SC1212-681 Equivalent & Substitute Parts

Part Overview

The SC1212-681 is a 680 µH shielded inductor manufactured by Signal Transformer, rated for 175 mA maximum current with 9Ohm DC resistance. This component is classified as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications. The part operates across the industrial temperature range of -40°C to 125°C and meets ROHS3 compliance requirements.

Substiute Parts

SC1212-681

Signal TransformerIn Stock: 879SC1212-681 Datasheet

Current PartRFQ

1812R-684K

API Delevan Inc.In Stock: 7991812R-684K Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SC1212-681 is determined by the following critical electrical and mechanical parameters:

Electrical Criteria:

• Inductance value: 680 µH (primary matching criterion)
• Current rating: Substitute must support minimum 175 mA operation
• DC resistance: Substitute DCR must not exceed application thermal and efficiency limits
• Operating temperature range: Must cover -40°C ~ 125°C minimum

Mechanical Criteria:

• Mounting type: Surface Mount required
• Physical dimensions: Footprint compatibility within 4.60mm x 4.60mm constraint
• Height clearance: Maximum 2.30mm seated height

Compliance Criteria:

• RoHS3 compliance mandatory
• MSL rating of 1 acceptable

The 1812R-684K from API Delevan Inc. meets the core inductance specification of 680 µH and maintains surface mount compatibility. However, this substitute exhibits reduced current rating (82 mA versus 175 mA) and increased DC resistance (30Ohm versus 9Ohm), requiring circuit-level evaluation for thermal and performance impact.

Parameter Comparison

Engineering Selection Recommendations

The 1812R-684K qualifies as an electrical substitute based on matching inductance value and surface mount configuration. Both components maintain ROHS3 compliance and unlimited moisture sensitivity rating, satisfying regulatory requirements.

Selection of the 1812R-684K requires verification that circuit operating current does not exceed 82 mA, as the substitute is rated 47% lower than the original SC1212-681. The increased DC resistance of 30Ohm (versus 9Ohm) will generate proportionally higher I²R losses, affecting thermal performance and power efficiency.

The substitute's unshielded construction differs from the original shielded design. Applications requiring electromagnetic interference suppression must evaluate whether unshielded operation is acceptable for the target circuit environment.

Physical height difference (4.83mm versus 2.30mm) may impact PCB layout and component clearance constraints. The smaller footprint (3.20mm versus 4.60mm) provides marginal space advantage but does not offset the height increase.

Frequently Asked Questions (FAQ)

Q: Can the 1812R-684K directly replace the SC1212-681 in all applications?

A: No. The substitute is rated for 82 mA maximum current versus 175 mA for the original. Direct replacement is limited to circuits operating below 82 mA. Higher current applications require alternative solutions.

Q: What is the impact of increased DC resistance on circuit performance?

A: The 1812R-684K exhibits 30Ohm DCR compared to 9Ohm for the SC1212-681. At 82 mA operation, this generates 0.198W additional power dissipation versus 0.061W for the original, requiring thermal management evaluation.

Q: Does the unshielded construction of the 1812R-684K affect EMI performance?

A: Yes. The original SC1212-681 is shielded; the 1812R-684K is unshielded. Applications requiring electromagnetic shielding must assess whether unshielded operation introduces unacceptable coupling or noise into sensitive circuits.

Q: Are there physical mounting constraints with the 1812R-684K?

A: The substitute is 2.53mm taller (4.83mm versus 2.30mm seated height). PCB layout must accommodate this increased height. The smaller footprint (3.20mm versus 4.60mm) may provide minor routing benefits but does not compensate for height increase.

Q: Do both parts meet the same compliance standards?

A: Yes. Both SC1212-681 and 1812R-684K are ROHS3 compliant with MSL rating 1 (unlimited moisture sensitivity). Regulatory compliance is equivalent.

Q: What is the inductance tolerance difference between these parts?

A: The SC1212-681 has ±30% tolerance; the 1812R-684K has ±10% tolerance. The substitute provides tighter inductance accuracy, which may benefit frequency-dependent circuits.