PMH0805-400 Ferrite Bead Equivalent & Substitute Parts

Part Overview

The PMH0805-400 is a 40 Ohm ferrite bead in 0805 (2012 Metric) surface mount package manufactured by Bourns Inc. This component is designed for single-line EMI suppression applications with a maximum current rating of 2.5A and DC resistance of 30mOhm. The part is currently obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements.

Key Parameters

Parameter	Value
Impedance @ 100 MHz	40 Ohms
Current Rating (Max)	2.5A
DC Resistance (Max)	30mOhm
Package / Case	0805 (2012 Metric)
Mounting Type	Surface Mount
Operating Temperature	-55°C ~ 125°C
Number of Lines	1

Substitute Part Grouping Explanation

Substitution eligibility for the PMH0805-400 is determined by the following critical parameters:

Impedance @ 100 MHz: 40 Ohms (primary electrical specification)
Package / Case: 0805 (2012 Metric) (physical compatibility requirement)
Number of Lines: 1 (functional requirement)
Operating Temperature Range: -55°C ~ 125°C (environmental compatibility)
Mounting Type: Surface Mount (assembly compatibility)

Substitute parts must maintain the same impedance value and package footprint to ensure direct replacement capability. Current rating and DC resistance variations are acceptable provided the substitute meets or exceeds the original specifications for the intended application.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Impedance @ 100 MHz	Current Rating (Max)	DC Resistance (Max)	Package / Case	Operating Temperature	Product Status	RoHS Status
PMH0805-400	Bourns Inc.	40 Ohms	2.5A	30mOhm	0805 (2012 Metric)	-55°C ~ 125°C	Obsolete	RoHS non-compliant
MH2029-400Y	Bourns Inc.	40 Ohms	5A	20mOhm	0805 (2012 Metric)	-55°C ~ 125°C	Active	ROHS3 Compliant
HCB10-400-RC	Allied Components International	40 Ohms	3A	20mOhm	0805 (2012 Metric)	-55°C ~ 125°C	Active	RoHS Compliant
WLBD2012HCU400TH	Walsin Technology Corporation	40 Ohms	4A	30mOhm	0805 (2012 Metric)	-55°C ~ 125°C	Active	Not specified
742792012	Würth Elektronik	33 Ohms	4A	8mOhm	0805 (2012 Metric)	-55°C ~ 125°C	Active	ROHS3 Compliant
FBH201209T-470Y-S	Cal-Chip Electronics, Inc.	47 Ohms	3A	30mOhm	0805 (2012 Metric)	-55°C ~ 125°C	Active	RoHS Compliant
HCB10-390-RC	Allied Components International	39 Ohms	3A	20mOhm	0805 (2012 Metric)	-55°C ~ 125°C	Active	RoHS Compliant

Engineering Selection Recommendations

Direct Electrical Equivalents (40 Ohms @ 100 MHz):

MH2029-400Y and HCB10-400-RC are direct electrical equivalents with identical impedance specifications. MH2029-400Y offers superior performance with 5A current rating and 20mOhm DC resistance, and carries ROHS3 compliance. HCB10-400-RC provides RoHS compliance with 3A current rating and 20mOhm DC resistance. Both are active products suitable for new designs.

WLBD2012HCU400TH maintains the original 40 Ohm impedance and 30mOhm DC resistance profile with 4A current capability and active product status.

Near-Equivalent Options (±10% Impedance Tolerance):

HCB10-390-RC (39 Ohms) and FBH201209T-470Y-S (47 Ohms) provide impedance values within typical engineering tolerance bands. HCB10-390-RC offers improved DC resistance at 20mOhm. FBH201209T-470Y-S maintains the original 30mOhm DC resistance specification.

742792012 (33 Ohms) represents a greater impedance deviation and should be evaluated only when application requirements permit impedance variation beyond standard tolerance.

All substitute parts maintain the 0805 (2012 Metric) package footprint and surface mount compatibility. Selection should prioritize active product status and compliance certifications appropriate to the target application and regulatory environment.

Frequently Asked Questions (FAQ)

Q: Can MH2029-400Y directly replace PMH0805-400?

A: Yes. MH2029-400Y matches the critical electrical specification of 40 Ohms @ 100 MHz and maintains identical package geometry (0805 / 2012 Metric). The higher current rating (5A vs 2.5A) and lower DC resistance (20mOhm vs 30mOhm) represent performance improvements. MH2029-400Y is an active product with ROHS3 compliance.

Q: What is the difference between HCB10-400-RC and HCB10-390-RC?

A: Both parts are manufactured by Allied Components International in 0805 package with identical current ratings (3A) and DC resistance (20mOhm). HCB10-400-RC specifies 40 Ohms impedance, while HCB10-390-RC specifies 39 Ohms. Selection depends on whether the application requires exact 40 Ohm impedance or permits ±10% tolerance.

Q: Why does 742792012 have lower impedance (33 Ohms)?

A: 742792012 is a Würth Elektronik ferrite bead with different magnetic core composition, resulting in 33 Ohms @ 100 MHz. This represents approximately 18% impedance reduction from the original 40 Ohm specification. This part should be selected only when application circuit design permits impedance variation.

Q: Are all substitute parts RoHS compliant?

A: MH2029-400Y, HCB10-400-RC, HCB10-390-RC, and FBH201209T-470Y-S carry RoHS compliance certifications. 742792012 is ROHS3 compliant. WLBD2012HCU400TH RoHS status is not specified in available documentation. The original PMH0805-400 is RoHS non-compliant.

Q: Do all substitutes fit the same PCB footprint?

A: Yes. All listed substitute parts maintain the 0805 (2012 Metric) package specification with surface mount mounting type. Physical dimensions are equivalent, ensuring direct PCB footprint compatibility.

Q: Which substitute offers the best performance improvement?

A: MH2029-400Y provides the most significant performance enhancement with 5A current rating (vs 2.5A original) and 20mOhm DC resistance (vs 30mOhm original), while maintaining exact 40 Ohm impedance and active product status with ROHS3 compliance.

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