PM40-1R8K Equivalent & Substitute Parts

Part Overview

The PM40-1R8K is a 1.8 µH unshielded molded inductor manufactured by Bourns Inc., rated for 390 mA with a maximum DC resistance of 650mOhm in a 1812 (4532 Metric) surface mount package. This component operates across a temperature range of -55°C to 125°C and is currently classified as obsolete. Due to its obsolete status, equivalent and substitute parts from active product lines are necessary for ongoing design support and procurement continuity.

Substiute Parts

PM40-1R8K

Bourns Inc.In Stock: 655PM40-1R8K Datasheet

Current PartRFQ

CM453232-1R8JL

Bourns Inc.In Stock: 1258CM453232-1R8JL Datasheet

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CM453232-1R8KL

Bourns Inc.In Stock: 1720CM453232-1R8KL Datasheet

DirectRFQ

CM453232-R15ML

Bourns Inc.In Stock: 2817CM453232-R15ML Datasheet

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1812-182J

API Delevan Inc.In Stock: 8591812-182J Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the PM40-1R8K are classified based on electrical and mechanical compatibility within the following criteria:

Direct Substitutes (Bourns CM45 Series): Parts CM453232-1R8JL and CM453232-1R8KL maintain identical inductance (1.8 µH), current rating (390 mA), DC resistance (650mOhm Max), package dimensions (1812), and frequency characteristics (Q @ 7.96MHz, 60MHz self-resonant frequency). These parts differ in core material (ferrite drum core versus iron powder molded) and tolerance specifications, but operate within the same electrical performance envelope.

Similar Substitute (API Delevan 1812-182J): This part matches the 1.8 µH inductance, 390 mA current rating, 650mOhm DC resistance, and 1812 package footprint. It provides functional equivalence with slightly higher current capability (556 mA) and maintains the same frequency characteristics.

Non-Equivalent Part (CM453232-R15ML): This part is listed for reference only and is not a functional substitute due to significantly different inductance (150 nH versus 1.8 µH) and current rating (730 mA versus 390 mA).

Parameter Comparison

Engineering Selection Recommendations

Preferred Substitutes: CM453232-1R8JL and CM453232-1R8KL are the primary recommended alternatives. Both parts are active products from Bourns Inc. with ROHS3 compliance, ensuring long-term availability and regulatory alignment. CM453232-1R8KL matches the ±10% tolerance of the original part, while CM453232-1R8JL offers tighter ±5% tolerance. Both maintain identical electrical performance across all critical parameters. The minor height difference (0.134" versus 0.126") must be verified against PCB layout constraints.

Secondary Substitute: 1812-182J from API Delevan Inc. provides functional equivalence with active product status. This part offers higher current capability (556 mA) and ±5% tolerance. However, it does not meet ROHS3 compliance and has a narrower operating temperature range (-55°C to 125°C matches the original, but the lower bound is -55°C). Selection of this part requires confirmation that RoHS non-compliance is acceptable for the application.

Temperature Consideration: If the application requires operation below -40°C, only PM40-1R8K or 1812-182J support the full -55°C lower limit. The Bourns CM45 series substitutes operate only to -40°C minimum.

Frequently Asked Questions (FAQ)

Q: Can CM453232-1R8JL and CM453232-1R8KL be used interchangeably with PM40-1R8K?

A: Yes, both parts are direct electrical and mechanical substitutes. They maintain identical inductance (1.8 µH), current rating (390 mA), DC resistance (650mOhm Max), and package footprint (1812). The primary differences are core material composition (ferrite drum core versus iron powder molded) and tolerance specification (±5% versus ±10%). Both are active products with ROHS3 compliance.

Q: What is the impact of the height difference between PM40-1R8K and the CM45 series substitutes?

A: PM40-1R8K has a seated height of 0.126" (3.20mm), while CM453232-1R8JL and CM453232-1R8KL have a seated height of 0.134" (3.40mm). This 0.008" (0.20mm) difference must be evaluated against PCB layout, solder mask clearances, and component placement constraints. Verify clearance with adjacent components and thermal management requirements.

Q: Is 1812-182J a suitable replacement if ROHS3 compliance is not required?

A: 1812-182J provides functional equivalence with identical inductance, DC resistance, and package dimensions. It offers higher current capability (556 mA versus 390 mA) and ±5% tolerance. However, it does not meet ROHS3 compliance. Selection depends on regulatory requirements for the end application. Confirm that RoHS non-compliance is acceptable before implementation.

Q: Why is CM453232-R15ML listed but not recommended as a substitute?

A: CM453232-R15ML has significantly different electrical specifications: 150 nH inductance (versus 1.8 µH) and 730 mA current rating (versus 390 mA). These differences make it unsuitable for applications designed for the PM40-1R8K. This part is included for reference only to prevent accidental selection.

Q: What are the key parameters that determine substitution compatibility?

A: Substitution compatibility is determined by: inductance value (1.8 µH), current rating (390 mA minimum), DC resistance (650mOhm maximum), package footprint (1812 / 4532 Metric), mounting type (surface mount), and frequency characteristics (Q @ 7.96MHz, 60MHz self-resonant frequency). All substitute parts must match these parameters within the specified tolerances.