BFS17,235 RF Transistor NPN Equivalent & Substitute Parts

Part Overview

The BFS17,235 is an RF transistor NPN manufactured by NXP USA Inc., designed for RF applications operating at 1GHz transition frequency with 15V collector-emitter breakdown voltage and 300mW maximum power dissipation in a surface mount SOT-23 (TO-236AB) package. This part is classified as obsolete, necessitating identification of active equivalent and substitute components that maintain functional compatibility within specified electrical and mechanical parameters.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	-
Voltage - Collector Emitter Breakdown (Max)	15V	V
Frequency - Transition	1GHz	GHz
Power - Max	300mW	mW
Current - Collector (Ic) (Max)	25mA	mA
DC Current Gain (hFE) (Min) @ Ic, Vce	25 @ 2mA, 1V	-
Noise Figure (dB Typ @ f)	4.5dB @ 500MHz	dB
Operating Temperature (Max)	150°C	°C
Mounting Type	Surface Mount	-
Package / Case	TO-236-3, SC-59, SOT-23-3	-
RoHS Status	ROHS3 Compliant	-
Moisture Sensitivity Level (MSL)	1 (Unlimited)	-

Substitute Part Grouping Explanation

Substitution of the BFS17,235 is determined by the following critical parameters:

Primary Compatibility Criteria:

Transistor Type: NPN (mandatory match)
Voltage - Collector Emitter Breakdown (Max): 15V or higher (backward compatible)
Mounting Type: Surface Mount (mandatory match)
Package compatibility: SOT-23-3 (TO-236AB) or equivalent footprint

Secondary Performance Criteria:

Frequency - Transition: 1GHz or higher (backward compatible for RF applications)
Power - Max: 300mW or higher (backward compatible)
Current - Collector (Ic) (Max): 25mA or higher (backward compatible)
Operating Temperature: 150°C maximum junction temperature (mandatory match)

Compliance Requirements:

RoHS3 Compliant (mandatory match)
Moisture Sensitivity Level: 1 (Unlimited) (mandatory match)

Substitute parts are grouped into two categories:

Category A - Direct Package Compatibility (SOT-23-3): Parts maintaining identical or compatible SOT-23-3 package footprint with electrical parameters meeting or exceeding the BFS17,235 specifications.

Category B - Alternative Package Compatibility (SOT-343, TSLP-3-1, TSFP-3): Parts with superior electrical performance but different surface mount packages requiring PCB layout modification.

Parameter Comparison

Parameter	BFS17,235 (Main)	BFU520AR	BFR193L3E6327XTMA1	BFP183WH6327XTSA1	BFR340FH6327XTSA1	BFS 17P E8211	MMBT918LT1G
Manufacturer	NXP USA Inc.	NXP USA Inc.	Infineon Technologies	Infineon Technologies	Infineon Technologies	Infineon Technologies	onsemi
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	15V	12V	12V	12V	9V	15V	15V
Frequency - Transition	1GHz	10GHz	8GHz	8.5GHz	14GHz	1.4GHz	600MHz
Noise Figure (dB Typ @ f)	4.5dB @ 500MHz	0.7dB @ 900MHz	1dB ~ 1.6dB @ 900MHz ~ 1.8GHz	0.9dB ~ 1.4dB @ 900MHz ~ 1.8GHz	0.9dB ~ 1.2dB @ 100MHz ~ 2.4GHz	3.5dB @ 800MHz	6dB @ 60MHz
Power - Max	300mW	450mW	580mW	450mW	75mW	280mW	225mW
DC Current Gain (hFE) (Min) @ Ic, Vce	25 @ 2mA, 1V	60 @ 5mA, 8V	70 @ 30mA, 8V	70 @ 15mA, 8V	90 @ 5mA, 3V	40 @ 2mA, 1V	20 @ 3mA, 1V
Current - Collector (Ic) (Max)	25mA	30mA	80mA	65mA	20mA	25mA	50mA
Operating Temperature (Max)	150°C	150°C	150°C	150°C	150°C	150°C	150°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	SC-101, SOT-883	SC-82A, SOT-343	SOT-723	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Direct Replacement (No PCB Modification Required):

BFS 17P E8211 (Infineon Technologies) - Recommended for direct substitution. This part maintains identical SOT-23-3 package footprint, matching 15V collector-emitter breakdown voltage, and equivalent 25mA maximum collector current. Transition frequency of 1.4GHz exceeds the 1GHz specification. Product status is active with full RoHS3 compliance and MSL 1 rating. Operating temperature maximum of 150°C matches the original specification.

MMBT918LT1G (onsemi) - Alternative direct replacement with SOT-23-3 package compatibility. Maintains 15V collector-emitter breakdown voltage and 25mA maximum collector current. Transition frequency of 600MHz is lower than the original 1GHz specification, limiting application to lower frequency RF circuits. Product status is active with full RoHS3 compliance and MSL 1 rating. Extended operating temperature range of -55°C to 150°C provides additional thermal margin.

