PM43-270M Equivalent & Substitute Parts

Part Overview

The PM43-270M is a 27 µH unshielded drum core wirewound inductor manufactured by Bourns Inc., rated for 620 mA with a DC resistance of 522mOhm. This component operates across -40°C to 100°C and is classified as obsolete. Due to its obsolete status, equivalent and substitute parts from active product lines are necessary to maintain design continuity and ensure long-term component availability for new production runs and field replacements.

Key Parameters

Parameter	PM43-270M
Inductance	27 µH
Current Rating	620 mA
DC Resistance (DCR)	522mOhm
Tolerance	±20%
Shielding	Unshielded
Core Material	Ferrite
Operating Temperature	-40°C ~ 100°C
Mounting Type	Surface Mount
Package Size	0.177" L x 0.157" W x 0.138" H (4.50mm x 4.00mm x 4.60mm)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the PM43-270M is determined by the following critical parameters:

Inductance Value: 27 µH (exact match required)
Current Rating: Minimum 620 mA (equal or higher acceptable)
DC Resistance: Maximum 522mOhm (equal or lower acceptable)
Shielding Configuration: Unshielded (preferred for direct replacement)
Core Material: Ferrite
Mounting Type: Surface Mount
Package Footprint: 4.50mm x 4.00mm x 4.60mm (physical compatibility)
Operating Temperature Range: Minimum -40°C ~ 100°C (equal or wider acceptable)

Substitute parts are categorized as follows:

Direct Equivalent (Same Inductance, Improved Specifications)

SDR0403-270KL: Matches 27 µH inductance with higher current rating (710 mA) and improved tolerance (±10%). Active product status ensures availability.

Similar Functional Alternatives (Different Inductance Values)

SRR1806-100M: 10 µH shielded inductor with significantly higher current capacity (4 A). Not a direct replacement due to different inductance and shielding.
SRR1806-101M: 100 µH shielded inductor with lower current rating (1.3 A). Not a direct replacement due to different inductance and shielding.

Cross-Manufacturer Equivalent (Same Specifications, Different Manufacturer)

CD43NP-270MC: Sumida America Components Inc. equivalent with identical 27 µH inductance, 620 mA rating, and 522mOhm DCR. Active product status and RoHS3 compliance.

Parameter Comparison

Parameter	PM43-270M	SDR0403-270KL	CD43NP-270MC	SRR1806-100M	SRR1806-101M
Manufacturer	Bourns Inc.	Bourns Inc.	Sumida America Components Inc.	Bourns Inc.	Bourns Inc.
Inductance	27 µH	27 µH	27 µH	10 µH	100 µH
Current Rating (Amps)	620 mA	710 mA	620 mA	4 A	1.3 A
DC Resistance (DCR)	522mOhm	520mOhm Max	522mOhm Max	33mOhm	270mOhm
Tolerance	±20%	±10%	±20%	±20%	±20%
Shielding	Unshielded	Unshielded	Unshielded	Shielded	Shielded
Core Material	Ferrite	Ferrite	Ferrite	Ferrite	Ferrite
Operating Temperature	-40°C ~ 100°C	-40°C ~ 125°C	-40°C ~ 100°C	-40°C ~ 125°C	-40°C ~ 125°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package Size (mm)	4.50 x 4.00 x 4.60	4.50 x 4.00 x 4.60	4.50 x 4.00 x 4.60	18.30 x 14.00 x 7.10	18.30 x 14.00 x 7.10
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: SDR0403-270KL

The SDR0403-270KL is the preferred direct substitute for the PM43-270M. Both components share identical inductance (27 µH), matching footprint dimensions (4.50mm x 4.00mm x 4.60mm), and unshielded configuration. The SDR0403-270KL provides improved specifications with higher current rating (710 mA vs. 620 mA), tighter tolerance (±10% vs. ±20%), and extended operating temperature range (-40°C ~ 125°C vs. -40°C ~ 100°C). Active product status ensures long-term availability. ROHS3 compliance addresses regulatory requirements where the original PM43-270M does not.

Secondary Recommendation: CD43NP-270MC

The CD43NP-270MC from Sumida America Components Inc. provides an equivalent cross-manufacturer option with identical electrical specifications (27 µH, 620 mA, 522mOhm DCR) and matching package footprint. This part is suitable for applications where multi-source qualification is required. ROHS3 compliance and active product status support production continuity.

Not Recommended for Direct Replacement: SRR1806-100M and SRR1806-101M

The SRR1806 series parts differ significantly in inductance value and shielding configuration. SRR1806-100M (10 µH) and SRR1806-101M (100 µH) are not functionally equivalent to the 27 µH PM43-270M and require circuit redesign. Additionally, the SRR1806 series uses a larger package footprint (18.30mm x 14.00mm x 7.10mm), which may not fit existing PCB layouts designed for the PM43-270M.

Frequently Asked Questions (FAQ)

Q: Can SDR0403-270KL be used as a direct drop-in replacement for PM43-270M?

A: Yes. The SDR0403-270KL matches the PM43-270M in inductance (27 µH), DC resistance (520mOhm Max vs. 522mOhm), current rating (710 mA exceeds 620 mA requirement), and package footprint (4.50mm x 4.00mm x 4.60mm). The improved tolerance (±10%) and extended temperature range (-40°C ~ 125°C) provide additional design margin.

Q: What is the difference between the PM43-270M and SDR0403-270KL in terms of shielding?

A: Both components are unshielded drum core inductors. Shielding configuration is identical, making them suitable for applications with the same EMI requirements.

Q: Why are SRR1806-100M and SRR1806-101M listed as substitutes if they have different inductance values?

A: These parts are listed based on the provided substitute list but are not recommended for direct replacement. They serve different circuit functions due to their different inductance values (10 µH and 100 µH respectively) and shielded configuration. Circuit redesign would be required to use these alternatives.

Q: Is CD43NP-270MC compatible with existing PM43-270M designs?

A: Yes. The CD43NP-270MC provides identical electrical specifications (27 µH, 620 mA, 522mOhm DCR) and matching package footprint. It is suitable for applications requiring cross-manufacturer qualification or where Sumida components are preferred.

Q: What is the impact of the PM43-270M being obsolete?

A: The obsolete status means Bourns Inc. no longer manufactures this component. SDR0403-270KL and CD43NP-270MC are active products with confirmed availability, making them necessary for new production and long-term field support.

Q: Does the improved tolerance of SDR0403-270KL (±10% vs. ±20%) affect circuit performance?

A: Tighter tolerance provides improved inductance consistency across production batches, which can enhance circuit stability and reduce performance variation. This is beneficial for applications sensitive to inductance drift.

Q: Are there any thermal considerations when switching from PM43-270M to SDR0403-270KL?

A: The SDR0403-270KL operates across -40°C ~ 125°C compared to PM43-270M's -40°C ~ 100°C range. This extended range provides additional thermal margin for applications operating at elevated temperatures.

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