SPD125R-684M Equivalent & Substitute Parts

Part Overview

The SPD125R-684M is a 680 µH shielded drum core wirewound inductor manufactured by API Delevan Inc., designed for surface mount applications with a 500 mA current rating and 1.3Ohm maximum DC resistance. This component operates across the temperature range of -55°C to 125°C and is classified as Active product status with ROHS3 compliance.

Substitute parts become necessary when the primary component experiences supply constraints, extended lead times, or when design requirements permit operation within alternative electrical and mechanical specifications. The substitute identified maintains the core inductance value while presenting variations in current rating, DC resistance, and physical dimensions that must be evaluated for application compatibility.

Key Parameters

Parameter	SPD125R-684M
Inductance	680 µH
Current Rating	500 mA
DC Resistance (Max)	1.3Ohm
Saturation Current	500 mA
Core Material	Ferrite
Shielding	Shielded
Mounting Type	Surface Mount
Operating Temperature	-55°C to 125°C
Package Type	Nonstandard
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the SPD125R-684M is determined by the following critical parameters:

Primary Matching Criteria:

Inductance value: 680 µH (exact match required)
Core type: Ferrite drum core, shielded configuration
Mounting technology: Surface mount
Regulatory compliance: ROHS3 Compliant

Secondary Compatibility Parameters:

Current rating tolerance: Substitute must support minimum 400 mA continuous operation
DC resistance: Substitute DCR must not exceed 1.5Ohm maximum
Operating temperature range: Minimum -40°C to 125°C
Physical form factor: Nonstandard package, drum core geometry

The substitute SRR1206-681KL from Bourns Inc. satisfies all primary matching criteria and operates within acceptable secondary parameter boundaries, though with reduced current rating (400 mA versus 500 mA) and increased DC resistance (1.5Ohm versus 1.3Ohm maximum).

Parameter Comparison

Parameter	SPD125R-684M (API Delevan)	SRR1206-681KL (Bourns)	Variance
Inductance	680 µH	680 µH	Match
Inductance Tolerance	±20%	±10%	Substitute tighter
Current Rating	500 mA	400 mA	Substitute -100 mA
Saturation Current	500 mA	700 mA	Substitute higher
DC Resistance (Max)	1.3Ohm	1.5Ohm	Substitute +0.2Ohm
Core Material	Ferrite	Ferrite	Match
Shielding	Shielded	Shielded	Match
Operating Temperature	-55°C to 125°C	-40°C to 125°C	Substitute narrower low end
Mounting Type	Surface Mount	Surface Mount	Match
Package Type	Nonstandard	Nonstandard	Match
Size (L x W)	12.00mm x 12.00mm	12.70mm x 12.70mm	Substitute +0.70mm
Height (Max)	6.00mm	6.50mm	Substitute +0.50mm
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Match
MSL Rating	1 (Unlimited)	1 (Unlimited)	Match

Engineering Selection Recommendations

Primary Component (SPD125R-684M): The SPD125R-684M remains the preferred selection when application requirements demand 500 mA continuous current operation, extended low-temperature operation to -55°C, or when the lower DC resistance of 1.3Ohm maximum is critical for power dissipation budgets. This component is Active status with full ROHS3 and REACH compliance.

Substitute Component (SRR1206-681KL): The SRR1206-681KL from Bourns Inc. is suitable for applications where continuous current requirements do not exceed 400 mA and minimum operating temperature does not fall below -40°C. The substitute offers tighter inductance tolerance (±10% versus ±20%) and higher saturation current (700 mA). The increased physical dimensions (12.70mm x 12.70mm footprint, 6.50mm height) and elevated DC resistance (1.5Ohm maximum) must be verified against PCB layout constraints and thermal management requirements.

Both components maintain Active product status and full regulatory compliance (ROHS3, REACH Unaffected, EAR99 classification).

Frequently Asked Questions (FAQ)

Q: Can SRR1206-681KL replace SPD125R-684M in all applications?

A: No. The substitute is limited to applications where continuous current does not exceed 400 mA. If your circuit requires the full 500 mA rating of the original component, substitution is not permissible. Verify actual circuit current draw before proceeding with substitution.

Q: What is the impact of increased DC resistance in the substitute?

A: The SRR1206-681KL exhibits 1.5Ohm maximum DC resistance compared to 1.3Ohm maximum in the SPD125R-684M. This 0.2Ohm increase results in higher power dissipation at rated current. Calculate power loss using P = I²R to determine if thermal performance remains acceptable in your application.

Q: Are there physical compatibility issues with the substitute?

A: Yes. The SRR1206-681KL is larger: 12.70mm x 12.70mm footprint (versus 12.00mm x 12.00mm) and 6.50mm height (versus 6.00mm). Verify PCB layout clearances and component spacing before substitution. The nonstandard package geometry requires manual verification against your specific board design.

Q: Does the substitute operate at lower temperatures?

A: The SRR1206-681KL operates from -40°C to 125°C, compared to -55°C to 125°C for the SPD125R-684M. If your application requires operation below -40°C, the substitute is not suitable.

Q: What is the advantage of the substitute's tighter inductance tolerance?

A: The SRR1206-681KL provides ±10% inductance tolerance versus ±20% for the original component. This tighter tolerance may benefit applications with strict inductance specifications, though both components meet the 680 µH nominal value.

Q: Are both components RoHS compliant?

A: Yes. Both SPD125R-684M and SRR1206-681KL are ROHS3 Compliant with MSL rating of 1 (Unlimited) and REACH Unaffected status, suitable for regulated manufacturing environments.

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