BFS520,115 Equivalent & Substitute Parts

Part Overview

The BFS520,115 is an RF transistor manufactured by NXP USA Inc., classified as an NPN bipolar junction transistor (BJT) designed for high-frequency applications. This device operates at frequencies up to 9GHz with a maximum collector-emitter breakdown voltage of 15V and a power dissipation rating of 300mW in a surface mount SC-70 package.

The BFS520,115 is designated as obsolete. Locating equivalent or substitute components is necessary to support ongoing production requirements, maintenance operations, and system redesigns where this part is specified in existing designs.

Substiute Parts

BFS520,115

NXP USA Inc.In Stock: 1024BFS520,115 Datasheet

Current PartRFQ

BFU550WX

NXP SemiconductorsIn Stock: 4466BFU550WX Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BFS520,115 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

• Transistor type must be NPN
• Collector-emitter breakdown voltage must equal or exceed the application requirement (15V minimum for BFS520,115)
• Transition frequency must support the intended operating frequency (9GHz minimum)
• Maximum collector current must accommodate circuit design specifications (70mA maximum for BFS520,115)
• Power dissipation rating must support thermal requirements (300mW minimum for BFS520,115)
• DC current gain (hFE) must fall within acceptable operating ranges

Mechanical Compatibility Criteria:

• Package type must be SC-70 or SOT-323 (surface mount, three-terminal configuration)
• Pin configuration must be compatible with existing PCB layouts

The BFU550WX is identified as a manufacturer-recommended substitute based on these parameters.

Parameter Comparison

Engineering Selection Recommendations

BFU550WX as Substitute:

The BFU550WX is identified as a manufacturer-recommended substitute for the BFS520,115. Both devices are classified as obsolete and share identical package configurations (SC-70/SOT-323 surface mount).

Electrical Considerations:

The BFU550WX demonstrates superior transition frequency (11GHz versus 9GHz) and higher power dissipation capability (450mW versus 300mW). However, the BFU550WX has a lower maximum collector-emitter breakdown voltage (12V versus 15V) and lower maximum collector current rating (50mA versus 70mA). Circuit designs must confirm that application voltage and current requirements fall within the BFU550WX specifications.

Compliance Considerations:

The BFS520,115 is ROHS3 compliant with MSL rating of 1 (unlimited moisture sensitivity). The BFU550WX is RoHS non-compliant. Applications subject to RoHS regulatory requirements cannot use the BFU550WX as a direct substitute without design review and compliance documentation.

Both devices carry ECCN classification EAR99 and HTSUS code 8541.21.0075.

Frequently Asked Questions (FAQ)

Q: Can the BFU550WX directly replace the BFS520,115 in all applications?

A: Direct replacement requires verification of three critical parameters: (1) application voltage must not exceed 12V collector-emitter breakdown voltage, (2) circuit collector current must not exceed 50mA maximum, and (3) regulatory compliance requirements must accommodate RoHS non-compliant status. The BFU550WX is electrically suitable for applications meeting these constraints.

Q: What is the primary difference between these two parts?

A: The BFS520,115 is rated for higher voltage (15V) and higher current (70mA) with lower maximum frequency (9GHz). The BFU550WX is rated for higher frequency (11GHz) and higher power dissipation (450mW) but with lower voltage and current ratings. Selection depends on specific circuit requirements.

Q: Are the packages identical?

A: Yes. Both the BFS520,115 and BFU550WX use the SC-70 surface mount package, also designated SOT-323. Pin configuration and PCB footprint are compatible.

Q: What does "obsolete" status mean for these parts?

A: Both devices are designated as obsolete by the manufacturer, indicating they are no longer in active production. Existing inventory may be available through authorized distributors, but long-term availability is not guaranteed. New designs should consider current-generation RF transistor alternatives.

Q: Does the noise figure difference affect substitution suitability?

A: The noise figures are measured at different frequencies (900MHz for BFS520,115 versus 1.8GHz for BFU550WX), making direct comparison imprecise. Circuit performance at the intended operating frequency must be evaluated through application-specific testing or simulation.

Q: What is the significance of the RoHS compliance difference?

A: The BFS520,115 is ROHS3 compliant; the BFU550WX is not. Applications subject to RoHS directives (EU and equivalent regulations) cannot use the BFU550WX without regulatory approval or design modification. Compliance requirements must be confirmed before substitution.