PM54-121K Equivalent & Substitute Parts

Part Overview

The PM54-121K is a 120 µH unshielded drum core wirewound inductor manufactured by Bourns Inc., rated for 480 mA with 930mOhm DC resistance. This part is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. The PM54 series has been superseded by more modern alternatives that maintain electrical compatibility while offering improved availability and compliance status.

Key Parameters

Parameter	Value
Inductance	120 µH
Tolerance	±10%
Current Rating	480 mA
DC Resistance (DCR)	930mOhm
Core Material	Ferrite
Shielding	Unshielded
Mounting Type	Surface Mount
Operating Temperature Range	-30°C ~ 100°C
Package Type	Nonstandard
Physical Dimensions	5.80mm x 5.80mm x 4.80mm (max height)

Substitute Part Grouping Explanation

Substitution eligibility for the PM54-121K is determined by the following critical parameters:

Inductance Value: Must be 120 µH ±10%
Current Rating: Minimum 480 mA
DC Resistance: Maximum 930mOhm
Core Material: Ferrite
Shielding Configuration: Unshielded
Mounting Type: Surface Mount
Physical Footprint: Compatible with 5.80mm x 5.80mm base dimensions

All substitute parts listed meet these core electrical and mechanical requirements. Variations in operating temperature range, saturation current, and compliance certifications are noted but do not disqualify substitution eligibility.

Parameter Comparison

Parameter	PM54-121K (Bourns)	SDR0604-121KL (Bourns)	744774212 (Würth Elektronik)	CD54NP-121KC (Sumida)	PD54R-124K (Delevan)
Inductance	120 µH	120 µH	120 µH	120 µH	120 µH
Tolerance	±10%	±10%	±10%	±10%	±10%
Current Rating (Amps)	480 mA	480 mA	490 mA	480 mA	460 mA
DC Resistance (DCR)	930mOhm	930mOhm Max	930mOhm Max	930mOhm Max	850mOhm Max
Core Material	Ferrite	Ferrite	Ferrite	Ferrite	Ferrite
Shielding	Unshielded	Unshielded	Unshielded	Unshielded	Unshielded
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Operating Temperature	-30°C ~ 100°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 100°C	-55°C ~ 125°C
Product Status	Obsolete	Active	Active	Active	Active
RoHS Compliance	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: SDR0604-121KL (Bourns Inc.)

The SDR0604-121KL is the direct successor within the Bourns product line. It maintains identical electrical specifications (120 µH, 480 mA, 930mOhm DCR) while offering an extended operating temperature range (-40°C ~ 125°C), ROHS3 compliance, and active product status with high inventory availability (6100 pcs). This part is the preferred direct replacement for the obsolete PM54-121K.

Secondary Recommendations:

744774212 (Würth Elektronik): Suitable for applications requiring slightly higher current margin (490 mA rating). Offers extended temperature range and ROHS3 compliance. Dimensions vary slightly (5.80mm x 5.20mm).
CD54NP-121KC (Sumida America): Maintains exact current rating (480 mA) and DCR specification. ROHS3 compliant with active status. Footprint dimensions differ (5.80mm x 5.20mm).
PD54R-124K (Delevan): Acceptable for applications with lower current requirements (460 mA minimum). Offers lowest DCR (850mOhm max) and widest temperature range (-55°C ~ 125°C). ROHS3 compliant.

Selection should prioritize SDR0604-121KL for direct compatibility. Alternative selections depend on specific application requirements regarding current headroom, temperature extremes, and PCB layout constraints.

Frequently Asked Questions (FAQ)

Q: Can the PM54-121K be directly replaced with SDR0604-121KL?

A: Yes. Both parts share identical inductance (120 µH), current rating (480 mA), and DC resistance (930mOhm). Physical dimensions and mounting type are compatible. SDR0604-121KL offers improved compliance and extended temperature range.

Q: What is the difference between the Würth Elektronik 744774212 and the Bourns SDR0604-121KL?

A: Both parts meet the core electrical requirements. The Würth part offers 10 mA higher current rating (490 mA vs 480 mA) and slightly different physical dimensions (5.80mm x 5.20mm vs 5.80mm x 5.80mm). Selection depends on PCB layout constraints and current margin requirements.

Q: Is the Delevan PD54R-124K suitable as a substitute?

A: The PD54R-124K meets inductance, tolerance, and core material requirements. However, its current rating (460 mA) is below the original specification (480 mA). This part is acceptable only for applications where the actual operating current does not exceed 460 mA.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts listed (SDR0604-121KL, 744774212, CD54NP-121KC, PD54R-124K) are ROHS3 compliant. The original PM54-121K is RoHS non-compliant.

Q: Do the substitute parts have different operating temperature ranges?

A: Yes. The original PM54-121K operates from -30°C to 100°C. Substitute parts offer extended ranges: SDR0604-121KL and 744774212 (-40°C ~ 125°C), CD54NP-121KC (-40°C ~ 100°C), and PD54R-124K (-55°C ~ 125°C). Selection should match application temperature requirements.

Q: What is the significance of DC Resistance (DCR) in substitution?

A: DCR directly affects power dissipation and thermal performance. The PM54-121K specifies 930mOhm. All substitutes maintain this specification at maximum (930mOhm max), except PD54R-124K which offers lower DCR (850mOhm max). Lower DCR reduces heat generation in current-limited applications.

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