BF959 Equivalent & Substitute Parts

Part Overview

The BF959 is an RF transistor NPN manufactured by onsemi, designed for radio frequency applications requiring operation at 700MHz with a maximum collector-emitter breakdown voltage of 20V and power dissipation of 625mW. The device is packaged in a through-hole TO-92 (TO-226-3) configuration and is classified as obsolete. Due to its obsolete status, equivalent substitute parts are necessary for new designs and ongoing production requirements. Substitute parts listed below provide comparable RF performance characteristics while offering active product status and modern packaging options.

Key Parameters

Parameter	BF959 Value	Unit
Transistor Type	NPN	-
Voltage - Collector Emitter Breakdown (Max)	20V	V
Frequency - Transition	700MHz	MHz
Noise Figure (Typ @ f)	3dB @ 200MHz	dB
Power - Max	625mW	mW
DC Current Gain (hFE) (Min)	40 @ 20mA, 10V	-
Current - Collector (Ic) (Max)	100mA	mA
Operating Temperature	-55°C ~ 150°C	°C
Mounting Type	Through Hole	-
Package / Case	TO-226-3, TO-92-3	-
Product Status	Obsolete	-
RoHS Status	RoHS non-compliant	-

Substitute Part Grouping Explanation

Substitute parts for the BF959 are evaluated based on the following critical parameters that determine functional equivalence:

Primary Substitution Criteria:

Transistor Type: NPN configuration required
Voltage Rating: Collector-emitter breakdown voltage must support 20V maximum operating conditions
Frequency Performance: Transition frequency must support RF operation at 700MHz and above
Power Dissipation: Maximum power rating must accommodate 625mW applications
Current Capability: Collector current rating must support 100mA maximum
Operating Temperature Range: Must support -55°C to 150°C junction temperature range

Substitution Categories:

Category 1 - High-Frequency Surface Mount Alternatives: Parts with significantly higher frequency capability (8GHz and above) and active product status, suitable for modern RF designs requiring surface mount packaging.

Category 2 - Moderate-Frequency Surface Mount Options: Parts with frequency ratings between 800MHz and 8.5GHz, offering improved performance over the BF959 while maintaining compatibility with RF circuit requirements.

Category 3 - High-Power Chassis Mount Alternative: Part with substantially higher power rating (60W) and current capability (15A), designed for high-power RF amplification applications.

Parameter Comparison

Parameter	BF959	2SC4713KT146R	BFR193L3E6327XTMA1	BFP740FESDH6327XTSA1	HFA3134IHZ96	MRF455
Manufacturer	onsemi	Rohm Semiconductor	Infineon Technologies	Infineon Technologies	Intersil	MACOM Technology Solutions
Transistor Type	NPN	NPN	NPN	NPN	2 NPN (Dual)	NPN
Voltage - Collector Emitter Breakdown (Max)	20V	6V	12V	4.7V	9V	18V
Frequency - Transition	700MHz	800MHz	8GHz	47GHz	8.5GHz	-
Noise Figure (Typ @ f)	3dB @ 200MHz	-	1dB ~ 1.6dB @ 900MHz ~ 1.8GHz	0.5dB ~ 1.45dB @ 150MHz ~ 10GHz	2.4dB @ 1GHz	-
Power - Max	625mW	200mW	580mW	160mW	-	60W
DC Current Gain (hFE) (Min)	40 @ 20mA, 10V	180 @ 5mA, 5V	70 @ 30mA, 8V	160 @ 25mA, 3V	48 @ 10mA, 2V	10 @ 5A, 5V
Current - Collector (Ic) (Max)	100mA	50mA	80mA	45mA	26mA	15A
Operating Temperature	-55°C ~ 150°C	150°C	150°C	150°C	150°C	-
Mounting Type	Through Hole	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Chassis Mount
Package / Case	TO-226-3, TO-92-3	TO-236-3, SC-59, SOT-23-3	SC-101, SOT-883	4-SMD, Flat Leads	SOT-23-6	211-07
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Through-Hole Replacement (Legacy Systems): No direct through-hole equivalent is available among the active substitute parts listed. All active alternatives employ surface mount packaging. Through-hole designs requiring BF959 replacement necessitate circuit board redesign or continued use of remaining BF959 inventory.

For Surface Mount Redesigns (Recommended Path):

BFR193L3E6327XTMA1 (Infineon Technologies) - Recommended for applications requiring voltage ratings closest to the BF959 (12V breakdown voltage). This part provides 8GHz frequency capability, 580mW power dissipation, and 80mA collector current, maintaining compatibility with moderate RF frequency requirements. ROHS3 compliant and active product status ensure long-term availability.

