PM20S-270K Equivalent & Substitute Parts

Part Overview

The PM20S-270K is a 27 µH shielded molded inductor manufactured by Bourns Inc., rated for 125 mA with a maximum DC resistance of 3.3Ohm. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The part is housed in a 1210 (3225 Metric) surface mount package and operates across the temperature range of -55°C to 125°C.

Key Parameters

Parameter	Value
Inductance	27 µH
Tolerance	±10%
Current Rating	125 mA
DC Resistance (DCR)	3.3Ohm Max
Shielding	Shielded
Package / Case	1210 (3225 Metric)
Operating Temperature	-55°C ~ 125°C
Mounting Type	Surface Mount
Q @ Freq	30 @ 2.52MHz
Frequency - Self Resonant	14MHz

Substitute Part Grouping Explanation

Substitution eligibility for the PM20S-270K is determined by the following critical parameters:

Primary Matching Criteria:

Inductance value: 27 µH
Inductance tolerance: ±10% or tighter
Current rating: minimum 125 mA
DC resistance: maximum 3.3Ohm
Package / Case: 1210 (3225 Metric)
Shielding: Shielded configuration
Operating temperature range: -55°C ~ 125°C minimum

Substitute parts are grouped into two categories based on core material and construction type:

Category A - Iron Powder Core (Vishay Dale ISC-1210 Series): Parts ISC1210BN270K, ISC1210EB270K, ISC1210ER270K, and ISC1210SY270K maintain identical electrical specifications (27 µH, 125 mA, 3.3Ohm DCR) with drum core wirewound construction. These provide direct functional equivalence with variations in packaging format and RoHS compliance status.

Category B - Ferrite Core (API Delevan S1210 Series): Part S1210-273K offers 27 µH inductance with higher current rating (201 mA) and slightly elevated DCR (4Ohm Max), suitable for applications with relaxed DC resistance tolerance.

Non-Equivalent Parts: CM322522-270JL and CM322522-270KL are unshielded drum core inductors with reduced current rating (90 mA) and higher DCR (5Ohm Max), making them unsuitable as direct substitutes for shielded applications requiring 125 mA operation.

Parameter Comparison

Part Number	Manufacturer	Inductance	Tolerance	Current Rating (mA)	DCR (Ohm Max)	Shielding	Core Material	Package	Operating Temp	Product Status	RoHS Status
PM20S-270K	Bourns Inc.	27 µH	±10%	125	3.3	Shielded	Ferrite	1210	-55°C ~ 125°C	Obsolete	RoHS non-compliant
ISC1210BN270K	Vishay Dale	27 µH	±10%	125	3.3	Shielded	Iron Powder	1210	-55°C ~ 125°C	Active	RoHS non-compliant
ISC1210EB270K	Vishay Dale	27 µH	±10%	125	3.3	Shielded	Iron Powder	1210	-55°C ~ 125°C	Active	ROHS3 Compliant
ISC1210ER270K	Vishay Dale	27 µH	±10%	125	3.3	Shielded	Iron Powder	1210	-55°C ~ 125°C	Active	ROHS3 Compliant
ISC1210SY270K	Vishay Dale	27 µH	±10%	125	3.3	Shielded	Iron Powder	1210	-55°C ~ 125°C	Active	RoHS non-compliant
S1210-273K	API Delevan Inc.	27 µH	±10%	201	4	Shielded	Ferrite	1210	-55°C ~ 125°C	Active	RoHS non-compliant
CM322522-270JL	Bourns Inc.	27 µH	±5%	90	5	Unshielded	Ferrite	Nonstandard	-40°C ~ 125°C	Active	ROHS3 Compliant
CM322522-270KL	Bourns Inc.	27 µH	±10%	90	5	Unshielded	Ferrite	Nonstandard	-40°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Preferred Substitutes (Direct Equivalents):

ISC1210EB270K and ISC1210ER270K are the primary recommended substitutes. Both maintain identical electrical specifications (27 µH, 125 mA, 3.3Ohm DCR) and package dimensions, with the advantage of active product status and ROHS3 compliance. ISC1210EB270K is available in bulk packaging, while ISC1210ER270K is supplied in tape and reel format for automated assembly.

Alternative Substitutes (Functional Equivalents):

ISC1210BN270K and ISC1210SY270K provide identical electrical performance and package compatibility. ISC1210BN270K offers bulk packaging with REACH affected status. ISC1210SY270K is available in tape and reel format but carries RoHS non-compliant status, matching the original PM20S-270K compliance profile.

Secondary Option (Relaxed Specifications):

S1210-273K from API Delevan Inc. is suitable for applications where increased current margin (201 mA vs. 125 mA) and slightly elevated DC resistance (4Ohm vs. 3.3Ohm) are acceptable. This part maintains shielding, package size, and temperature range compatibility.

Not Recommended:

CM322522-270JL and CM322522-270KL are unsuitable substitutes due to unshielded construction, reduced current rating (90 mA), elevated DC resistance (5Ohm), and nonstandard package dimensions.

Frequently Asked Questions (FAQ)

Q: Can ISC1210EB270K directly replace PM20S-270K in existing designs?

A: Yes. ISC1210EB270K matches all critical electrical parameters (27 µH inductance, 125 mA current rating, 3.3Ohm maximum DCR) and is housed in the identical 1210 (3225 Metric) package. The primary difference is core material (iron powder vs. ferrite) and active product status, which provides long-term availability assurance.

Q: What is the difference between ISC1210ER270K and ISC1210EB270K?

A: Both parts are electrically and mechanically identical. The difference is packaging format: ISC1210ER270K is supplied in tape and reel (TR) format for automated pick-and-place assembly, while ISC1210EB270K is supplied in bulk format. Selection depends on assembly process requirements.

Q: Why are CM322522-270JL and CM322522-270KL listed as non-equivalent?

A: These parts are unshielded inductors with current rating of 90 mA, which is insufficient for the 125 mA requirement of the original PM20S-270K. Additionally, their DC resistance (5Ohm maximum) exceeds the 3.3Ohm specification, and they use nonstandard package dimensions incompatible with 1210 footprints.

Q: Is S1210-273K suitable for my application?

A: S1210-273K is suitable only if your circuit design can tolerate increased current margin (201 mA available vs. 125 mA required) and slightly higher DC resistance (4Ohm vs. 3.3Ohm). The part maintains shielding, package size, and temperature range. Verify that the elevated DCR does not impact circuit performance before selection.

Q: What is the impact of switching from ferrite core (PM20S-270K) to iron powder core (ISC-1210 series)?

A: Both core materials provide the specified 27 µH inductance and 125 mA current rating. Iron powder cores typically exhibit different frequency response characteristics and temperature stability compared to ferrite cores. Verify frequency-dependent performance in your specific application, particularly if operating near the self-resonant frequency (14MHz for PM20S-270K vs. 14.5MHz for ISC-1210 series).

Q: Are there RoHS compliance considerations for substitute selection?

A: Yes. The original PM20S-270K is RoHS non-compliant. If your application requires RoHS3 compliance, select ISC1210EB270K or ISC1210ER270K. If RoHS compliance is not required, all Vishay Dale ISC-1210 variants and API Delevan S1210-273K are available options.

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