PM40-6R8K Equivalent & Substitute Parts

Part Overview

The PM40-6R8K is a 6.8 µH unshielded molded inductor manufactured by Bourns Inc., rated for 285 mA with a maximum DC resistance of 1.2Ohm in a 1812 (4532 Metric) surface mount package. This component operates across a temperature range of -55°C to 125°C and is classified as obsolete. Due to its obsolete status, equivalent and substitute parts from active product lines are necessary for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value
Inductance	6.8 µH
Inductance Tolerance	±10%
Current Rating	285 mA
DC Resistance (Max)	1.2Ohm
Package / Case	1812 (4532 Metric)
Mounting Type	Surface Mount
Operating Temperature Range	-55°C ~ 125°C
Q @ Frequency	50 @ 7.96MHz
Self Resonant Frequency	27MHz
Shielding	Unshielded

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict alignment with the following critical parameters: inductance value (6.8 µH), current rating (285 mA minimum), DC resistance (1.2Ohm maximum), package type (1812/4532 Metric), and surface mount configuration. All substitute parts must maintain these electrical and mechanical specifications to ensure functional compatibility.

The substitute parts are categorized as follows:

Direct Substitutes (Bourns CM45 Series): CM453232-6R8JL and CM453232-6R8KL meet all electrical requirements and package specifications. Both are active products with improved RoHS3 compliance compared to the obsolete PM40-6R8K.

Similar Substitutes (Alternative Manufacturers): 1812-682J (API Delevan Inc.) and 74476606 (Würth Elektronik) meet the core electrical parameters but with noted variations in current rating and operating temperature range.

Parameter Comparison

Parameter	PM40-6R8K	CM453232-6R8JL	CM453232-6R8KL	1812-682J	74476606
Manufacturer	Bourns Inc.	Bourns Inc.	Bourns Inc.	API Delevan Inc.	Würth Elektronik
Series	PM40	CM45	CM45	1812	WE-GF
Inductance	6.8 µH	6.8 µH	6.8 µH	6.8 µH	6.8 µH
Inductance Tolerance	±10%	±5%	±10%	±5%	±10%
Current Rating (mA)	285	285	285	409	285
DC Resistance (Max)	1.2Ohm	1.2Ohm	1.2Ohm	1.2Ohm	1.2Ohm
Package / Case	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)	1812 (4532 Metric)
Mounting Type	Surface Mount	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	-40°C ~ 105°C
Q @ Frequency	50 @ 7.96MHz	50 @ 7.96MHz	50 @ 7.96MHz	50 @ 7.9MHz	50 @ 7.96MHz
Self Resonant Frequency	27MHz	27MHz	27MHz	27MHz	35MHz
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	Non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

Preferred Substitutes: CM453232-6R8JL and CM453232-6R8KL are the primary recommendations. Both are active Bourns products with ROHS3 compliance, matching all critical electrical parameters of the PM40-6R8K. CM453232-6R8JL offers tighter inductance tolerance (±5%) compared to the original part (±10%), while CM453232-6R8KL maintains the original ±10% tolerance. The primary distinction between these two is packaging format: CM453232-6R8JL is supplied in Tape & Reel, while CM453232-6R8KL is available in Cut Tape & Digi-Reel format.

Alternative Substitutes: 1812-682J (API Delevan Inc.) and 74476606 (Würth Elektronik) are viable alternatives when Bourns products are unavailable. The 1812-682J provides a higher current rating (409 mA) and maintains the full -55°C to 125°C temperature range of the original part, though it lacks RoHS3 compliance. The 74476606 offers RoHS3 compliance and a higher self-resonant frequency (35MHz), but operates only to 105°C maximum, which may be limiting in applications requiring the full 125°C upper temperature limit.

Frequently Asked Questions (FAQ)

Q: Can CM453232-6R8JL and CM453232-6R8KL be used interchangeably with PM40-6R8K?

A: Yes. Both parts meet all critical electrical specifications: 6.8 µH inductance, 285 mA current rating, 1.2Ohm maximum DC resistance, and 1812 package configuration. The primary differences are packaging format and inductance tolerance. CM453232-6R8JL provides ±5% tolerance versus the original ±10%, which may improve circuit performance in applications sensitive to inductance variation.

Q: What is the impact of the lower operating temperature minimum (-40°C vs. -55°C) for the CM45 series?

A: The CM45 series operates from -40°C to 125°C, compared to the PM40-6R8K range of -55°C to 125°C. Applications requiring operation below -40°C must use either the 1812-682J (API Delevan) or remain with the original PM40-6R8K if available. For most commercial and industrial applications, the -40°C minimum is sufficient.

Q: How do the packaging options affect component selection?

A: CM453232-6R8JL is supplied in Tape & Reel (TR) format, suitable for high-volume automated assembly. CM453232-6R8KL is available in Cut Tape (CT) & Digi-Reel format, appropriate for lower-volume or mixed-component orders. Both formats contain identical electrical components; selection depends on procurement volume and assembly line requirements.

Q: Is RoHS3 compliance a critical factor for this substitution?

A: RoHS3 compliance is determined by application requirements and regional regulations. CM453232-6R8JL, CM453232-6R8KL, and 74476606 are all ROHS3 compliant. If RoHS3 compliance is mandatory, these three parts are preferred over 1812-682J and the obsolete PM40-6R8K.

Q: What is the significance of the higher self-resonant frequency in the 74476606?

A: The 74476606 (Würth Elektronik) has a self-resonant frequency of 35MHz compared to 27MHz for other parts. This higher frequency may provide improved performance in high-frequency applications, but the reduced maximum operating temperature (105°C) may be a limiting factor in thermal-constrained designs.

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