PM40-R56M Equivalent & Substitute Parts

Part Overview

The PM40-R56M is a 560 nH unshielded molded inductor manufactured by Bourns Inc., rated for 450 mA with a maximum DC resistance of 550 mOhm. This component is packaged in the 1812 (4532 Metric) surface mount form factor and operates across the temperature range of -55°C to 125°C. The part is currently obsolete, necessitating identification of equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and repair applications.

Key Parameters

Parameter	PM40-R56M
Inductance	560 nH
Inductance Tolerance	±20%
Current Rating	450 mA
DC Resistance (DCR)	550 mOhm Max
Package / Case	1812 (4532 Metric)
Mounting Type	Surface Mount
Operating Temperature	-55°C ~ 125°C
Shielding	Unshielded
Q @ Frequency	30 @ 25.2 MHz
Frequency - Self Resonant	180 MHz

Substitute Part Grouping Explanation

Substitution eligibility for the PM40-R56M is determined by the following critical parameters:

Inductance Value: 560 nH (exact match required)
Package / Case: 1812 (4532 Metric) surface mount form factor (exact match required)
Current Rating: Minimum 450 mA (equal or greater acceptable)
DC Resistance: Maximum 550 mOhm (lower values acceptable)
Operating Temperature Range: Must encompass or exceed -55°C ~ 125°C
Shielding Configuration: Unshielded (as specified)

The substitute parts identified below meet these core electrical and mechanical requirements while offering improvements in certain performance characteristics or compliance status.

Parameter Comparison

Parameter	PM40-R56M	CM453232-R56KL	CM453232-R56ML	1812-561K
Manufacturer	Bourns Inc.	Bourns Inc.	Bourns Inc.	API Delevan Inc.
Inductance	560 nH	560 nH	560 nH	560 nH
Inductance Tolerance	±20%	±10%	±20%	±10%
Current Rating (Amps)	450 mA	520 mA	520 mA	409 mA
DC Resistance (DCR)	550 mOhm Max	360 mOhm Max	360 mOhm Max	1.2 Ohm Max
Package / Case	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Operating Temperature	-55°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-55°C ~ 125°C
Shielding	Unshielded	Unshielded	Unshielded	Unshielded
Q @ Frequency	30 @ 25.2 MHz	40 @ 25.2 MHz	40 @ 25.2 MHz	30 @ 25 MHz
Frequency - Self Resonant	180 MHz	140 MHz	140 MHz	170 MHz
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant

Engineering Selection Recommendations

CM453232-R56KL and CM453232-R56ML are direct substitutes manufactured by Bourns Inc. Both parts maintain the 560 nH inductance value and 1812 package form factor. These alternatives offer improved DC resistance (360 mOhm versus 550 mOhm), higher current ratings (520 mA versus 450 mA), and superior Q factor (40 versus 30 at 25.2 MHz). Both are ROHS3 compliant, addressing regulatory requirements. The CM453232-R56KL features ±10% inductance tolerance, while CM453232-R56ML maintains ±20% tolerance matching the original specification. The operating temperature range of -40°C to 125°C covers most applications; however, designs requiring -55°C operation must account for this limitation.

1812-561K manufactured by API Delevan Inc. maintains the full -55°C to 125°C operating temperature range and ±10% inductance tolerance. However, the DC resistance of 1.2 Ohm significantly exceeds the original 550 mOhm specification and the 409 mA current rating falls below the 450 mA requirement. This part is suitable only for applications where higher DC resistance and lower current capacity are acceptable.

For new designs and production requiring regulatory compliance, CM453232-R56ML is the preferred substitute, offering active product status, ROHS3 compliance, and electrical performance improvements over the obsolete PM40-R56M.

Frequently Asked Questions (FAQ)

Q: Can CM453232-R56KL and CM453232-R56ML be used interchangeably with PM40-R56M?

A: Both Bourns CM45 series parts are electrically and mechanically compatible with PM40-R56M. The primary difference is inductance tolerance: CM453232-R56KL provides ±10% tolerance while CM453232-R56ML matches the original ±20% specification. Both offer superior DC resistance and current ratings.

Q: What is the impact of the -40°C lower operating temperature limit on CM453232 parts?

A: The CM453232 series operates from -40°C to 125°C, compared to PM40-R56M's -55°C to 125°C range. Applications requiring operation below -40°C must use alternative parts such as 1812-561K, which maintains the full -55°C specification.

Q: Why does 1812-561K have significantly higher DC resistance?

A: The 1812-561K uses an iron core construction, resulting in 1.2 Ohm DC resistance compared to 360-550 mOhm in molded and ferrite core designs. This characteristic affects power dissipation and thermal performance in the circuit.

Q: Are all substitute parts available in the same packaging format?

A: Yes. PM40-R56M and all identified substitutes use the 1812 (4532 Metric) surface mount package with identical footprint dimensions of 0.177" L x 0.126" W (4.50mm x 3.20mm), ensuring PCB compatibility.

Q: What compliance certifications apply to each part?

A: CM453232-R56KL and CM453232-R56ML are ROHS3 compliant. PM40-R56M and 1812-561K are RoHS non-compliant. All parts are REACH unaffected and classified as EAR99 for export control purposes.

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