SPD73-333M 33µH Shielded Drum Core Wirewound Inductor

Part Overview

The SPD73-333M is a 33 µH shielded drum core wirewound inductor manufactured by API Delevan Inc., rated for 981 mA continuous current with a maximum DC resistance of 240 mOhm. This component operates across an industrial temperature range of -55°C to 125°C and is designed for surface mount applications with nonstandard packaging. The product is currently classified as obsolete, necessitating identification of equivalent alternatives for ongoing procurement and design continuity.

Substiute Parts

SPD73-333M

API Delevan Inc.In Stock: 749SPD73-333M Datasheet

Current PartRFQ

CDRH73NP-330MC-B

Sumida America Components Inc.In Stock: 977CDRH73NP-330MC-B Datasheet

SimilarRFQ

SRR0745A-330M

Bourns Inc.In Stock: 950405SRR0745A-330M Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SPD73-333M is determined by strict electrical and mechanical compatibility criteria. All candidate parts must meet the following core requirements: identical inductance value of 33 µH, identical inductance tolerance of ±20%, ferrite core material with shielding, surface mount configuration, and compatible footprint dimensions (7.30 mm × 7.30 mm).

The current rating tolerance is established as the primary variable parameter. Substitute parts must maintain a minimum continuous current rating of 981 mA to support the original design's operational envelope. Parts with lower current ratings (such as 910 mA) are unsuitable for direct substitution in current-critical applications.

The maximum DC resistance of 240 mOhm establishes the upper acceptable limit. Substitute parts with lower DC resistance (such as 150 mOhm) provide improved performance characteristics and are electrically compatible.

The operating temperature range may be restricted in certain substitute parts. Designs requiring the full -55°C to 125°C range must select substitutes supporting this specification; however, substitutes with -40°C to 100°C or -40°C to 125°C ratings are suitable for applications operating within those respective ranges.

Parameter Comparison

Engineering Selection Recommendations

SRR0745A-330M (Bourns Inc.) is the primary recommended substitute. This part is in active production status, meets all core electrical parameters with superior current rating (1.35 A versus 981 mA) and reduced DC resistance (150 mOhm versus 240 mOhm), and maintains the full -40°C to 125°C operating temperature range. The component carries AEC-Q200 automotive qualification and ROHS3 compliance, supporting modern regulatory requirements. Height is 4.70 mm, which exceeds the original 3.90 mm; design validation is required to confirm PCB layout compatibility. The part is available in high-volume inventory (950,300 units) and supports both cut tape and digi-reel packaging options.

CDRH73NP-330MC-B (Sumida America Components Inc.) is a secondary substitute suitable for applications where current requirements do not exceed 910 mA. This part maintains the original 240 mOhm DC resistance specification and operates within -40°C to 100°C. Height is 3.40 mm, providing better spatial constraints than the original. The component is ROHS3 compliant and available in tape and reel packaging. This option is constrained by lower current rating and reduced upper temperature limit (-40°C versus -55°C lower bound unavailable).

Designs requiring the full -55°C to 125°C operating window must use the Bourns SRR0745A-330M. Designs limited to -40°C to 100°C operation may use either substitute. Current-sensitive applications require confirmation that system operating current does not exceed component ratings.

Frequently Asked Questions (FAQ)

Q: Can CDRH73NP-330MC-B replace SPD73-333M in all applications? A: No. The CDRH73NP-330MC-B has a maximum continuous current rating of 910 mA, which is below the SPD73-333M specification of 981 mA. This part is suitable only for applications where actual circuit current does not exceed 910 mA. Additionally, the operating temperature range is limited to -40°C to 100°C, restricting use in applications requiring the original -55°C lower bound.

Q: Why does SRR0745A-330M have lower DC resistance than the original part? A: Lower DC resistance (150 mOhm versus 240 mOhm) represents an improved design characteristic. The Bourns SRR0745A-330M delivers superior electrical performance while maintaining identical inductance and tolerance specifications. Lower resistance reduces power dissipation and heat generation in the inductor during operation.

Q: Are there physical height constraints with substitute parts? A: Yes. SRR0745A-330M has a seated height of 4.70 mm compared to 3.90 mm for the original SPD73-333M; CDRH73NP-330MC-B measures 3.40 mm. PCB clearance and component placement must be validated during design integration, particularly where board height is constrained.

Q: What does AEC-Q200 qualification on the Bourns part mean? A: AEC-Q200 is an automotive electronics qualification standard. This certification indicates the component has been validated for automotive-grade reliability and performance. For non-automotive applications, this represents an additional assurance of manufacturing quality.

Q: Can I use SRR0745A-330M in designs requiring operation below -40°C? A: No. The SRR0745A-330M specifies -40°C as the lower operating limit. For applications requiring operation at -55°C, no suitable active substitute currently exists from the provided candidate parts. Legacy stock of the original SPD73-333M would be required or alternative inductance solutions must be evaluated.

Q: What is the difference between "Current Rating" and "Current – Saturation" specifications? A: Current Rating represents the continuous current the inductor can carry under normal operating conditions. Current – Saturation (Isat) indicates the current level at which the inductor's inductance begins to decrease due to core saturation. Not all datasheets provide saturation current; when available, it is typically higher than the continuous rating.