SCH74-270 Equivalent & Substitute Parts

Part Overview

The SCH74-270 is a 27 µH unshielded wirewound inductor manufactured by Signal Transformer, rated for 2 A continuous current with a maximum DC resistance of 160 mOhm. 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

SCH74-270

Signal TransformerIn Stock: 895SCH74-270 Datasheet

Current PartRFQ

SPD74R-273M

API Delevan Inc.In Stock: 898SPD74R-273M Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SCH74-270 is determined by the following critical parameters:

• Inductance Value: 27 µH nominal (tolerance range acceptable within design margins)
• Current Rating: Minimum 1.7 A to support the original 2 A specification
• DC Resistance: Maximum 160 mOhm to maintain circuit performance
• Mounting Type: Surface Mount required for PCB compatibility
• Operating Temperature: Minimum -40°C to 125°C range
• Compliance: ROHS3 and REACH compliance maintained

The SPD74R-273M from API Delevan Inc. meets these substitution criteria with equivalent inductance, compatible current handling, and superior DC resistance characteristics. The substitute part is active in production status, ensuring long-term availability.

Parameter Comparison

Engineering Selection Recommendations

The SPD74R-273M is the qualified substitute for the obsolete SCH74-270 based on the following factors:

• Inductance Match: Both parts specify 27 µH at 1 kHz test frequency, ensuring functional equivalence in circuit operation.
• Current Handling: The substitute's 1.7 A rating is within acceptable operating margins for applications originally designed for 2 A, provided circuit current does not exceed 1.7 A continuous.
• DC Resistance Improvement: The SPD74R-273M offers superior DC resistance at 150 mOhm maximum, compared to 160 mOhm, reducing resistive losses.
• Compliance Continuity: Both parts maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory requirements are met.
• Production Availability: The substitute part is active in production with confirmed inventory, eliminating obsolescence risk.
• Temperature Range Extension: The substitute supports -55°C to 125°C operation, providing expanded low-temperature capability.

Frequently Asked Questions (FAQ)

Q: Can the SPD74R-273M directly replace the SCH74-270 in all applications?

A: Direct substitution is valid when circuit current requirements do not exceed 1.7 A continuous. The 27 µH inductance value and superior DC resistance ensure functional compatibility. Applications requiring the full 2 A rating must be evaluated for current margin reduction.

Q: What is the impact of the shielding difference between the two parts?

A: The SCH74-270 is unshielded while the SPD74R-273M is shielded. Shielding reduces electromagnetic interference emission and susceptibility. In applications sensitive to EMI, the shielded substitute may provide improved performance. In noise-critical environments, shielding is beneficial.

Q: How does the inductance tolerance difference affect circuit performance?

A: The SCH74-270 specifies ±10% tolerance while the SPD74R-273M specifies ±20%. For circuits with tight inductance requirements, the wider tolerance of the substitute must be evaluated against design specifications. Both parts are tested at 1 kHz.

Q: Are there physical dimension considerations for PCB layout?

A: The SCH74-270 measures 0.315" L × 0.287" W × 0.205" H (8.00mm × 7.30mm × 5.20mm). The SPD74R-273M measures 0.287" L × 0.287" W × 0.185" H (7.30mm × 7.30mm × 4.70mm). The substitute is slightly smaller, allowing direct footprint compatibility with potential layout optimization.

Q: What is the packaging format of the substitute part?

A: The SPD74R-273M is supplied in Tape & Reel (TR) format, standard for automated assembly. The original SCH74-270 packaging format is listed as nonstandard. Tape & Reel packaging is compatible with standard pick-and-place equipment.