Ferrite Bead 40 OHM 0805 1LN (74279208)

Part Overview

The Würth Elektronik 74279208 is a single-line ferrite bead in 0805 (2012 Metric) surface mount package rated for 40 Ohms impedance at 100 MHz with 500mA maximum current and 150mOhm DC resistance. This part is classified as obsolete. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs and field replacements.

Key Parameters

Parameter	Value
Manufacturer Part Number	74279208
Manufacturer	Würth Elektronik
Series	WE-CBF
Package / Case	0805 (2012 Metric)
Impedance @ Frequency	40 Ohms @ 100 MHz
Current Rating (Max)	500mA
DC Resistance (DCR) (Max)	150mOhm
Operating Temperature	-55°C ~ 125°C
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 74279208 is determined by the following critical parameters:

Package / Case: 0805 (2012 Metric) surface mount form factor
Impedance @ Frequency: 40 Ohms @ 100 MHz (primary electrical specification)
Operating Temperature Range: -55°C ~ 125°C
Number of Lines: 1 (single signal line)
RoHS Compliance: ROHS3 Compliant

Substitute parts are grouped into two categories:

Direct Impedance Match (40 Ohms @ 100 MHz): Parts with identical impedance specification, allowing direct replacement without circuit redesign.

Parametric Equivalent (32-33 Ohms @ 100 MHz): Parts with impedance within acceptable tolerance range for signal line ferrite bead applications, maintaining functional compatibility within the same package footprint.

Parameter Comparison

Part Number	Manufacturer	Impedance @ 100 MHz	Current Rating (Max)	DCR (Max)	Package	Product Status	RoHS Status
74279208	Würth Elektronik	40 Ohms	500mA	150mOhm	0805 (2012 Metric)	Obsolete	ROHS3 Compliant
742792012	Würth Elektronik	33 Ohms	4A	8mOhm	0805 (2012 Metric)	Active	ROHS3 Compliant
74279201	Würth Elektronik	32 Ohms	500mA	150mOhm	0805 (2012 Metric)	Active	ROHS3 Compliant
EMI0805R-40	API Delevan Inc.	40 Ohms	600mA	50mOhm	0805 (2012 Metric)	Active	ROHS3 Compliant
FB201209T-400Y-S	Cal-Chip Electronics, Inc.	40 Ohms	800mA	50mOhm	0805 (2012 Metric)	Active	RoHS Compliant
ILBB0805ER320V	Vishay Dale	32 Ohms	600mA	60mOhm	0805 (2012 Metric)	Active	ROHS3 Compliant
WLBD2012K2U400TP	Walsin Technology Corporation	40 Ohms	800mA	50mOhm	0805 (2012 Metric)	Active	ROHS3 Compliant

Engineering Selection Recommendations

All listed substitute parts maintain the 0805 (2012 Metric) surface mount package and operating temperature range of -55°C to 125°C, ensuring mechanical and thermal compatibility with the original 74279208 design.

For direct replacement requiring identical 40 Ohms impedance specification, the following active parts are available: EMI0805R-40 (API Delevan Inc.), FB201209T-400Y-S (Cal-Chip Electronics, Inc.), and WLBD2012K2U400TP (Walsin Technology Corporation). All three maintain ROHS3 compliance and provide improved current ratings (600mA to 800mA) compared to the original 500mA specification.

For applications where impedance tolerance permits 32-33 Ohms operation, Würth Elektronik offers two active alternatives within their WE-CBF series: 742792012 (33 Ohms, 4A rating) and 74279201 (32 Ohms, 500mA rating). The Vishay Dale ILBB0805ER320V (32 Ohms) provides an alternative from a different manufacturer with 600mA current rating.

All substitute parts listed maintain ROHS3 compliance or equivalent RoHS certification status, ensuring regulatory alignment with the original component specification.

Frequently Asked Questions (FAQ)

Q: Can I use a 32-33 Ohm ferrite bead as a direct replacement for the 40 Ohm 74279208?

A: Yes, within signal line ferrite bead applications. The 32-33 Ohm impedance range represents a parametric equivalent suitable for the same package footprint and operating conditions. Circuit performance impact depends on the specific EMI filtering requirements of your application.

Q: What is the difference between the 742792012 and 74279201 substitutes?

A: Both are Würth Elektronik WE-CBF series parts in 0805 package with similar impedance (33 Ohms and 32 Ohms respectively). The 742792012 offers significantly higher current rating (4A versus 500mA) and lower DC resistance (8mOhm versus 150mOhm), making it suitable for higher-current applications. The 74279201 maintains the original 500mA current specification with identical 150mOhm DCR.

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

A: No. The original 74279208 is supplied in Tape & Reel (TR) format. The 742792012 is available in Cut Tape (CT) & Digi-Reel® format. Other substitutes are available in Tape & Reel (TR) format. Packaging format selection depends on your procurement and assembly requirements.

Q: Do all substitute parts meet the same compliance standards as the original?

A: All listed substitutes maintain ROHS3 compliance or equivalent RoHS certification. All parts are REACH Unaffected and classified under ECCN EAR99, matching the regulatory profile of the original 74279208.

Q: Which substitute offers the best performance improvement over the original 74279208?

A: The FB201209T-400Y-S and WLBD2012K2U400TP both provide identical 40 Ohms impedance with improved current ratings (800mA) and significantly lower DC resistance (50mOhm versus 150mOhm), resulting in reduced insertion loss and heat generation in signal line applications.

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