78F221J Equivalent & Substitute Parts

Part Overview

The Bourns 78F221J is a 220 µH unshielded drum core wirewound inductor rated for 76 mA maximum current with 5.7Ω DC resistance. This through-hole axial component operates across -55°C to 105°C and is designed for applications requiring fixed inductance in compact form factors. The 78F221J is classified as obsolete, making identification of compatible substitutes essential for ongoing design support and production continuity.

Substiute Parts

78F221J

Bourns Inc.In Stock: 102878F221J Datasheet

Current PartRFQ

78F221J-RC

Bourns Inc.In Stock: 859878F221J-RC Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 78F221J is determined by the following critical parameters:

• Inductance Value: Must be 220 µH ±5%
• Core Type & Shielding: Ferrite material, unshielded configuration
• Mounting & Package: Through-hole axial form factor
• Operating Temperature Range: -55°C to 105°C minimum
• Physical Dimensions: 0.110" Dia x 0.280" L to ensure PCB compatibility
• Frequency Characteristics: Q @ 790kHz and 4MHz self-resonant frequency

The 78F221J-RC qualifies as a direct substitute based on matching inductance, core material, shielding type, mounting method, package style, temperature range, and physical dimensions. Variations in current rating and DC resistance are acceptable within the electrical design envelope when the primary inductance specification and form factor remain constant.

Parameter Comparison

Engineering Selection Recommendations

The 78F221J-RC is the qualified substitute for the obsolete 78F221J. Selection is based on the following engineering criteria:

Product Status: The 78F221J is obsolete with limited inventory availability (951 pcs). The 78F221J-RC is active with substantial stock (8547 pcs), ensuring long-term supply chain reliability.

Regulatory Compliance: The 78F221J-RC achieves ROHS3 compliance, whereas the original part is RoHS non-compliant. For applications subject to RoHS directives, the 78F221J-RC is the required choice.

Electrical Compatibility: Both parts maintain identical inductance (220 µH ±5%), core material (ferrite), shielding (unshielded), and frequency characteristics (Q @ 790kHz, 4MHz self-resonant frequency). The 78F221J-RC provides higher current rating (130 mA vs. 76 mA) and slightly elevated DC resistance (6.8Ω vs. 5.7Ω), representing acceptable trade-offs for applications operating within the original 76 mA specification.

Physical & Mechanical Compatibility: Identical axial through-hole package dimensions (0.110" Dia x 0.280" L) ensure direct PCB footprint compatibility without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can the 78F221J-RC directly replace the 78F221J in existing designs?

A: Yes. The 78F221J-RC maintains identical inductance value, tolerance, core material, shielding configuration, mounting type, package style, and physical dimensions. Direct substitution is electrically and mechanically compatible.

Q: What is the significance of the higher current rating on the 78F221J-RC?

A: The 78F221J-RC is rated for 130 mA versus the original 76 mA. This represents an enhanced current capability. Designs operating at or below 76 mA experience no functional change. The higher rating provides additional design margin and thermal headroom.

Q: Does the increased DC resistance of the 78F221J-RC affect circuit performance?

A: The 78F221J-RC exhibits 6.8Ω maximum DC resistance compared to 5.7Ω on the original part. This 1.1Ω increase is minimal for most applications. Power dissipation impact scales with I²R; at 76 mA, the additional loss is approximately 0.65 mW, typically negligible in circuit operation.

Q: Is the 78F221J-RC suitable for RoHS-regulated applications?

A: Yes. The 78F221J-RC is ROHS3 compliant, meeting RoHS Directive 2011/65/EU requirements. The original 78F221J is RoHS non-compliant and unsuitable for RoHS-regulated markets and applications.

Q: Are the physical dimensions identical between both parts?

A: Yes. Both the 78F221J and 78F221J-RC share identical axial through-hole dimensions of 0.110" Dia x 0.280" L (2.79mm x 7.11mm), ensuring PCB footprint compatibility without layout changes.

Q: What is the packaging difference between the two parts?

A: The 78F221J-RC is supplied in bulk packaging, whereas the original part packaging is not specified. For production environments, bulk packaging typically offers cost efficiency and reduced handling.