SPD73-104M Equivalent & Substitute Parts

Part Overview

The SPD73-104M is a 100 µH shielded drum core wirewound inductor manufactured by API Delevan Inc., rated for 541 mA continuous current with a maximum DC resistance of 790 mOhm. This component is classified as obsolete, indicating discontinued production and limited availability for new designs. The part operates across the industrial temperature range of -55°C to 125°C and is mounted as a surface mount device in a nonstandard 7.30mm x 7.30mm package footprint.

Due to its obsolete status, identifying equivalent substitute parts is essential for design continuity, procurement reliability, and long-term supply chain management. Substitute components must maintain electrical performance within the specified inductance, current rating, and DC resistance parameters while meeting modern compliance and availability requirements.

Key Parameters

Parameter	Value	Unit	Criticality for Substitution
Inductance	100	µH	Critical
Inductance Tolerance	±20%	%	Critical
Current Rating (Continuous)	541	mA	Critical
DC Resistance (Maximum)	790	mOhm	Critical
Shielding	Shielded	—	Critical
Core Material	Ferrite	—	Critical
Mounting Type	Surface Mount	—	Critical
Package Footprint	7.30 x 7.30	mm	Critical
Operating Temperature Range	-55 to 125	°C	Important
Inductance Test Frequency	1	kHz	Important

Substitute Part Grouping Explanation

Substitute parts for the SPD73-104M are identified based on strict electrical and mechanical compatibility criteria. The following parameters determine valid substitution:

Electrical Parameters (Must Match or Exceed):

Inductance value: 100 µH at 1 kHz test frequency
Inductance tolerance: ±20% or tighter
Continuous current rating: minimum 541 mA
DC resistance: maximum 790 mOhm
Shielding: shielded construction required
Core material: ferrite

Mechanical Parameters (Must Match):

Mounting type: surface mount
Package footprint: 7.30mm x 7.30mm
Height compatibility: seated height must accommodate PCB assembly constraints

Compliance Parameters (Preferred):

Active product status for long-term availability
RoHS compliance for modern supply chains
AEC-Q200 certification for automotive-grade reliability

The SRR0745A-101M from Bourns Inc. qualifies as a direct substitute based on these criteria.

Parameter Comparison

Parameter	SPD73-104M (API Delevan)	SRR0745A-101M (Bourns)	Compatibility
Inductance	100 µH	100 µH	Match
Inductance Tolerance	±20%	±20%	Match
Current Rating	541 mA	700 mA	Substitute Exceeds
Current - Saturation	541 mA	780 mA	Substitute Exceeds
DC Resistance (Max)	790 mOhm	450 mOhm	Substitute Exceeds
Shielding	Shielded	Shielded	Match
Core Material	Ferrite	Ferrite	Match
Mounting Type	Surface Mount	Surface Mount	Match
Package Footprint	7.30 x 7.30 mm	7.30 x 7.30 mm	Match
Height - Seated (Max)	3.90 mm	4.70 mm	Substitute Taller
Operating Temperature	-55 to 125°C	-40 to 125°C	Substitute Range Narrower
Product Status	Obsolete	Active	Substitute Active
RoHS Status	Non-compliant	ROHS3 Compliant	Substitute Compliant
Certifications	None listed	AEC-Q200	Substitute Certified

Engineering Selection Recommendations

Primary Substitute: SRR0745A-101M (Bourns Inc.)

The SRR0745A-101M is the qualified substitute for the obsolete SPD73-104M based on the following engineering factors:

Electrical Compatibility: The substitute part meets all critical electrical requirements. The 700 mA continuous current rating and 780 mA saturation current exceed the original 541 mA specification, providing operational margin. The 450 mOhm maximum DC resistance is superior to the original 790 mOhm specification, resulting in lower power dissipation and improved thermal performance. Inductance value and tolerance remain identical at 100 µH ±20%.

Mechanical Compatibility: Both parts share identical package footprints (7.30mm x 7.30mm) and surface mount mounting type. The substitute part has a maximum seated height of 4.70mm compared to the original 3.90mm. This 0.80mm height difference must be evaluated against specific PCB assembly constraints and clearance requirements in the target application.

Compliance and Availability: The SRR0745A-101M holds active product status with 3300 pieces in stock, ensuring long-term procurement reliability. The part is ROHS3 compliant and carries AEC-Q200 certification, meeting modern regulatory and automotive-grade reliability standards. The original SPD73-104M is obsolete with no ongoing production.

Temperature Range Consideration: The substitute part operates across -40°C to 125°C, which is narrower than the original -55°C to 125°C range. Applications requiring operation below -40°C must evaluate this limitation against specific thermal requirements.

Frequently Asked Questions (FAQ)

Q: Can the SRR0745A-101M directly replace the SPD73-104M without circuit redesign?

A: The SRR0745A-101M is electrically compatible for applications operating above -40°C. The identical inductance value, matching tolerance, and superior current rating and DC resistance allow direct substitution in most circuits. However, the 0.80mm increase in seated height requires verification of PCB assembly clearance. Applications requiring operation below -40°C must evaluate the narrower temperature range.

Q: What is the significance of the lower DC resistance in the substitute part?

A: The SRR0745A-101M has a maximum DC resistance of 450 mOhm compared to the original 790 mOhm. Lower DC resistance reduces resistive losses and heat generation during operation. This is a performance improvement that benefits thermal management and efficiency, with no negative impact on circuit function.

Q: Does the higher current rating of the substitute part affect circuit operation?

A: No. The 700 mA continuous current rating of the SRR0745A-101M exceeds the original 541 mA specification. Higher current ratings provide operational margin and do not alter circuit behavior when the actual circuit current remains within design specifications.

Q: Is the 0.80mm height difference critical for PCB assembly?

A: The height difference must be evaluated against specific PCB design constraints. If the original design has clearance margins above the inductor, the additional 0.80mm may be accommodated without modification. If clearance is minimal, PCB layout adjustment or component repositioning may be required. Verify against your specific assembly drawing and clearance requirements.

Q: Why is RoHS compliance important for this substitution?

A: RoHS3 compliance ensures the substitute part meets current environmental and regulatory standards for electronic components. This is essential for products destined for markets with regulatory requirements and for long-term supply chain compatibility with modern manufacturing processes.

Q: What does AEC-Q200 certification indicate?

A: AEC-Q200 is an automotive-grade reliability standard. This certification indicates the SRR0745A-101M has undergone rigorous testing for automotive applications, including thermal cycling, vibration, and stress testing. This certification is valuable for applications requiring high reliability, though it is not required for non-automotive use.

Q: Can I use the SRR0745A-101M in applications requiring -55°C operation?

A: No. The SRR0745A-101M is rated for -40°C minimum operating temperature. Applications requiring operation at -55°C must either retain the original SPD73-104M (if available from inventory) or identify alternative parts with extended low-temperature ratings. Consult with the component supplier for extended temperature options.

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