BFS17W,135 RF Transistor NPN Equivalent & Substitute Parts

Part Overview

The BFS17W,135 is an RF transistor NPN manufactured by NXP USA Inc., designed for wideband RF applications operating at 1.6GHz with a maximum power dissipation of 300mW. This component is packaged in SC-70 (SOT-323-3) surface mount configuration and rated for 15V collector-emitter breakdown voltage with 50mA maximum collector current.

The BFS17W,135 is classified as obsolete. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this RF transistor specification.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	15V	V
Frequency - Transition	1.6GHz	GHz
Power - Max	300mW	mW
Current - Collector (Ic) (Max)	50mA	mA
DC Current Gain (hFE) (Min) @ Ic, Vce	25 @ 2mA, 1V	—
Noise Figure (dB Typ @ f)	4.5dB @ 500MHz	dB
Operating Temperature (Max)	175°C	°C
Mounting Type	Surface Mount	—
Package / Case	SC-70, SOT-323	—
RoHS Status	ROHS3 Compliant	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the BFS17W,135 is determined by the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (mandatory match)
Voltage - Collector Emitter Breakdown (Max): ≥15V (equal or higher rating required)
Current - Collector (Ic) (Max): ≥50mA (equal or higher rating required)
Frequency - Transition: ≥1.6GHz (equal or higher frequency capability required)
Power - Max: ≥300mW (equal or higher power dissipation required)
Mounting Type: Surface Mount (package form factor compatibility)

Secondary Compatibility Factors:

DC Current Gain (hFE): Minimum 25 @ specified conditions
Noise Figure: Performance at RF frequencies
Operating Temperature: Maximum junction temperature ≥150°C preferred for thermal margin
Compliance: RoHS3 compliance preferred for regulatory alignment

Substitute parts are grouped into two categories:

Category A - Direct Functional Equivalents (Active Status): Parts meeting or exceeding all primary substitution criteria with active product status and RoHS3 compliance. These parts are suitable for direct replacement in new designs and ongoing production.

Category B - Performance-Enhanced Alternatives (Active Status): Parts exceeding primary criteria with enhanced frequency capability, improved noise figure, or higher power ratings. These parts provide superior performance characteristics and are suitable for applications requiring enhanced RF performance.

Parameter Comparison

Part Number	Manufacturer	Vce (Max) [V]	Ic (Max) [mA]	Frequency [GHz]	Power (Max) [mW]	hFE (Min)	Noise Figure [dB]	Package	Status	RoHS
BFS17W,135	NXP USA Inc.	15	50	1.6	300	25	4.5 @ 500MHz	SC-70, SOT-323	Obsolete	ROHS3
BFU550WX	NXP Semiconductors	12	50	11	450	60	1.3 @ 1.8GHz	SC-70, SOT-323	Obsolete	Non-compliant
BFP182RE7764HTSA1	Infineon Technologies	12	35	8	250	70	0.9-1.3 @ 900MHz-1.8GHz	SOT-143R	Active	ROHS3
BFP420H6433XTMA1	Infineon Technologies	5	35	25	160	60	1.1 @ 1.8GHz	SC-82A, SOT-343	Active	ROHS3
BFP640H6327XTSA1	Infineon Technologies	4.5	50	40	200	110	0.65-1.2 @ 1.8GHz-6GHz	SC-82A, SOT-343	Active	ROHS3
BFP840ESDH6327XTSA1	Infineon Technologies	2.25	35	80	75	150	0.85 @ 5.5GHz	SC-82A, SOT-343	Active	ROHS3
BFS 17P E6433	Infineon Technologies	15	25	1.4	280	40	3.5-5 @ 800MHz	TO-236-3, SC-59, SOT-23-3	Active	ROHS3
MRF327	MACOM Technology Solutions	33	9000	—	80000	20	—	316-01	Active	ROHS3

Engineering Selection Recommendations

For Direct Replacement (Voltage and Current Compatibility):

The BFS 17P E6433 (Infineon Technologies) is the closest functional equivalent. It maintains the 15V collector-emitter breakdown voltage rating of the original BFS17W,135 and operates at comparable frequency (1.4GHz vs. 1.6GHz). This part is active status with ROHS3 compliance. The primary trade-off is reduced maximum collector current (25mA vs. 50mA) and different package form factor (SOT-23-3 vs. SC-70). This substitution is suitable for applications where the 25mA current rating is sufficient.

For Enhanced RF Performance (Higher Frequency Applications):

The BFP182RE7764HTSA1 (Infineon Technologies) provides 8GHz frequency capability with improved noise figure (0.9-1.3dB vs. 4.5dB) and higher DC current gain (70 vs. 25). This part is active status with ROHS3 compliance. The trade-off is reduced voltage rating (12V vs. 15V) and reduced maximum collector current (35mA vs. 50mA). This substitution is suitable for applications requiring enhanced RF performance at frequencies up to 8GHz where the 12V voltage rating is acceptable.

