Z0805C121ASMST Ferrite Bead 120 OHM 0805 Equivalent & Substitute Parts

Part Overview

The Z0805C121ASMST is a single-line ferrite bead manufactured by KEMET, designed for signal line filtering applications in 0805 (2012 Metric) surface mount packages. This component provides 120 Ohms impedance at 100 MHz with a maximum current rating of 800mA and operates across the temperature range of -55°C to 125°C.

The Z0805C121ASMST is classified as Obsolete. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs, repairs, and legacy system support. Multiple manufacturers produce functionally compatible ferrite beads that meet the same electrical and mechanical specifications.

Key Parameters

Parameter	Value
Impedance @ Frequency	120 Ohms @ 100 MHz
Current Rating (Max)	800mA
DC Resistance (DCR) (Max)	150mOhm
Package / Case	0805 (2012 Metric)
Number of Lines	1
Operating Temperature	-55°C ~ 125°C
Mounting Type	Surface Mount
Size / Dimension	0.079" L x 0.049" W (2.00mm x 1.25mm)
Height (Max)	0.041" (1.05mm)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the Z0805C121ASMST is determined by strict equivalence across the following critical parameters:

Mandatory Matching Parameters:

Impedance @ Frequency: 120 Ohms @ 100 MHz
Current Rating (Max): 800mA
Package / Case: 0805 (2012 Metric)
Number of Lines: 1
Operating Temperature Range: -55°C ~ 125°C
Mounting Type: Surface Mount
Physical Dimensions: 0.079" L x 0.049" W (2.00mm x 1.25mm)

Allowable Variation:

DC Resistance (DCR) (Max): Substitute parts may have DCR values of 100mOhm, 120mOhm, or 150mOhm. All values remain within acceptable operating parameters for signal line ferrite bead applications.
Height (Max): Substitute parts may have height specifications of 0.041" (1.05mm) or 0.043" (1.10mm), both compatible with standard 0805 PCB assembly processes.

All substitute parts listed are ROHS3 Compliant and have Moisture Sensitivity Level 1 (Unlimited), matching the environmental and regulatory compliance of the original part.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Impedance @ 100 MHz	Current Rating (Max)	DCR (Max)	Height (Max)	Product Status	Packaging
Z0805C121ASMST	KEMET	120 Ohms	800mA	150mOhm	0.041" (1.05mm)	Obsolete	Cut Tape (CT)
MMZ2012R121ATD25	TDK Corporation	120 Ohms	800mA	120mOhm	0.041" (1.05mm)	Last Time Buy	Cut Tape (CT)
ACML-0805-121-T	Abracon LLC	120 Ohms	800mA	150mOhm	0.041" (1.05mm)	Active	Tape & Reel (TR)
BBGK00201209121Y00	Pulse Electronics	120 Ohms	800mA	150mOhm	0.043" (1.10mm)	Active	Tape & Reel (TR)
BLM21AG121SN1D	Murata Electronics	120 Ohms	800mA	100mOhm	0.041" (1.05mm)	Active	Cut Tape (CT) & Digi-Reel®
FB201209T-121Y-S-1	Cal-Chip Electronics, Inc.	120 Ohms	800mA	150mOhm	0.043" (1.10mm)	Active	Tape & Reel (TR)
MMZ2012R121AT000	TDK Corporation	120 Ohms	800mA	120mOhm	0.041" (1.05mm)	Last Time Buy	Cut Tape (CT)
MMZ2012S121AT000	TDK Corporation	120 Ohms	800mA	150mOhm	0.041" (1.05mm)	Last Time Buy	Cut Tape (CT)
MMZ2012Y121BT000	TDK Corporation	120 Ohms	800mA	120mOhm	0.041" (1.05mm)	Last Time Buy	Cut Tape (CT)
WLBD2012K2U121TP	Walsin Technology Corporation	120 Ohms	800mA	150mOhm	0.043" (1.10mm)	Active	Tape & Reel (TR)

Engineering Selection Recommendations

Active Status Parts (Recommended for New Designs):

The following substitute parts carry Active product status and are recommended for new production designs and long-term availability:

ACML-0805-121-T (Abracon LLC): Matches DCR specification of 150mOhm and height of 0.041" (1.05mm). Available in Tape & Reel packaging with 4,692 units in stock.
BBGK00201209121Y00 (Pulse Electronics): Matches DCR specification of 150mOhm with height of 0.043" (1.10mm). Available in Tape & Reel packaging with 1,153 units in stock.
BLM21AG121SN1D (Murata Electronics): Provides superior DCR performance at 100mOhm (lower than original specification) with height of 0.041" (1.05mm). Available in Cut Tape and Digi-Reel packaging with 125,400 units in stock. This part offers the highest inventory availability.
FB201209T-121Y-S-1 (Cal-Chip Electronics, Inc.): Matches DCR specification of 150mOhm with height of 0.043" (1.10mm). Available in Tape & Reel packaging with 100,835 units in stock.
WLBD2012K2U121TP (Walsin Technology Corporation): Matches DCR specification of 150mOhm with height of 0.043" (1.10mm). Available in Tape & Reel packaging with 1,011 units in stock.

