Bourns 78F4R7J Equivalent & Substitute Parts

Part Overview

The Bourns 78F4R7J is a 4.7 µH unshielded drum core wirewound inductor rated for 230 mA with a maximum DC resistance of 350mOhm. 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 78F4R7J carries an obsolete product status. Identifying equivalent substitute parts is necessary to maintain design continuity and ensure component availability for production, repair, and redesign applications.

Substiute Parts

78F4R7J

Bourns Inc.In Stock: 84278F4R7J Datasheet

Current PartRFQ

78F4R7J-RC

Bourns Inc.In Stock: 655478F4R7J-RC Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 78F4R7J is determined by the following critical parameters:

• Inductance Value: Must be 4.7 µH with ±5% tolerance
• Core Type and Shielding: Must be ferrite drum core, unshielded construction
• Mounting and Package: Must be through-hole axial configuration with identical physical dimensions
• DC Resistance: Must not exceed 350mOhm maximum
• Operating Temperature Range: Must support -55°C to 105°C
• Q Factor and Frequency Characteristics: Must maintain Q @ 7.9MHz specification

The 78F4R7J-RC qualifies as a direct substitute based on matching all core electrical and mechanical parameters. The primary distinction is an increased current rating of 530 mA versus the original 230 mA specification, which represents an enhancement rather than a limitation for substitution purposes.

Parameter Comparison

Engineering Selection Recommendations

The 78F4R7J-RC is the qualified substitute for the obsolete 78F4R7J. Selection is based on the following factors:

Product Status: The 78F4R7J-RC maintains active product status with current manufacturing support, whereas the original 78F4R7J is obsolete and subject to availability constraints.

Compliance: The 78F4R7J-RC achieves ROHS3 compliance, meeting modern regulatory requirements. The original part is RoHS non-compliant, which may present procurement and environmental compliance challenges in new designs or production runs.

Electrical Equivalence: Both parts maintain identical inductance, tolerance, DC resistance, and frequency characteristics. The increased current rating of the substitute (530 mA versus 230 mA) provides additional design margin without compromising performance in applications designed for the original specification.

Physical Compatibility: Identical package dimensions and through-hole axial configuration ensure direct mechanical and electrical interchangeability in existing PCB layouts.

Frequently Asked Questions (FAQ)

Q: Can the 78F4R7J-RC be used as a direct replacement for the 78F4R7J in existing designs?

A: Yes. The 78F4R7J-RC is electrically and mechanically equivalent. Identical inductance, tolerance, DC resistance, and frequency characteristics ensure functional compatibility. The higher current rating represents an enhancement that does not affect performance in applications designed for the original part.

Q: What is the significance of the higher current rating in the 78F4R7J-RC?

A: The 78F4R7J-RC is rated for 530 mA compared to the original 230 mA. This increased rating provides additional thermal and electrical margin. Applications operating at or below 230 mA will experience no performance difference. Applications requiring higher current capacity benefit from the enhanced rating.

Q: Are there physical dimension differences between these parts?

A: No. Both parts share identical physical dimensions of 0.110" diameter by 0.280" length (2.79mm x 7.11mm). They are packaged in the same axial through-hole configuration and are directly interchangeable on PCBs designed for the 78F4R7J.

Q: What is the impact of RoHS compliance differences?

A: The 78F4R7J-RC is ROHS3 compliant, meeting current environmental and regulatory standards. The original 78F4R7J is RoHS non-compliant. For new production runs or designs subject to RoHS requirements, the 78F4R7J-RC is the appropriate selection.

Q: Are there frequency or Q factor differences?

A: No. Both parts maintain identical Q factor of 45 @ 7.9MHz and operate within the same frequency characteristics. The self-resonant frequency differs slightly (50MHz for the original versus 38MHz for the substitute), but this does not affect substitution eligibility for standard inductor applications.

Q: What packaging options are available for the 78F4R7J-RC?

A: The 78F4R7J-RC is supplied in bulk packaging, whereas the original 78F4R7J packaging specification is not detailed. For procurement purposes, confirm packaging requirements with the supplier to ensure compatibility with assembly processes.