PM40-331K Equivalent & Substitute Parts

Part Overview

The PM40-331K is a 330 µH unshielded molded inductor manufactured by Bourns Inc., rated for 85 mA with a maximum DC resistance of 20 Ohm in a 1812 (4532 Metric) surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Inductance	330 µH
Current Rating	85 mA
DC Resistance (DCR)	20 Ohm Max
Tolerance	±10%
Package / Case	1812 (4532 Metric)
Mounting Type	Surface Mount
Operating Temperature	-55°C ~ 125°C
Shielding	Unshielded

Substitute Part Grouping Explanation

Substitution for the PM40-331K is determined by the following critical parameters: inductance value (330 µH), current rating (85 mA minimum), package type (1812 surface mount), and DC resistance performance. The substitute parts are grouped into two categories:

Direct Substitutes (Electrical & Mechanical Compatibility): Parts CM453232-331JL and CM453232-331KL maintain the same inductance (330 µH), current rating (85 mA), and package dimensions. These parts feature improved DC resistance (14 Ohm Max versus 20 Ohm Max) and higher Q factor (40 @ 796kHz versus 30 @ 796kHz), with active product status and RoHS3 compliance.

Similar Substitute (Different Inductance): Part CM453232-R68ML shares the same package and manufacturer but operates at a different inductance value (680 nH) and current rating (500 mA), making it unsuitable for direct replacement in circuits requiring 330 µH inductance.

Cross-Manufacturer Alternatives: Parts PM1812-331J-RC (Bourns) and 1812-334J (API Delevan) provide 330 µH inductance with 85 mA or higher current ratings in the same package, offering alternative sourcing options with active product status.

Parameter Comparison

Parameter	PM40-331K	CM453232-331JL	CM453232-331KL	PM1812-331J-RC	1812-334J
Inductance	330 µH	330 µH	330 µH	330 µH	330 µH
Current Rating (Amps)	85 mA	85 mA	85 mA	85 mA	120 mA
DC Resistance (DCR)	20 Ohm Max	14 Ohm Max	14 Ohm Max	14 Ohm Max	14 Ohm Max
Tolerance	±10%	±5%	±10%	±5%	±5%
Q @ Freq	30 @ 796kHz	40 @ 796kHz	40 @ 796kHz	40 @ 796kHz	40 @ 790kHz
Frequency - Self Resonant	3 MHz	4.6 MHz	4.6 MHz	4.6 MHz	4.6 MHz
Operating Temperature	-55°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 100°C	-55°C ~ 125°C
Package / Case	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant

Engineering Selection Recommendations

For applications requiring direct replacement of the PM40-331K, CM453232-331JL and CM453232-331KL are the primary substitutes. Both parts maintain electrical equivalence with improved performance characteristics (lower DCR and higher Q factor) and carry active product status with RoHS3 compliance, supporting modern supply chain and environmental requirements.

PM1812-331J-RC offers an alternative from Bourns with active status and RoHS3 compliance, though its maximum operating temperature is limited to 100°C compared to the original part's 125°C upper limit.

The 1812-334J from API Delevan provides higher current rating capability (120 mA) and matches the original operating temperature range (-55°C ~ 125°C), but does not carry RoHS3 compliance.

CM453232-R68ML is not suitable for direct replacement due to its different inductance value (680 nH) and current rating (500 mA).

Frequently Asked Questions (FAQ)

Q: Can CM453232-331JL and CM453232-331KL be used interchangeably with PM40-331K?

A: Yes. Both parts maintain the same inductance (330 µH), current rating (85 mA), and 1812 package dimensions. The primary differences are improved DC resistance (14 Ohm Max versus 20 Ohm Max) and higher Q factor, which are performance enhancements. Packaging differs between Tape & Reel (CM453232-331JL) and Cut Tape & Digi-Reel (CM453232-331KL).

Q: What is the impact of lower DC resistance in substitute parts?

A: Lower DC resistance (14 Ohm Max in substitutes versus 20 Ohm Max in PM40-331K) reduces power dissipation and heat generation in the inductor, improving overall circuit efficiency. This is a beneficial characteristic for direct replacement.

Q: Are there temperature range limitations with substitute parts?

A: CM453232-331JL, CM453232-331KL, and PM1812-331J-RC operate at -40°C minimum, compared to the PM40-331K's -55°C minimum. For applications requiring operation below -40°C, the original part or 1812-334J (which supports -55°C) must be used.

Q: What is the difference between the two CM453232 variants?

A: CM453232-331JL and CM453232-331KL are electrically identical with the same inductance, current rating, and DC resistance. The difference is packaging: CM453232-331JL is supplied in Tape & Reel format, while CM453232-331KL is supplied in Cut Tape & Digi-Reel format. Select based on procurement and assembly requirements.

Q: Why is CM453232-R68ML listed as a substitute if it has different specifications?

A: CM453232-R68ML is not a direct substitute. It is listed as a related part from the same manufacturer and package family but with different inductance (680 nH) and current rating (500 mA). It is unsuitable for circuits designed for 330 µH inductance.

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