PM43-390K Equivalent & Substitute Parts

Part Overview

The PM43-390K is a 39 µH unshielded drum core wirewound inductor manufactured by Bourns Inc., rated for 520 mA with 587mOhm DC resistance. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The part operates across -40°C to 100°C and is mounted as a surface mount nonstandard package component.

Key Parameters

Parameter	Value
Inductance	39 µH
Inductance Tolerance	±10%
Current Rating	520 mA
DC Resistance (DCR)	587mOhm
Core Material	Ferrite
Shielding	Unshielded
Operating Temperature Range	-40°C ~ 100°C
Mounting Type	Surface Mount
Physical Dimensions	4.50mm L x 4.00mm W x 4.60mm H
Self Resonant Frequency	18 MHz

Substitute Part Grouping Explanation

Substitution eligibility for the PM43-390K is determined by the following critical parameters: inductance value (39 µH ±10%), current rating capability (minimum 520 mA), DC resistance (587mOhm maximum), core material (ferrite), shielding configuration (unshielded), and physical footprint compatibility (4.50mm x 4.00mm x 4.60mm maximum).

Substitute parts are categorized into two groups:

Direct Substitutes maintain identical or superior electrical performance within the specified tolerance band and physical constraints. These parts are pin-compatible and functionally interchangeable without circuit redesign.

Similar Substitutes share the same inductance value and current rating but may differ in secondary parameters such as DC resistance, manufacturer, or physical dimensions. These require verification of circuit-level compatibility before implementation.

Parameter Comparison

Part Number	Manufacturer	Inductance	Current Rating	DCR (mOhm)	Shielding	Dimensions (mm)	Operating Temp	Product Status	RoHS Compliance
PM43-390K	Bourns Inc.	39 µH ±10%	520 mA	587	Unshielded	4.50 x 4.00 x 4.60	-40°C ~ 100°C	Obsolete	Non-compliant
SDR0403-390KL	Bourns Inc.	39 µH ±10%	590 mA	590 Max	Unshielded	4.50 x 4.00 x 4.60	-40°C ~ 125°C	Active	ROHS3 Compliant
CD43NP-390KC	Sumida America Components Inc.	39 µH ±10%	520 mA	587 Max	Unshielded	4.50 x 4.00 x 4.60	-40°C ~ 100°C	Active	ROHS3 Compliant
CR43NP-390KC	Sumida America Components Inc.	39 µH ±10%	520 mA	587 Max	Unshielded	4.80 x 4.30 x 4.60	-40°C ~ 100°C	Active	ROHS3 Compliant
SRR1806-330M	Bourns Inc.	33 µH ±20%	2.5 A	83	Shielded	18.30 x 14.00 x 7.10	-40°C ~ 125°C	Active	ROHS3 Compliant
SRR1806-221M	Bourns Inc.	220 µH ±20%	1 A	510	Shielded	18.30 x 14.00 x 7.10	-40°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: SDR0403-390KL

The SDR0403-390KL from Bourns Inc. is the optimal direct substitute for the PM43-390K. This part maintains identical inductance (39 µH ±10%), exceeds the current rating requirement (590 mA versus 520 mA), and preserves the unshielded drum core configuration and physical footprint. The SDR0403-390KL is active in production status with ROHS3 compliance, addressing the regulatory limitations of the obsolete PM43-390K. Extended operating temperature range (-40°C to 125°C) provides additional thermal margin.

Secondary Recommendations: CD43NP-390KC and CR43NP-390KC

Both Sumida America Components Inc. parts (CD43NP-390KC and CR43NP-390KC) provide electrical equivalence to the PM43-390K with identical inductance, current rating, and DC resistance specifications. Both are active production parts with ROHS3 compliance. The CR43NP-390KC exhibits a slightly larger footprint (4.80mm x 4.30mm versus 4.50mm x 4.00mm) and requires physical layout verification. The CD43NP-390KC maintains the original footprint dimensions.

Not Recommended for Direct Substitution: SRR1806-330M and SRR1806-221M

The SRR1806 series parts deviate significantly from the PM43-390K specification. SRR1806-330M offers 33 µH (outside the ±10% tolerance band) with substantially different physical dimensions (18.30mm x 14.00mm). SRR1806-221M provides 220 µH, representing a 5.6x inductance increase. Both employ shielded construction and are incompatible with the original circuit topology without redesign.

Frequently Asked Questions (FAQ)

Q: Can SDR0403-390KL be used as a direct replacement without circuit modification?

A: Yes. The SDR0403-390KL maintains the same inductance value (39 µH ±10%), physical footprint (4.50mm x 4.00mm x 4.60mm), and unshielded configuration as the PM43-390K. The higher current rating (590 mA) and extended temperature range provide additional design margin.

Q: What is the difference between the CD43NP-390KC and CR43NP-390KC?

A: Both parts share identical electrical specifications (39 µH, 520 mA, 587mOhm DCR). The CR43NP-390KC has a slightly larger footprint (4.80mm x 4.30mm versus 4.50mm x 4.00mm). Physical layout compatibility must be verified before selection.

Q: Why are SRR1806-330M and SRR1806-221M listed as substitutes if they have different inductance values?

A: These parts are listed based on the original PM43-390K data provided but are not suitable substitutes due to inductance deviation outside the ±10% tolerance specification and shielded construction incompatible with the original unshielded design.

Q: Does RoHS compliance affect electrical performance?

A: No. RoHS3 compliance indicates manufacturing process changes to eliminate restricted substances but does not alter the electrical characteristics of the inductor. The compliance status is relevant for regulatory and procurement requirements.

Q: What is the significance of the ±10% inductance tolerance?

A: The ±10% tolerance defines the acceptable inductance range (35.1 µH to 42.9 µH). Substitute parts must maintain this tolerance band to ensure circuit performance. The SRR1806 series with ±20% tolerance falls outside this specification.

Q: Can the PM43-390K be replaced with a higher current-rated part?

A: Yes, provided all other parameters remain compatible. The SDR0403-390KL (590 mA rating) and Sumida parts (520 mA rating) are acceptable. Higher current ratings provide design margin without compromising circuit function.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message