BF494_D74Z Equivalent & Substitute Parts

Part Overview

The BF494_D74Z is an RF transistor NPN manufactured by onsemi, rated for 20V collector-emitter breakdown voltage with a maximum power dissipation of 350mW in a through-hole TO-92-3 package. This component is classified as obsolete, necessitating identification of equivalent substitute parts for ongoing design requirements and production continuity. Substitute parts must maintain functional compatibility within RF applications while accommodating differences in packaging, voltage ratings, and current handling capabilities.

Substiute Parts

BF494_D74Z

onsemiIn Stock: 1184BF494_D74Z Datasheet

Current PartRFQ

BFP740FESDH6327XTSA1

Infineon TechnologiesIn Stock: 6064BFP740FESDH6327XTSA1 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 BF494_D74Z is determined by the following critical parameters: transistor type (NPN), voltage rating (20V maximum), power dissipation capability (350mW), collector current rating (30mA), and operating temperature range (150°C). The three identified substitute parts represent different application categories based on these specifications.

Substitution Logic:

The BFP740FESDH6327XTSA1 and BFR460L3E6326XTMA1 are high-frequency RF transistors with significantly lower voltage ratings (4.7V and 5.8V respectively) and reduced power dissipation (160mW and 200mW). These parts are suitable for applications where the BF494_D74Z operates at lower supply voltages and lower power levels, particularly in microwave and millimeter-wave frequency bands.

The MRF455 is a high-power RF transistor rated for 18V with substantially higher power dissipation (60W) and collector current capability (15A). This part is applicable for applications requiring higher power handling than the BF494_D74Z, such as RF power amplification in industrial and communications equipment.

All substitute parts maintain NPN transistor type and 150°C maximum operating temperature compatibility with the original component.

Parameter Comparison

Engineering Selection Recommendations

BFP740FESDH6327XTSA1 Selection Criteria:

This Infineon Technologies part is suitable for RF applications operating at supply voltages of 4.7V or lower. The active product status and ROHS3 compliance provide long-term availability and regulatory alignment. Surface mount packaging requires PCB redesign compared to the through-hole BF494_D74Z. The 47GHz transition frequency and 0.5dB to 1.45dB noise figure specification indicate suitability for high-frequency microwave applications. Selection is appropriate when voltage and power requirements are within the specified limits.

BFR460L3E6327XTMA1 Selection Criteria:

This Infineon Technologies part operates at 5.8V maximum with 22GHz transition frequency, suitable for lower-frequency RF applications than the BFP740FESDH6327XTSA1. Active product status and ROHS3 compliance ensure supply chain continuity. Surface mount PG-TSLP-3-1 packaging requires circuit board modification. The 200mW power rating and 50mA collector current provide moderate power handling capability. Selection is appropriate for applications requiring lower frequency operation than the BFP740FESDH6327XTSA1 while maintaining active product availability.

MRF455 Selection Criteria:

This MACOM Technology Solutions part is rated for 18V operation with 60W power dissipation and 15A collector current, suitable for high-power RF amplification applications. Active product status and ROHS3 compliance support long-term procurement. Chassis mount packaging represents a significant form factor change from the BF494_D74Z. The 13dB gain specification and high power rating indicate suitability for RF power amplifier stages in industrial and communications systems. Selection is appropriate when application requirements exceed the 350mW power and 30mA current limits of the BF494_D74Z.

Frequently Asked Questions (FAQ)

Q: Can the BFP740FESDH6327XTSA1 directly replace the BF494_D74Z in existing designs?

A: Direct replacement is not possible due to three critical differences: voltage rating (4.7V versus 20V), mounting type (surface mount versus through hole), and package form factor (4-TSFP versus TO-92-3). Circuit redesign is required to accommodate the lower voltage rating and surface mount technology. PCB layout modifications are mandatory.

Q: What is the primary limitation when substituting the BFR460L3E6327XTMA1 for the BF494_D74Z?

A: The voltage rating of 5.8V is significantly lower than the BF494_D74Z 20V rating. Applications operating at supply voltages above 5.8V cannot use this substitute without circuit modification. Additionally, surface mount packaging requires PCB redesign compared to through-hole mounting.

Q: Is the MRF455 suitable for low-power RF applications originally designed for the BF494_D74Z?

A: The MRF455 is designed for high-power RF amplification with 60W dissipation and 15A collector current. While electrically compatible at 18V operation, this part is over-specified for applications requiring only 350mW power dissipation and 30mA collector current. The MRF455 is appropriate only for applications requiring substantially higher power handling than the original BF494_D74Z design.

Q: What packaging considerations apply when selecting substitute parts?

A: The BF494_D74Z uses through-hole TO-92-3 packaging. Both Infineon substitutes (BFP740FESDH6327XTSA1 and BFR460L3E6327XTMA1) require surface mount technology, necessitating PCB redesign. The MRF455 uses chassis mount packaging, requiring mechanical redesign of the mounting structure. Packaging selection depends on available manufacturing capabilities and circuit board design constraints.

Q: Are all substitute parts compliant with current regulatory requirements?

A: The BFP740FESDH6327XTSA1 and BFR460L3E6327XTMA1 are ROHS3 compliant. The MRF455 is ROHS3 compliant. All three substitute parts are REACH unaffected. The original BF494_D74Z is REACH unaffected but not ROHS3 compliant due to its obsolete status. Regulatory compliance should be verified against specific application requirements and regional standards.

Q: What frequency range considerations apply to these substitutes?

A: The BF494_D74Z does not specify transition frequency. The BFP740FESDH6327XTSA1 operates to 47GHz, suitable for millimeter-wave applications. The BFR460L3E6327XTMA1 operates to 22GHz, suitable for microwave applications. The MRF455 does not specify transition frequency but is designed for RF power amplification. Frequency capability must align with the intended application operating band.