SCR125B-821 Equivalent & Substitute Parts

Part Overview

The SCR125B-821 is a 820 µH shielded inductor manufactured by Signal Transformer, rated for 740 mA with a maximum DC resistance of 2Ohm. 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

SCR125B-821

Signal TransformerIn Stock: 965SCR125B-821 Datasheet

Current PartRFQ

7447709821

Würth ElektronikIn Stock: 17777447709821 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The Würth Elektronik part number 7447709821 qualifies as a substitute for the SCR125B-821 based on the following critical parameters:

• Identical inductance value: 820 µH with ±20% tolerance
• Identical inductance test frequency: 1 kHz
• Identical operating temperature range: -40°C to 125°C
• Identical shielding classification: Shielded
• Identical mounting type: Surface Mount
• Identical RoHS compliance: ROHS3 Compliant
• Identical moisture sensitivity level: MSL 1 (Unlimited)

The substitute part demonstrates superior electrical performance in current handling and DC resistance, making it suitable for direct replacement in applications where the SCR125B-821 is no longer available.

Parameter Comparison

Engineering Selection Recommendations

The Würth Elektronik 7447709821 is the designated substitute for the obsolete SCR125B-821. Selection is based on:

• Product status alignment: The substitute is active production status, ensuring long-term availability and supply chain stability
• Compliance certifications: Both parts maintain ROHS3 compliance and REACH unaffected status, meeting regulatory requirements
• Electrical parameter equivalence: Matching inductance, tolerance, operating temperature, and test frequency ensure functional compatibility
• Performance enhancement: The substitute provides improved current handling (950 mA vs 740 mA) and reduced DC resistance (1Ohm vs 2Ohm), offering superior performance margins in the same application space

Frequently Asked Questions (FAQ)

Q: Can the Würth Elektronik 7447709821 directly replace the Signal Transformer SCR125B-821?

A: Yes. Both parts share identical inductance (820 µH), tolerance (±20%), operating temperature range (-40°C to 125°C), shielding classification, and mounting type. The substitute meets all functional requirements for direct replacement.

Q: What are the key differences between these parts?

A: The substitute offers improved electrical performance with higher current rating (950 mA vs 740 mA), higher saturation current (1.1 A vs 360 mA), and lower DC resistance (1Ohm vs 2Ohm). These differences represent performance enhancements rather than incompatibilities.

Q: Are there packaging considerations for this substitution?

A: Both parts use nonstandard surface mount packages. Physical dimensions differ slightly: the SCR125B-821 measures 0.516" L x 0.476" W x 0.232" H, while the 7447709821 measures 0.472" L x 0.472" W x 0.394" H. PCB layout verification is required to confirm fit within available space.

Q: Do both parts meet the same compliance standards?

A: Yes. Both parts are ROHS3 compliant, REACH unaffected, and carry MSL 1 (Unlimited) moisture sensitivity ratings. Regulatory requirements are equivalent.

Q: Why is the SCR125B-821 marked as obsolete?

A: Obsolete status indicates the part is no longer in active production. The Würth Elektronik substitute ensures continued design support and component availability for applications currently using the Signal Transformer part.