Enhanced Performance Substitutes (PCB Layout Modification Required):

BFU520AR (NXP USA Inc.) - Manufacturer-recommended substitute offering superior RF performance. Provides 10GHz transition frequency with 450mW power dissipation. Collector-emitter breakdown voltage of 12V is lower than the original 15V specification. Requires SOT-23-3 package footprint compatibility verification. Includes AEC-Q101 automotive qualification. Product status is active with full RoHS3 compliance.

BFR193L3E6327XTMA1 (Infineon Technologies) - High-performance alternative with 8GHz transition frequency and 580mW power dissipation. Collector-emitter breakdown voltage of 12V is lower than the original 15V specification. Package is PG-TSLP-3-1 (SOT-883), requiring PCB layout modification. Maximum collector current of 80mA exceeds original specification. Product status is active with full RoHS3 compliance.

BFP183WH6327XTSA1 (Infineon Technologies) - High-performance alternative with 8.5GHz transition frequency and 450mW power dissipation. Collector-emitter breakdown voltage of 12V is lower than the original 15V specification. Package is PG-SOT343-3D (SOT-343), requiring PCB layout modification. Maximum collector current of 65mA exceeds original specification. Product status is active with full RoHS3 compliance.

BFR340FH6327XTSA1 (Infineon Technologies) - Ultra-high-frequency alternative with 14GHz transition frequency. Collector-emitter breakdown voltage of 9V is significantly lower than the original 15V specification, limiting application to lower voltage circuits. Power dissipation of 75mW is substantially lower than the original 300mW specification. Package is PG-TSFP-3 (SOT-723), requiring PCB layout modification. Maximum collector current of 20mA is lower than original specification. Product status is active with full RoHS3 compliance.

Frequently Asked Questions (FAQ)

Q1: Can BFS 17P E8211 be used as a direct drop-in replacement for BFS17,235?

A: Yes. BFS 17P E8211 maintains identical SOT-23-3 package footprint, matching 15V collector-emitter breakdown voltage, and equivalent 25mA maximum collector current. No PCB layout modification is required. The 1.4GHz transition frequency exceeds the original 1GHz specification, providing enhanced RF performance capability.

Q2: What is the primary difference between direct replacement options and enhanced performance substitutes?

A: Direct replacement options (BFS 17P E8211 and MMBT918LT1G) maintain the SOT-23-3 package footprint, allowing component substitution without PCB modification. Enhanced performance substitutes (BFU520AR, BFR193L3E6327XTMA1, BFP183WH6327XTSA1, BFR340FH6327XTSA1) offer superior RF performance characteristics but require alternative package footprints (SOT-343, SOT-883, SOT-723), necessitating PCB layout redesign.

Q3: Why does BFR340FH6327XTSA1 have lower power dissipation than the original BFS17,235?

A: BFR340FH6327XTSA1 is optimized for ultra-high-frequency operation (14GHz) in miniaturized applications. The 75mW power rating reflects design optimization for lower power RF circuits. This part is suitable only for applications where the lower power dissipation and reduced collector current (20mA maximum) are compatible with circuit requirements.

Q4: Can parts with 12V collector-emitter breakdown voltage replace the 15V BFS17,235 in all applications?

A: No. Parts with 12V collector-emitter breakdown voltage (BFU520AR, BFR193L3E6327XTMA1, BFP183WH6327XTSA1) are suitable only for circuits operating at 12V or lower. Applications requiring 15V operation must use BFS 17P E8211 or MMBT918LT1G, which maintain the original 15V specification.

Q5: What compliance certifications are maintained across all substitute parts?

A: All substitute parts maintain RoHS3 compliance and Moisture Sensitivity Level 1 (Unlimited) rating, matching the original BFS17,235 specifications. BFU520AR includes additional AEC-Q101 automotive qualification. All parts are REACH unaffected and classified as EAR99 for export control purposes.

Q6: Is MMBT918LT1G suitable for 1GHz RF applications?

A: MMBT918LT1G has a transition frequency of 600MHz, which is lower than the 1GHz specification of the original BFS17,235. This part is suitable for RF applications operating at frequencies below 600MHz. For applications requiring 1GHz or higher frequency operation, BFS 17P E8211 or enhanced performance substitutes are required.

Q7: What PCB layout considerations apply when substituting with alternative package options?

A: Alternative package options require PCB footprint redesign. BFR193L3E6327XTMA1 uses PG-TSLP-3-1 (SOT-883) package; BFP183WH6327XTSA1 uses PG-SOT343-3D (SOT-343) package; BFR340FH6327XTSA1 uses PG-TSFP-3 (SOT-723) package. Each package has different pin spacing, lead geometry, and thermal characteristics requiring circuit board redesign and re-qualification.

Q8: Are all substitute parts currently in active production status?

A: Yes. All substitute parts listed are classified as active products. The original BFS17,235 is classified as obsolete, making identification of active alternatives necessary for new designs and production continuity.

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