KSC1674CYBU Equivalent & Substitute Parts

Part Overview

The KSC1674CYBU is an RF transistor NPN manufactured by onsemi, rated for 20V collector-emitter breakdown voltage with a transition frequency of 600MHz and maximum power dissipation of 250mW. This device is packaged in a through-hole TO-92-3 configuration and is classified as obsolete. Due to its obsolete status, equivalent and substitute parts are necessary for ongoing design support, production continuity, and system maintenance applications requiring RF transistor functionality in the specified voltage and frequency range.

Substiute Parts

KSC1674CYBU

onsemiIn Stock: 65482KSC1674CYBU Datasheet

Current PartRFQ

BFP405H6740XTSA1

Infineon TechnologiesIn Stock: 961BFP405H6740XTSA1 Datasheet

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BFP640FESDH6327XTSA1

Infineon TechnologiesIn Stock: 3682BFP640FESDH6327XTSA1 Datasheet

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BFR460L3E6327XTMA1

Infineon TechnologiesIn Stock: 15936BFR460L3E6327XTMA1 Datasheet

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MRF455

MACOM Technology SolutionsIn Stock: 1824MRF455 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the KSC1674CYBU is determined by the following critical parameters: transistor type (NPN), maximum collector-emitter breakdown voltage, transition frequency capability, maximum power dissipation, maximum collector current, and DC current gain characteristics. Substitute parts must maintain NPN polarity and support the specified voltage and frequency operating ranges.

The substitute parts listed below are grouped into two categories based on their electrical and mechanical characteristics:

Category 1: Surface Mount RF Transistors with Enhanced Frequency Performance

• BFP405H6740XTSA1 (Infineon Technologies)
• BFP640FESDH6327XTSA1 (Infineon Technologies)
• BFR460L3E6327XTMA1 (Infineon Technologies)

These parts operate at higher transition frequencies (22GHz to 46GHz) and lower voltage ratings (4.7V to 5.8V) compared to the KSC1674CYBU. They are surface-mount devices suitable for applications requiring higher frequency performance within reduced voltage specifications.

Category 2: Chassis Mount RF Transistor with Higher Power Capability

• MRF455 (MACOM Technology Solutions)

This part operates at 18V maximum collector-emitter breakdown voltage with significantly higher power dissipation (60W) and collector current (15A), suitable for high-power RF applications.

Parameter Comparison

Engineering Selection Recommendations

For Direct Voltage and Frequency Compatibility: The KSC1674CYBU operates at 20V maximum collector-emitter breakdown voltage with 600MHz transition frequency. Among the listed substitutes, the MRF455 provides the closest voltage rating at 18V, making it suitable for applications where the original voltage specification must be maintained. However, the MRF455 is a chassis-mount device designed for high-power applications (60W), which differs significantly from the through-hole TO-92-3 package of the original part.

For Surface Mount Conversion with Reduced Voltage Operation: The Infineon Technologies parts (BFP405H6740XTSA1, BFP640FESDH6327XTSA1, and BFR460L3E6327XTMA1) are active products with ROHS3 compliance and represent modern surface-mount alternatives. These parts operate at reduced voltage ratings (4.7V to 5.8V) but provide significantly higher transition frequencies (22GHz to 46GHz). Selection among these three depends on specific application requirements for frequency performance and power dissipation within the reduced voltage envelope.

Product Status Consideration: All substitute parts carry active product status, ensuring ongoing manufacturer support and availability. The original KSC1674CYBU is obsolete, making substitution necessary for new designs or production continuity.

Frequently Asked Questions (FAQ)

Q: Can the BFP405H6740XTSA1, BFP640FESDH6327XTSA1, or BFR460L3E6327XTMA1 directly replace the KSC1674CYBU in existing through-hole designs?

A: No. These Infineon parts are surface-mount devices, while the KSC1674CYBU uses through-hole TO-92-3 packaging. Direct board-level substitution requires circuit board redesign to accommodate surface-mount footprints. Additionally, these parts operate at lower maximum collector-emitter breakdown voltages (4.7V to 5.8V) compared to the original 20V specification.

Q: What are the voltage limitations when substituting with Infineon surface-mount parts?

A: The BFP405H6740XTSA1 is rated for 5V maximum collector-emitter breakdown voltage, the BFP640FESDH6327XTSA1 for 4.7V, and the BFR460L3E6327XTMA1 for 5.8V. Applications requiring operation above these voltage levels cannot use these substitutes without circuit modification to reduce operating voltage.

Q: Is the MRF455 suitable for low-power RF applications originally designed for the KSC1674CYBU?

A: The MRF455 is designed for high-power RF applications with 60W maximum power dissipation and 15A maximum collector current. While it maintains a voltage rating close to the original (18V versus 20V), it is overspecified for applications requiring only 250mW power dissipation and 20mA collector current. The MRF455 also uses chassis-mount packaging, requiring different mechanical integration compared to the through-hole TO-92-3 package.

Q: What compliance certifications apply to the substitute parts?

A: All Infineon Technologies substitute parts (BFP405H6740XTSA1, BFP640FESDH6327XTSA1, and BFR460L3E6327XTMA1) are ROHS3 compliant. The MRF455 is also ROHS3 compliant. All parts listed carry REACH Unaffected or equivalent status and EAR99 export classification.

Q: How do the noise figure specifications compare between the original and substitute parts?

A: The KSC1674CYBU specifies 3dB to 5dB noise figure at 100MHz. The BFP405H6740XTSA1 provides 1.25dB at 1.8GHz, the BFP640FESDH6327XTSA1 provides 0.55dB to 1.7dB across 150MHz to 10GHz, and the BFR460L3E6327XTMA1 provides 1.1dB to 1.35dB at 1.8GHz to 3GHz. The Infineon parts demonstrate superior noise performance at their respective operating frequencies.

Q: What is the moisture sensitivity level for all listed parts?

A: All parts, including the original KSC1674CYBU and all substitutes, carry MSL 1 (Unlimited) moisture sensitivity level classification, indicating no moisture sensitivity restrictions.