection.