Bourns 78F1R8K Equivalent & Substitute Parts

Part Overview

The Bourns 78F1R8K is a 1.8 µH unshielded drum core wirewound inductor rated for 455 mA with a maximum DC resistance of 250mOhm. This through-hole axial component operates across -55°C to 105°C and features ferrite core construction with ±10% inductance tolerance. The 78F series is classified as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications.

Substiute Parts

78F1R8K

Bourns Inc.In Stock: 125078F1R8K Datasheet

Current PartRFQ

8230-26-RC

Bourns Inc.In Stock: 20938230-26-RC Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 78F1R8K is based on the following critical parameters that must remain constant or compatible:

• Inductance Value: 1.8 µH (exact match required)
• Inductance Tolerance: ±10% (must be equivalent or tighter)
• Core Type: Ferrite, unshielded drum core (electrical and mechanical compatibility)
• Mounting Configuration: Through-hole axial (PCB assembly compatibility)
• Operating Temperature Range: -55°C to 105°C (application environment compatibility)
• Test Frequency: 7.9 MHz (performance verification baseline)

The Bourns 8230-26-RC qualifies as a substitute because it maintains identical inductance, tolerance, core material, shielding type, mounting method, temperature range, and test frequency. Variations in current rating, DC resistance, and physical dimensions are acceptable when the substitute part meets or exceeds the electrical requirements of the application.

Parameter Comparison

Engineering Selection Recommendations

The Bourns 8230-26-RC is the qualified substitute for the obsolete 78F1R8K based on the following factors:

Electrical Compatibility: Both parts maintain identical inductance (1.8 µH), tolerance (±10%), core material (ferrite), and operating temperature range (-55°C to 105°C). The substitute's higher current rating (640 mA versus 455 mA) and marginally higher DC resistance (300mOhm versus 250mOhm) do not compromise functionality in applications designed for the original part.

Manufacturing Status: The 78F1R8K is obsolete with no ongoing production. The 8230-26-RC is actively manufactured by Bourns Inc., ensuring long-term availability and supply chain continuity.

Regulatory Compliance: The 8230-26-RC is ROHS3 compliant, meeting current environmental and regulatory requirements. The original 78F1R8K is RoHS non-compliant, making the substitute preferable for new designs and updated production runs.

Physical Considerations: The substitute is marginally larger (0.120" diameter × 0.300" length versus 0.110" diameter × 0.280" length). Verify that PCB layout and component spacing accommodate the increased dimensions before implementation.

Quality Factor (Q): The substitute exhibits lower Q at 7.9 MHz (30 versus 50). For applications where high Q is critical to circuit performance, conduct circuit simulation or prototype testing to confirm acceptable performance margins.

Frequently Asked Questions (FAQ)

Q: Can the 8230-26-RC be used as a direct replacement for the 78F1R8K in existing designs?

A: Yes, provided that PCB layout accommodates the slightly larger physical dimensions (0.120" diameter × 0.300" length). The electrical parameters—inductance, tolerance, core material, and operating temperature—are identical. Verify that the lower Q factor (30 versus 50 at 7.9 MHz) does not impact circuit performance in your specific application.

Q: What is the significance of the higher current rating in the 8230-26-RC?

A: The 8230-26-RC is rated for 640 mA compared to the 78F1R8K's 455 mA. This higher rating provides additional thermal margin and allows the substitute to handle greater current loads without saturation. For applications operating at or below 455 mA, this difference is not a limiting factor.

Q: Does the increased DC resistance of the 8230-26-RC affect circuit performance?

A: The 8230-26-RC has a maximum DC resistance of 300mOhm compared to 250mOhm for the 78F1R8K. This 50mOhm difference is marginal and typically acceptable in most applications. However, in circuits where inductor losses directly impact efficiency or signal integrity, calculate the power dissipation difference to confirm acceptability.

Q: Why is RoHS compliance important for this substitution?

A: The 8230-26-RC is ROHS3 compliant, while the 78F1R8K is not. RoHS compliance is mandatory for products sold in the European Union and increasingly required by global manufacturers. Using the compliant substitute ensures regulatory adherence and future-proofs your design against evolving environmental standards.

Q: Are there any frequency-dependent differences between these parts?

A: Both parts are tested at 7.9 MHz and share an identical self-resonant frequency of 125 MHz. The primary frequency-dependent difference is the Q factor: the 78F1R8K exhibits Q of 50 at 7.9 MHz, while the 8230-26-RC exhibits Q of 30. For applications operating near the self-resonant frequency or requiring high selectivity, evaluate whether the lower Q is acceptable.

Q: What should I verify before implementing the 8230-26-RC in production?

A: Confirm that your PCB layout provides adequate clearance for the substitute's larger dimensions. If your circuit relies on the higher Q factor of the original part, conduct prototype testing or circuit simulation to verify performance. For high-frequency or precision applications, measure the actual inductance and Q of sample parts to confirm they meet your design specifications.