Z0603C681CSMST Ferrite Bead Equivalent & Substitute Parts

Part Overview

The Z0603C681CSMST is a signal line ferrite bead manufactured by KEMET, rated at 680 Ohms impedance at 100 MHz in a 0603 (1608 Metric) surface mount package. This component is designed for electromagnetic interference (EMI) suppression in single-line signal applications with a maximum current rating of 150mA and 1 Ohm DC resistance.

The Z0603C681CSMST is classified as obsolete. Identifying equivalent and substitute ferrite beads ensures design continuity and maintains supply chain reliability for applications requiring this component's electrical and mechanical specifications.

Key Parameters

Parameter	Value
Impedance @ Frequency	680 Ohms @ 100 MHz
Current Rating (Max)	150mA
DC Resistance (DCR) (Max)	1 Ohm
Package / Case	0603 (1608 Metric)
Mounting Type	Surface Mount
Operating Temperature Range	-55°C ~ 125°C
Filter Type	Signal Line
Number of Lines	1
Height (Max)	0.037" (0.95mm)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Ferrite bead substitution is determined by electrical and mechanical compatibility within the following parameters:

Critical Substitution Parameters:

Package / Case: 0603 (1608 Metric) surface mount form factor
Mounting Type: Surface Mount
Number of Lines: 1 (single signal line)
Operating Temperature Range: -55°C ~ 125°C minimum
DC Resistance (DCR): 1 Ohm maximum
Impedance @ Frequency: Nominal impedance at 100 MHz
Current Rating: Must support application requirements
RoHS3 Compliance and MSL Level 1 rating

The substitute parts listed maintain the same 0603 package footprint and surface mount compatibility. Impedance values at 100 MHz range from 600 to 680 Ohms, representing parametric equivalence within ferrite bead performance bands. Current ratings of the substitutes (200mA to 250mA) exceed the original 150mA specification, providing design margin. All substitutes maintain identical DC resistance, operating temperature range, and regulatory compliance.

Parameter Comparison

Parameter	Z0603C681CSMST (KEMET)	BLM18HG601SN1D (Murata)	HZ1608U601TF (Sunlord)	PZ0603D601-R25TF (Sunlord)
Impedance @ Frequency	680 Ohms @ 100 MHz	600 Ohms @ 100 MHz	600 Ohms @ 100 MHz	600 Ohms @ 100 MHz
Current Rating (Max)	150mA	200mA	200mA	250mA
DC Resistance (DCR) (Max)	1 Ohm	1 Ohm	1 Ohm	1 Ohm
Package / Case	0603 (1608 Metric)	0603 (1608 Metric)	0603 (1608 Metric)	0201 (0603 Metric)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Height (Max)	0.037" (0.95mm)	0.037" (0.95mm)	0.037" (0.95mm)	0.037" (0.95mm)
Operating Temperature Range	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Not specified	Not specified
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Product Status	Obsolete	Active	Active	Active

Engineering Selection Recommendations

BLM18HG601SN1D (Murata Electronics) is the primary substitute for the Z0603C681CSMST. This part maintains identical package dimensions, mounting type, and operating temperature specifications. The 600 Ohms impedance at 100 MHz represents a 12% reduction from the original 680 Ohms specification, within typical ferrite bead performance tolerance bands. The 200mA current rating provides 33% additional capacity over the original 150mA specification. ROHS3 compliance and MSL Level 1 rating ensure regulatory and manufacturing process compatibility. Murata's EMIFIL® BLM18 series is an established active product line with consistent supply availability.

HZ1608U601TF (Shenzhen Sunlord Electronics) provides an alternative substitute with identical electrical parameters to the Murata part. The 600 Ohms impedance and 200mA current rating match the BLM18HG601SN1D specification. This part is available in Tape & Reel packaging and maintains the same 0603 footprint and height profile. Product status is active with documented inventory availability.

PZ0603D601-R25TF (Shenzhen Sunlord Electronics) is classified as a power line ferrite bead, distinct from the signal line filter type of the original part. While electrical parameters (600 Ohms impedance, 1 Ohm DCR, 250mA current rating) are compatible, the package designation (0201 / 0603 Metric) indicates a smaller physical footprint (0.024" L x 0.012" W versus 0.063" L x 0.031" W). This part is suitable only for applications where the reduced physical dimensions do not conflict with PCB layout constraints and where power line filtering characteristics are acceptable.

All three substitutes are active products with current manufacturing status, ensuring long-term supply chain viability compared to the obsolete original part.

Frequently Asked Questions (FAQ)

Q: Can the BLM18HG601SN1D replace the Z0603C681CSMST in my design?

A: Yes. Both parts share the 0603 (1608 Metric) surface mount package, identical mounting type, and matching operating temperature range (-55°C ~ 125°C). The 600 Ohms impedance at 100 MHz is within the parametric equivalence band for ferrite beads. The 200mA current rating exceeds the original 150mA specification. DC resistance remains at 1 Ohm maximum. Verify that your application tolerates the 80 Ohm impedance difference (680 Ohms to 600 Ohms) in EMI suppression performance.

Q: What is the impedance difference between the original part and the substitutes?

A: The Z0603C681CSMST is rated at 680 Ohms @ 100 MHz. All three substitute parts are rated at 600 Ohms @ 100 MHz, representing an 80 Ohm (approximately 12%) reduction. This difference falls within standard ferrite bead impedance tolerance bands and is typical when transitioning between manufacturers and product series.

Q: Are all substitutes RoHS3 compliant?

A: The BLM18HG601SN1D (Murata) explicitly states ROHS3 compliance. The HZ1608U601TF and PZ0603D601-R25TF (Sunlord) do not specify RoHS status in the provided data. Verify RoHS3 compliance with the manufacturer if regulatory certification is required for your application.

Q: What is the difference between the HZ1608U601TF and PZ0603D601-R25TF?

A: Both parts are manufactured by Shenzhen Sunlord Electronics and share 600 Ohms impedance and 1 Ohm DCR specifications. The HZ1608U601TF is classified as a signal line ferrite bead with 200mA current rating and standard 0603 dimensions (0.063" L x 0.031" W). The PZ0603D601-R25TF is a power line ferrite bead with 250mA current rating and reduced physical dimensions (0.024" L x 0.012" W). Select based on your application's filter type requirement and available PCB layout space.

Q: Can I use the PZ0603D601-R25TF as a direct footprint replacement?

A: No. While the PZ0603D601-R25TF maintains the same 0.037" (0.95mm) height, its length and width dimensions (0.024" L x 0.012" W) are significantly smaller than the original 0603 package (0.063" L x 0.031" W). This part requires PCB layout modification and is not a direct footprint replacement. Use only if your design can accommodate the smaller 0201 (0603 Metric) package dimensions.

Q: What is the current rating margin when using substitute parts?

A: The original Z0603C681CSMST is rated at 150mA. The BLM18HG601SN1D and HZ1608U601TF provide 200mA ratings (33% margin). The PZ0603D601-R25TF provides 250mA rating (67% margin). All substitutes support the original 150mA application requirement with additional design margin.

Q: Are there packaging differences between the substitutes?

A: Yes. The BLM18HG601SN1D is supplied in Cut Tape (CT) & Digi-Reel® packaging. The HZ1608U601TF and PZ0603D601-R25TF are supplied in Tape & Reel (TR) packaging. Verify packaging compatibility with your procurement and assembly processes.

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