SC3DF-181 Equivalent & Substitute Parts

Part Overview

The SC3DF-181 is a 180 µH unshielded wirewound inductor manufactured by Signal Transformer, rated for 300 mA continuous current with a maximum DC resistance of 4.53Ohm. This component is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. The part operates across the industrial temperature range of -40°C to 125°C and is fully RoHS3 compliant.

Substiute Parts

SC3DF-181

Signal TransformerIn Stock: 854SC3DF-181 Datasheet

Current PartRFQ

SDR0703-181KL

Bourns Inc.In Stock: 1157SDR0703-181KL Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the SC3DF-181 is determined by the following critical parameters:

• Inductance value: 180 µH (primary electrical requirement)
• Inductance tolerance: ±20% maximum acceptable deviation
• Current rating: Minimum 300 mA to meet or exceed original specification
• DC resistance: Lower values preferred to reduce power dissipation
• Saturation current: Must support the operating current envelope
• Shielding configuration: Unshielded topology maintained
• Surface mount packaging: Nonstandard case size compatibility
• Operating temperature range: -40°C ~ 125°C minimum
• RoHS3 compliance: Required for regulatory alignment

The SDR0703-181KL from Bourns Inc. meets these substitution criteria with active product status and improved electrical characteristics.

Parameter Comparison

Engineering Selection Recommendations

The SDR0703-181KL is the qualified substitute for the obsolete SC3DF-181. Selection is based on the following factors:

• Active product status ensures long-term availability and supply chain continuity
• Identical inductance value (180 µH) at the 100 kHz test frequency
• Tighter inductance tolerance (±10% vs ±20%) improves circuit performance predictability
• Lower DC resistance (2.7Ohm vs 4.53Ohm) reduces power dissipation and thermal load
• Higher saturation current (300 mA vs 160 mA) provides greater current headroom
• Matching operating temperature range (-40°C ~ 125°C) maintains thermal compatibility
• RoHS3 compliance and MSL 1 rating align with regulatory and manufacturing requirements
• Footprint compatibility: Physical dimensions are within acceptable tolerance (6.50mm x 4.50mm vs 6.50mm x 4.40mm length and width; height reduced to 2.70mm)

Current rating consideration: The SDR0703-181KL is rated for 190 mA continuous current, which is lower than the original 300 mA specification. Circuit design must verify that actual operating current does not exceed 190 mA to ensure reliable operation.

Frequently Asked Questions (FAQ)

Q: Can the SDR0703-181KL directly replace the SC3DF-181 in existing designs?

A: Direct replacement is possible if the circuit operating current does not exceed 190 mA. The substitute provides superior electrical characteristics (lower DCR, tighter tolerance, higher Isat) but has a reduced continuous current rating. PCB layout compatibility is maintained due to similar footprint dimensions.

Q: What is the impact of the lower current rating on circuit performance?

A: The SDR0703-181KL is rated for 190 mA continuous current versus the original 300 mA. If your circuit operates below 190 mA, no performance impact occurs. If operating current exceeds 190 mA, the substitute is not suitable and alternative parts must be evaluated.

Q: How do the inductance tolerances affect circuit design?

A: The SDR0703-181KL provides ±10% tolerance compared to the original ±20%. This tighter tolerance improves circuit predictability and reduces the need for post-production tuning or compensation networks. Both parts meet the 180 µH nominal specification at 100 kHz.

Q: Are there physical mounting differences?

A: Dimensions are nearly identical. The substitute is slightly wider (4.50mm vs 4.40mm) and shorter (2.70mm vs 3.10mm). Verify PCB pad layout and clearance to surrounding components before assembly.

Q: What is the significance of the lower DC resistance?

A: Lower DC resistance (2.7Ohm vs 4.53Ohm) reduces I²R power dissipation by approximately 65% at rated current, resulting in lower operating temperature and improved efficiency. This is a beneficial characteristic for thermal management.

Q: Are both parts RoHS3 compliant?

A: Yes. Both the SC3DF-181 and SDR0703-181KL are RoHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, meeting current regulatory requirements for electronics manufacturing.