For Ultra-High Frequency Applications (40GHz+):

The BFP640H6327XTSA1 (Infineon Technologies) provides 40GHz frequency capability with superior noise figure (0.65-1.2dB) and highest DC current gain (110). This part is active status with ROHS3 compliance and maintains 50mA maximum collector current. The trade-off is significantly reduced voltage rating (4.5V vs. 15V). This substitution is suitable only for applications operating at 40GHz where the 4.5V voltage rating is compatible with circuit design.

Compliance and Regulatory Considerations:

All recommended active substitutes (BFP182RE7764HTSA1, BFP420H6433XTMA1, BFP640H6327XTSA1, BFP840ESDH6327XTSA1, BFS 17P E6433) maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory alignment with current environmental and hazardous substance directives.

The BFU550WX is not recommended despite enhanced performance characteristics due to non-compliant RoHS status, which creates regulatory risk for new designs and ongoing production.

The MRF327 is a fundamentally different device class (high-power chassis mount RF transistor, 33V/9A/80W) and is not suitable as a substitute for the BFS17W,135 (low-power surface mount RF transistor, 15V/50mA/300mW).

Frequently Asked Questions (FAQ)

Q1: Can the BFS17W,135 be directly replaced with the BFS 17P E6433?

A: The BFS 17P E6433 is functionally compatible for applications where the maximum collector current requirement does not exceed 25mA. Both parts maintain 15V collector-emitter breakdown voltage and operate at comparable frequencies (1.4GHz vs. 1.6GHz). The primary limitation is the reduced current rating and different package form factor (SOT-23-3 vs. SC-70). PCB layout modifications may be required due to package differences.

Q2: What is the primary reason the BFU550WX is not recommended as a substitute?

A: The BFU550WX is classified as non-compliant with RoHS regulations. While it offers superior RF performance (11GHz frequency, 1.3dB noise figure, 450mW power), its non-compliant status creates regulatory risk for new product designs and ongoing production in markets requiring RoHS compliance. All active Infineon alternatives maintain ROHS3 compliance.

Q3: Which substitute part is suitable for applications requiring voltage ratings above 12V?

A: The BFS 17P E6433 maintains the 15V collector-emitter breakdown voltage rating of the original BFS17W,135. This is the only active substitute that preserves the original voltage specification. All other active substitutes operate at reduced voltage ratings (12V, 5V, 4.5V, or 2.25V).

Q4: Can the BFP640H6327XTSA1 be used in place of the BFS17W,135 in existing designs?

A: The BFP640H6327XTSA1 is not suitable for direct replacement in existing designs due to significantly reduced voltage rating (4.5V vs. 15V). This part is designed for ultra-high frequency applications (40GHz) where circuit voltage levels are compatible with 4.5V operation. Use of this part in circuits designed for 15V operation will result in component failure.

Q5: What are the key package compatibility considerations when substituting RF transistors?

A: The BFS17W,135 uses SC-70 (SOT-323) package. The BFS 17P E6433 uses SOT-23-3 package, which has different pin spacing and footprint. The Infineon BFP series parts (BFP182, BFP420, BFP640, BFP840) use SOT-343 or SOT-143R packages with different pin configurations. Package substitution requires PCB layout redesign and verification of pin assignments before implementation.

Q6: Which substitute provides the best noise figure performance?

A: The BFP840ESDH6327XTSA1 provides the lowest noise figure (0.85dB @ 5.5GHz), followed by BFP640H6327XTSA1 (0.65-1.2dB @ 1.8GHz-6GHz). However, both parts operate at significantly reduced voltage ratings (2.25V and 4.5V respectively) compared to the original 15V specification. Noise figure improvement must be evaluated against voltage rating compatibility with the target application.

Q7: Is the MRF327 a suitable substitute for the BFS17W,135?

A: No. The MRF327 is a fundamentally different device class. It is a high-power chassis mount RF transistor rated for 33V/9A/80W operation, whereas the BFS17W,135 is a low-power surface mount RF transistor rated for 15V/50mA/300mW. Package type (316-01 chassis mount vs. SC-70 surface mount), current rating (9A vs. 50mA), and power rating (80W vs. 300mW) are incompatible. This part is not suitable for applications designed around the BFS17W,135 specification.

Q8: What compliance certifications should be verified when selecting a substitute?

A: All recommended active substitutes maintain ROHS3 compliance and REACH unaffected status. Verify that the selected substitute meets the specific regulatory requirements of the target market and application. The BFU550WX does not meet RoHS compliance and should not be used in new designs or production requiring regulatory compliance.

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