SCH74-271 Equivalent & Substitute Parts

Part Overview

The SCH74-271 is a 270 µH unshielded wirewound surface mount inductor manufactured by Signal Transformer, rated for 500 mA continuous current with a maximum DC resistance of 1.38Ohm. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing design support and production continuity. The part operates across the industrial temperature range of -40°C to 125°C and meets ROHS3 compliance requirements.

Substiute Parts

SCH74-271

Signal TransformerIn Stock: 1189SCH74-271 Datasheet

Current PartRFQ

SPD74R-274M

API Delevan Inc.In Stock: 718SPD74R-274M Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SCH74-271 is determined by the following critical parameters:

• Inductance Value: Must be 270 µH at 1 kHz test frequency
• Current Rating: Minimum 500 mA continuous current capability
• DC Resistance: Maximum 1.38Ohm to maintain circuit performance
• Mounting Type: Surface mount configuration required
• Physical Footprint: Compatible with 8.00mm x 7.30mm maximum lateral dimensions and 5.20mm maximum height
• Operating Temperature Range: Must support -40°C to 125°C minimum
• Compliance: ROHS3 compliance required

The SPD74R-274M from API Delevan Inc. meets these substitution criteria with equivalent inductance, superior current rating (530 mA), and compatible surface mount packaging, though with modified shielding characteristics and increased DC resistance tolerance.

Parameter Comparison

Engineering Selection Recommendations

The SPD74R-274M is the manufacturer-recommended substitute for the obsolete SCH74-271. Both components maintain ROHS3 compliance and unlimited moisture sensitivity rating, ensuring regulatory and environmental compatibility. The substitute part offers improved current saturation performance (530 mA versus 480 mA) and an extended lower operating temperature limit (-55°C versus -40°C), providing enhanced thermal margin for demanding applications.

The SPD74R-274M features shielded construction compared to the unshielded original, which may provide electromagnetic interference reduction benefits in sensitive circuit environments. The active product status of the substitute ensures long-term availability and supply chain continuity. Physical dimensions are compatible with the original footprint, with the substitute occupying slightly less board space (7.30mm x 7.30mm versus 8.00mm x 7.30mm) and lower profile (4.70mm versus 5.20mm).

The increased DC resistance tolerance (±20% versus ±10%) and slightly higher maximum DCR (1.64Ohm versus 1.38Ohm) require circuit-level verification to confirm acceptable performance in applications with tight impedance specifications.

Frequently Asked Questions (FAQ)

Q: Can the SPD74R-274M directly replace the SCH74-271 in all applications?

A: The SPD74R-274M meets the core substitution criteria of 270 µH inductance, surface mount configuration, and compatible physical footprint. However, the increased DC resistance (1.64Ohm maximum versus 1.38Ohm maximum) and wider inductance tolerance (±20% versus ±10%) require circuit validation. Applications with strict impedance or power loss budgets must confirm acceptable performance margins.

Q: What is the significance of shielding differences between these parts?

A: The SCH74-271 is unshielded, while the SPD74R-274M features shielded drum core construction. Shielding reduces electromagnetic field radiation and susceptibility to external interference. In applications where EMI performance is critical, the shielded substitute may provide improved circuit stability. In applications where unshielded operation is specifically required, this difference must be evaluated.

Q: Are there packaging differences that affect assembly?

A: Both parts are surface mount components with compatible footprints. The SPD74R-274M is supplied in Tape & Reel (TR) packaging, while the original part number does not specify packaging format. Both maintain MSL 1 (Unlimited) moisture sensitivity, eliminating special storage or handling requirements.

Q: How do the current ratings compare?

A: The SPD74R-274M provides 530 mA continuous current rating and 530 mA saturation current, compared to the SCH74-271 at 500 mA continuous and 480 mA saturation. The substitute offers 6% higher continuous current capacity and 10% higher saturation current, providing additional thermal and magnetic headroom for the same inductance value.

Q: What compliance certifications apply to both parts?

A: Both the SCH74-271 and SPD74R-274M are ROHS3 compliant and REACH unaffected, meeting current environmental and hazardous substance regulations. Both maintain MSL 1 (Unlimited) moisture sensitivity classification.