Bourns 78F100J Fixed Inductor - Equivalent & Substitute Parts

Part Overview

The Bourns 78F100J is a 10 µH unshielded drum core wirewound inductor rated for 130 mA with a maximum DC resistance of 720 mOhm. This through-hole axial component operates across the temperature range of -55°C to 105°C and is designed for applications requiring fixed inductance in compact form factors.

The 78F100J has reached obsolete product status. Locating equivalent or substitute components is necessary to support ongoing maintenance, repair, and redesign efforts for legacy systems utilizing this inductor.

Substiute Parts

78F100J

Bourns Inc.In Stock: 118778F100J Datasheet

Current PartRFQ

78F100J-RC

Bourns Inc.In Stock: 974778F100J-RC Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 78F100J is determined by the following critical parameters:

• Inductance Value: Must remain 10 µH with ±5% tolerance
• Core Type & Shielding: Ferrite material, unshielded configuration
• Mounting & Package: Through-hole axial form factor with identical physical dimensions (0.110" Dia × 0.280" L)
• Operating Temperature: -55°C to 105°C range
• Frequency Characteristics: Q factor and self-resonant frequency within acceptable application limits

The 78F100J-RC meets these substitution criteria. While it exhibits higher current rating (370 mA vs. 130 mA) and slightly elevated DC resistance (750 mOhm vs. 720 mOhm), these parameters remain within acceptable tolerances for equivalent functionality. The substitute maintains identical inductance, core material, shielding configuration, physical dimensions, and operating temperature range.

Parameter Comparison

Engineering Selection Recommendations

The 78F100J-RC is the direct substitute for the obsolete 78F100J. Selection of the 78F100J-RC is supported by the following factors:

• Product Status: The 78F100J-RC maintains active product status with established supply chain availability, whereas the 78F100J is obsolete.
• Regulatory Compliance: The 78F100J-RC is ROHS3 compliant, meeting current environmental and regulatory requirements. The original 78F100J is non-compliant with modern standards.
• Electrical Equivalence: Both components share identical inductance (10 µH), tolerance (±5%), core material (ferrite), shielding (unshielded), and operating temperature range (-55°C to 105°C).
• Physical Compatibility: Identical axial through-hole package dimensions (0.110" Dia × 0.280" L) ensure direct mechanical substitution without PCB layout modification.
• Performance Margin: The 78F100J-RC provides higher current rating (370 mA) compared to the original specification (130 mA), offering improved headroom for circuit operation.

Frequently Asked Questions (FAQ)

Q: Can the 78F100J-RC be used as a direct replacement for the 78F100J?

A: Yes. The 78F100J-RC is electrically and mechanically equivalent. Both components maintain 10 µH inductance, ±5% tolerance, ferrite core construction, unshielded configuration, and identical physical dimensions. The substitute is a direct pin-compatible replacement suitable for through-hole PCB assembly without design modification.

Q: What is the significance of the higher current rating in the 78F100J-RC?

A: The 78F100J-RC is rated for 370 mA compared to the original 130 mA specification. This higher current rating provides additional operational margin and does not affect substitution compatibility. Applications operating within the original 130 mA specification will function identically with the substitute component.

Q: How do the DC resistance values compare?

A: The 78F100J specifies 720 mOhm maximum DC resistance, while the 78F100J-RC specifies 750 mOhm maximum. This 30 mOhm difference (4.2% variance) is within acceptable engineering tolerance for equivalent component substitution and will not materially affect circuit performance in typical applications.

Q: What is the difference in self-resonant frequency between these components?

A: The 78F100J exhibits a self-resonant frequency of 22 MHz, while the 78F100J-RC is specified at 18 MHz. Both values remain well above the 7.9 MHz test frequency and support equivalent high-frequency performance characteristics. The Q factor at 7.9 MHz is identical (40) for both components.

Q: Are there packaging or mounting differences?

A: No. Both the 78F100J and 78F100J-RC utilize identical through-hole axial packaging with dimensions of 0.110" diameter by 0.280" length (2.79 mm × 7.11 mm). No PCB layout or assembly process modifications are required for substitution.

Q: Why is RoHS compliance important for this substitution?

A: The 78F100J-RC is ROHS3 compliant, meeting current environmental regulations and industry standards. The original 78F100J is non-compliant. For new designs, repair operations subject to regulatory requirements, or supply chain integration with modern component sourcing, the compliant 78F100J-RC is the appropriate selection.