BFP740FESDH6327XTSA1 (Infineon Technologies) - Suitable for high-frequency RF applications requiring 47GHz transition frequency. Voltage rating of 4.7V limits applicability to lower-voltage circuit designs. ROHS3 compliant with active product status.

2SC4713KT146R (Rohm Semiconductor) - Applicable for 800MHz RF applications with reduced voltage requirements (6V breakdown). Power dissipation of 200mW and 50mA collector current represent reduced capability compared to BF959. ROHS3 compliant and active product status.

HFA3134IHZ96 (Intersil) - Dual NPN configuration suitable for balanced RF amplifier designs. 8.5GHz frequency capability and 9V voltage rating provide moderate performance. ROHS3 compliant and active product status.

MRF455 (MACOM Technology Solutions) - Applicable only for high-power RF amplification applications requiring 60W power dissipation and 15A collector current. Chassis mount packaging and 18V voltage rating address power amplifier requirements distinct from BF959 small-signal applications. ROHS3 compliant and active product status.

Compliance Considerations: All substitute parts listed carry ROHS3 compliance and active product status, ensuring regulatory alignment and supply chain continuity. The BF959 is RoHS non-compliant; migration to compliant alternatives is necessary for new designs subject to RoHS regulations.

Frequently Asked Questions (FAQ)

Q: Can the BF959 be directly replaced with a surface mount equivalent?

A: No direct through-hole to surface mount replacement exists among the listed active alternatives. Circuit board redesign is required to accommodate surface mount packages (SOT-23, SOT-883, or 4-TSFP). Alternatively, through-hole adapter boards may be used with surface mount components.

Q: Which substitute part is most suitable for a 700MHz RF amplifier design?

A: The BFR193L3E6327XTMA1 provides the closest performance match for 700MHz operation, offering 8GHz transition frequency, 12V voltage rating, and 580mW power dissipation. The 2SC4713KT146R is also suitable for 800MHz applications with reduced power requirements.

Q: What is the voltage rating limitation when selecting a substitute?

A: The BF959 operates at 20V maximum collector-emitter breakdown voltage. Substitute parts with lower voltage ratings (such as BFP740FESDH6327XTSA1 at 4.7V or 2SC4713KT146R at 6V) are not suitable for circuits designed for 20V operation. The BFR193L3E6327XTMA1 (12V) and HFA3134IHZ96 (9V) provide intermediate voltage capability.

Q: Are all substitute parts RoHS compliant?

A: Yes. All listed substitute parts carry ROHS3 compliance. The original BF959 is RoHS non-compliant. New designs must incorporate compliant alternatives to meet regulatory requirements.

Q: What is the difference between the BFR193L3E6327XTMA1 and BFP740FESDH6327XTSA1?

A: The BFR193L3E6327XTMA1 operates at 12V with 8GHz frequency capability, suitable for moderate-frequency RF applications. The BFP740FESDH6327XTSA1 operates at 4.7V with 47GHz frequency capability, designed for high-frequency microwave applications. Voltage and frequency requirements determine which part is appropriate.

Q: Can the MRF455 replace the BF959 in small-signal RF circuits?

A: No. The MRF455 is a high-power device rated for 60W power dissipation and 15A collector current, designed for power amplification. The BF959 is a small-signal device rated for 625mW. The MRF455 is applicable only to high-power RF amplifier designs.

Q: What packaging considerations apply when selecting a substitute?

A: The BF959 uses through-hole TO-92 packaging. All active substitutes employ surface mount packages: SOT-23-3 (2SC4713KT146R), SOT-883 (BFR193L3E6327XTMA1), 4-TSFP (BFP740FESDH6327XTSA1), SOT-23-6 (HFA3134IHZ96), or chassis mount 211-07 (MRF455). Circuit board redesign is required for surface mount migration.

Q: Is the HFA3134IHZ96 suitable as a direct replacement?

A: The HFA3134IHZ96 is a dual NPN device (two transistors in one package) with 8.5GHz frequency capability and 9V voltage rating. It is suitable for balanced RF amplifier designs but not for single-transistor applications requiring the BF959 pinout configuration.

Q: What is the minimum operating temperature range for substitute parts?

A: The BF959 operates from -55°C to 150°C. Listed substitute parts specify only maximum operating temperature of 150°C without stated minimum temperature. Applications requiring -55°C minimum operation must confirm substitute part specifications with manufacturer datasheets.

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