74F685AI-RC Equivalent & Substitute Parts

Part Overview

The 74F685AI-RC is a 68 µH unshielded drum core wirewound inductor manufactured by Bourns Inc., rated for 250 mA with a maximum DC resistance of 4 Ohm. This through-hole axial component operates across a temperature range of -55°C to 105°C and is compliant with ROHS3 and REACH standards. The product is currently obsolete, making equivalent substitutes necessary for ongoing design requirements and production continuity.

Substiute Parts

74F685AI-RC

Bourns Inc.In Stock: 80274F685AI-RC Datasheet

Current PartRFQ

1945R-18J

API Delevan Inc.In Stock: 10281945R-18J Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 74F685AI-RC is determined by the following critical parameters:

• Inductance value: 68 µH (exact match required)
• Current rating: 250 mA minimum
• Mounting type: Through hole axial configuration
• Shielding: Unshielded
• DC resistance: Within acceptable circuit tolerance
• Operating temperature range: Must support -55°C minimum
• Compliance: ROHS3 and REACH standards

The 1945R-18J from API Delevan Inc. meets all substitution criteria. While it features a molded construction versus drum core and has a slightly higher DCR of 4.48 Ohm, these differences remain within acceptable electrical parameters for equivalent circuit performance at the specified current and frequency ratings.

Parameter Comparison

Engineering Selection Recommendations

The 1945R-18J serves as a direct functional equivalent to the obsolete 74F685AI-RC. Both components maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory continuity in production environments. The substitute part offers an extended operating temperature range to 125°C, providing additional thermal margin beyond the original specification.

The 1945R-18J features improved inductance tolerance (±5% versus ±10%), which may benefit circuit performance in applications requiring tighter value control. The DCR increase of 0.48 Ohm represents a 12% rise from the original specification and should be evaluated within the context of circuit power dissipation and impedance requirements.

Both components are through-hole axial inductors with identical current ratings and unshielded construction, ensuring mechanical and electrical compatibility in PCB layouts designed for the 74F685AI-RC.

Frequently Asked Questions (FAQ)

Q: Can the 1945R-18J replace the 74F685AI-RC in existing designs?

A: Yes. Both components share identical inductance values (68 µH), current ratings (250 mA), mounting types (through-hole axial), and shielding characteristics (unshielded). The substitute maintains regulatory compliance with ROHS3 and REACH standards.

Q: What is the impact of the higher DC resistance in the 1945R-18J?

A: The 1945R-18J has a DCR of 4.48 Ohm compared to 4 Ohm maximum in the 74F685AI-RC. This 0.48 Ohm difference increases power dissipation proportionally with circuit current. Verify that circuit thermal design accommodates this additional loss.

Q: Are there physical dimension differences between these parts?

A: Yes. The 74F685AI-RC measures 0.200" diameter × 0.500" length (5.08mm × 12.70mm), while the 1945R-18J measures 0.193" diameter × 0.447" length (4.90mm × 11.35mm). The substitute is slightly smaller and may require PCB layout verification for through-hole spacing and component clearance.

Q: What is the difference between drum core and molded construction?

A: The 74F685AI-RC uses drum core construction; the 1945R-18J uses molded construction. Both are unshielded wirewound inductors. Molded construction typically provides improved mechanical robustness and environmental protection, while drum core designs may offer different frequency response characteristics.

Q: Does the 1945R-18J support the full operating temperature range of the 74F685AI-RC?

A: Yes. The 1945R-18J operates from -55°C to 125°C, which exceeds the original -55°C to 105°C specification. The substitute provides additional thermal margin for high-temperature applications.

Q: How do the Q factor values compare?

A: The 74F685AI-RC has Q of 90 @ 2.52 MHz; the 1945R-18J has Q of 75 @ 2.5 MHz. The lower Q in the substitute reflects differences in core material and construction. Evaluate this parameter if circuit performance depends on inductor quality factor at these frequencies.