PM40-121K Equivalent & Substitute Parts

Part Overview

The PM40-121K is a 120 µH unshielded molded inductor manufactured by Bourns Inc., rated for 110 mA with a maximum DC resistance of 8Ohm. This component operates across a temperature range of -55°C to 125°C in a 1812 (4532 Metric) surface mount package. The part is classified as obsolete, making identification of suitable alternatives necessary for ongoing design support and production continuity.

Substiute Parts

PM40-121K

Bourns Inc.In Stock: 1074PM40-121K Datasheet

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CM453232-121JL

Bourns Inc.In Stock: 2932CM453232-121JL Datasheet

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CM453232-121KL

Bourns Inc.In Stock: 1160CM453232-121KL Datasheet

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CM453232-680KL

Bourns Inc.In Stock: 14183CM453232-680KL Datasheet

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1812-124J

API Delevan Inc.In Stock: 9651812-124J Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the PM40-121K are classified based on electrical parameter compatibility within the 1812 surface mount package. The primary substitution criteria are:

Direct Electrical Equivalents (120 µH, 110 mA rated):

• CM453232-121JL and CM453232-121KL maintain identical inductance (120 µH) and current rating (110 mA) with matching DC resistance (8Ohm Max) and package dimensions
• These parts differ in core material (ferrite drum core vs. iron powder molded) and tolerance specifications (±5% and ±10% respectively)
• Both are active products with improved RoHS3 compliance status

Partial Electrical Equivalent (68 µH, 130 mA rated):

• CM453232-680KL operates at a different inductance value (68 µH) with higher current rating (130 mA) and lower DC resistance (6Ohm Max)
• This part is suitable only where circuit design permits inductance variation and benefits from increased current capacity

Similar Manufacturer Alternative (120 µH, 158 mA rated):

• 1812-124J from API Delevan Inc. matches the 120 µH inductance and 8Ohm DC resistance with enhanced current rating (158 mA)
• Manufactured by a different supplier using ferrite core material
• Maintains identical package and temperature range specifications

Parameter Comparison

Engineering Selection Recommendations

For direct replacement with improved compliance: CM453232-121KL is the primary substitute, offering identical electrical specifications (120 µH, 110 mA, 8Ohm) with ROHS3 compliance and active product status. The ±10% tolerance matches the original PM40-121K specification. Operating temperature range is reduced to -40°C ~ 125°C; applications requiring -55°C minimum operation require alternative selection.

For enhanced performance with compliance: CM453232-121JL provides tighter tolerance (±5%) and ROHS3 compliance with identical core electrical parameters. The reduced operating temperature minimum (-40°C) applies the same constraint as CM453232-121KL.

For applications permitting inductance variation: CM453232-680KL operates at 68 µH with increased current capacity (130 mA) and lower DC resistance (6Ohm). This part is suitable only where circuit design accommodates the different inductance value.

For non-compliance applications with higher current margin: 1812-124J from API Delevan Inc. maintains 120 µH inductance and 8Ohm DC resistance with 158 mA current rating, supporting the full -55°C ~ 125°C temperature range. RoHS non-compliance status matches the original part.

Frequently Asked Questions (FAQ)

Q: Can CM453232-121JL or CM453232-121KL be used as direct replacements for PM40-121K?

A: Both parts are electrically equivalent with 120 µH inductance, 110 mA current rating, and 8Ohm maximum DC resistance in the same 1812 package. The primary difference is the reduced operating temperature minimum of -40°C versus the original -55°C. Applications operating above -40°C can use these parts without circuit modification. Both offer improved RoHS3 compliance status.

Q: What is the difference between CM453232-121JL and CM453232-121KL?

A: Both parts are functionally equivalent with identical inductance (120 µH), current rating (110 mA), and DC resistance (8Ohm). CM453232-121JL specifies ±5% tolerance while CM453232-121KL specifies ±10% tolerance. Selection depends on circuit tolerance requirements.

Q: Is CM453232-680KL a suitable substitute?

A: CM453232-680KL is not a direct electrical equivalent. It operates at 68 µH inductance instead of 120 µH, with higher current rating (130 mA) and lower DC resistance (6Ohm). This part is suitable only for circuits where the different inductance value is acceptable and the increased current capacity provides design benefit.

Q: Can 1812-124J replace PM40-121K?

A: 1812-124J maintains the 120 µH inductance and 8Ohm DC resistance with enhanced current rating (158 mA). It supports the full -55°C ~ 125°C temperature range. The part is manufactured by a different supplier (API Delevan Inc.) and retains RoHS non-compliance status matching the original. Electrical substitution is valid; supplier qualification may be required.

Q: What are the package compatibility considerations?

A: All substitute parts use the 1812 (4532 Metric) surface mount package with identical footprint dimensions (0.177" L x 0.126" W / 4.50mm x 3.20mm). Height differences exist: PM40-121K is 0.126" (3.20mm) while Bourns CM45 series parts are 0.134" (3.40mm). Verify PCB clearance for height variation before implementation.

Q: Are there RoHS compliance implications for substitution?

A: PM40-121K is RoHS non-compliant. CM453232-121JL, CM453232-121KL, and CM453232-680KL are ROHS3 compliant. 1812-124J is RoHS non-compliant. Substitution with Bourns CM45 series parts improves regulatory compliance status. Verify compliance requirements for your application before selection.