Last Time Buy Status Parts (Transition Required):

The following substitute parts carry Last Time Buy product status and are suitable for immediate replacement but require transition planning:

MMZ2012R121ATD25 (TDK Corporation): DCR of 120mOhm with height of 0.041" (1.05mm). Carries AEC-Q200 automotive qualification. Available in Cut Tape packaging with 4,300 units in stock.
MMZ2012R121AT000 (TDK Corporation): DCR of 120mOhm with height of 0.041" (1.05mm). Available in Cut Tape packaging with 17,300 units in stock.
MMZ2012S121AT000 (TDK Corporation): Matches DCR specification of 150mOhm with height of 0.041" (1.05mm). Available in Cut Tape packaging with 49,100 units in stock.
MMZ2012Y121BT000 (TDK Corporation): DCR of 120mOhm with height of 0.041" (1.05mm). Available in Cut Tape packaging with 81,864 units in stock.

Compliance and Certifications:

All substitute parts are ROHS3 Compliant and REACH Unaffected. The MMZ2012R121ATD25 carries AEC-Q200 automotive qualification, suitable for automotive and high-reliability applications. All parts maintain Moisture Sensitivity Level 1 (Unlimited), eliminating special storage and handling requirements.

Frequently Asked Questions (FAQ)

Q: Can I substitute the Z0805C121ASMST with any of the listed parts?

A: Yes. All listed substitute parts meet the mandatory electrical and mechanical parameters: 120 Ohms impedance at 100 MHz, 800mA current rating, 0805 (2012 Metric) package, single signal line configuration, and -55°C to 125°C operating temperature range. Physical dimensions and mounting type are identical across all parts.

Q: What is the difference between parts with 100mOhm, 120mOhm, and 150mOhm DCR specifications?

A: DC Resistance (DCR) represents the resistive component of the ferrite bead at DC and low frequencies. The Z0805C121ASMST specifies 150mOhm maximum. Substitute parts with lower DCR values (100mOhm or 120mOhm) provide improved performance characteristics with reduced power dissipation. All DCR values within this range are electrically compatible for signal line filtering applications.

Q: Are there packaging differences between substitute parts?

A: Yes. The original Z0805C121ASMST is supplied in Cut Tape (CT) packaging. Several substitute parts are available in Tape & Reel (TR) packaging, which is standard for high-volume production. Both packaging formats are compatible with automated assembly equipment. Cut Tape packaging is suitable for lower-volume applications and manual assembly.

Q: Which substitute part has the best inventory availability?

A: BLM21AG121SN1D (Murata Electronics) has the highest inventory with 125,400 units in stock. This part is available in both Cut Tape and Digi-Reel packaging formats and carries Active product status.

Q: What is the significance of "Last Time Buy" product status?

A: Last Time Buy status indicates that the manufacturer will discontinue production after a specified date. Parts with this status remain fully functional and compliant but require transition planning. TDK Corporation MMZ series parts (MMZ2012R121ATD25, MMZ2012R121AT000, MMZ2012S121AT000, MMZ2012Y121BT000) carry this status and should be evaluated for long-term design requirements.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts are ROHS3 Compliant. The original Z0805C121ASMST is also ROHS3 Compliant. All parts are REACH Unaffected, confirming compliance with European environmental regulations.

Q: Does height variation between 0.041" (1.05mm) and 0.043" (1.10mm) affect PCB assembly?

A: No. Both height specifications fall within standard 0805 component tolerances and are compatible with automated pick-and-place assembly equipment and standard reflow soldering processes. PCB design and assembly parameters do not require modification for either height specification.

Q: Which substitute part is recommended for automotive applications?

A: MMZ2012R121ATD25 (TDK Corporation) carries AEC-Q200 automotive qualification, making it suitable for automotive and high-reliability applications requiring automotive-grade component certification.

Q: Can I use substitute parts with lower DCR in existing designs without circuit modification?

A: Yes. Substitute parts with lower DCR values (such as BLM21AG121SN1D at 100mOhm) provide improved performance with reduced power dissipation and are direct electrical replacements. No circuit modifications are required.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message