1812-684K Fixed Inductor Equivalent & Substitute Parts

Part Overview

The 1812-684K is a 680 µH unshielded ferrite core inductor manufactured by API Delevan Inc., designed for surface mount applications in the 1812 package format. This component operates across an industrial temperature range of -55°C to 125°C with a maximum DC resistance of 30 Ohm and a current rating of 82 mA. The part maintains Active product status and is RoHS non-compliant. Substitute parts are identified to address inventory availability, packaging preferences, or specific application requirements while maintaining core electrical and mechanical compatibility.

Key Parameters

Parameter	Value	Unit
Inductance	680	µH
Inductance Tolerance	±10%	—
Current Rating	82	mA
DC Resistance (Max)	30	Ohm
Core Material	Ferrite	—
Shielding	Unshielded	—
Q Factor @ Test Frequency	30 @ 790 kHz	—
Self Resonant Frequency	3	MHz
Operating Temperature Range	-55 to 125	°C
Package / Case	2-SMD / 1812	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the 1812-684K are identified based on strict electrical and mechanical parameter alignment. The primary substitution criterion is inductance value at the specified test frequency, which must be 680 µH ±10%. Secondary criteria include DC resistance maximum of 30 Ohm, ferrite core material, unshielded construction, and surface mount compatibility in the 1812 package format.

The CM453232-681KL from Bourns Inc. qualifies as a substitute based on the following matched parameters:

Inductance: 680 µH ±10%
DC Resistance (Max): 30 Ohm
Core Material: Ferrite
Shielding: Unshielded
Package: 1812 (4532 Metric)
Mounting Type: Surface Mount
Self Resonant Frequency: 3 MHz
Q Factor: 30 @ 796 kHz
Moisture Sensitivity Level: 1 (Unlimited)

The substitute part operates within the same frequency test band (796 kHz vs. 790 kHz) and maintains equivalent electrical performance characteristics. Physical dimensions differ slightly due to drum core construction, which affects length and height but maintains compatibility with 1812 footprint requirements.

Parameter Comparison

Parameter	1812-684K (API Delevan)	CM453232-681KL (Bourns)	Compatibility
Inductance	680 µH	680 µH	Matched
Inductance Tolerance	±10%	±10%	Matched
Current Rating	82 mA	50 mA	Substitute rated lower
DC Resistance (Max)	30 Ohm	30 Ohm	Matched
Core Material	Ferrite	Ferrite	Matched
Shielding	Unshielded	Unshielded	Matched
Q @ Test Frequency	30 @ 790 kHz	30 @ 796 kHz	Equivalent
Self Resonant Frequency	3 MHz	3 MHz	Matched
Operating Temperature	-55 to 125°C	-40 to 125°C	Substitute range narrower
Package / Case	1812 (2-SMD)	1812 (4532 Metric)	Matched footprint
Size / Dimension (L × W)	0.126" × 0.126" (3.20 × 3.20 mm)	0.177" × 0.126" (4.50 × 3.20 mm)	Length differs
Height (Max)	0.190" (4.83 mm)	0.134" (3.40 mm)	Substitute lower profile
Moisture Sensitivity	1 (Unlimited)	1 (Unlimited)	Matched
RoHS Status	Non-compliant	ROHS3 Compliant	Substitute compliant

Engineering Selection Recommendations

Current Rating Consideration: The 1812-684K carries an 82 mA current rating, while the CM453232-681KL is rated for 50 mA. Applications requiring the full 82 mA capability cannot use the substitute without thermal or performance degradation risk. Applications operating below 50 mA are compatible with the substitute.

Temperature Range Consideration: The 1812-684K operates from -55°C to 125°C, while the CM453232-681KL operates from -40°C to 125°C. Applications requiring operation below -40°C must use the original part. Applications within the -40°C to 125°C range are compatible with the substitute.

RoHS Compliance: The CM453232-681KL is ROHS3 compliant, while the 1812-684K is RoHS non-compliant. Applications subject to RoHS regulatory requirements must use the substitute part.

Physical Dimensions: The substitute part is longer (0.177" vs. 0.126") and lower profile (0.134" vs. 0.190"). PCB layout and clearance verification is required before substitution.

Packaging Format: The 1812-684K is supplied in Tape & Reel format, while the CM453232-681KL is available in Cut Tape & Digi-Reel format. Procurement and assembly processes may require adjustment.

Frequently Asked Questions (FAQ)

Q: Can the CM453232-681KL replace the 1812-684K in all applications?

A: No. The substitute part has a lower current rating (50 mA vs. 82 mA) and narrower operating temperature range (-40°C to 125°C vs. -55°C to 125°C). Substitution is valid only when application current requirements do not exceed 50 mA and operating temperature remains above -40°C.

Q: Are the physical dimensions compatible with the same PCB footprint?

A: Both parts use the 1812 package format and share the same width (0.126" / 3.20 mm). However, the substitute is longer (0.177" vs. 0.126") and lower profile (0.134" vs. 0.190"). PCB layout clearance must be verified before substitution.

Q: What is the difference between the 2-SMD and 1812 (4532 Metric) package designations?

A: Both designations refer to the same 1812 package footprint. The 2-SMD designation indicates a two-terminal surface mount device. The 1812 (4532 Metric) designation provides metric dimensions. These are equivalent package formats.

Q: Does the substitute part meet RoHS requirements?

A: Yes. The CM453232-681KL is ROHS3 compliant, while the 1812-684K is RoHS non-compliant. For applications requiring RoHS compliance, the substitute part is the appropriate selection.

Q: How do the Q factors compare between the two parts?

A: Both parts specify Q = 30, measured at slightly different frequencies (790 kHz for the original, 796 kHz for the substitute). This difference is within normal measurement tolerance and does not affect functional equivalence.

Q: What packaging options are available for each part?

A: The 1812-684K is supplied in Tape & Reel (TR) format. The CM453232-681KL is supplied in Cut Tape (CT) & Digi-Reel format. Procurement specifications must reflect the required packaging format.

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