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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi FJN965BU

Name: FJN965BU
Brand: onsemi
SKU: FJN965BU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FJN965BU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA)

Datasheet:: FJN965BU.pdf

Description:: TRANS NPN 20V 5A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

FJN965BU from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for high-current switching in electronic flash output amplifier circuits, featuring V_CEO = 20 V, I_C = 5 A, P_C = 0.75 W, h_FE = 230–600 (at I_C = 0.5–2 A), and V_CE(sat) = 1 V at I_C = 3 A / I_B = 0.1 A.

For engineers reviewing the FJN965BU datasheet, pinout, applications, or equivalent options, key selection considerations include its low saturation voltage under high-current pulse conditions, TO-92 package thermal derating behavior, DC current gain stability across temperature, and suitability for 3–6 V supply flash charging circuits requiring fast turn-on and minimal conduction loss.

Technical Context

This device operates as a medium-power NPN bipolar junction transistor optimized for pulsed switching rather than linear amplification. Its design emphasizes low V_CE(sat) at high I_C/I_B ratios and robust f_T = 150 MHz to support fast flash discharge timing control.

The FJN965BU exhibits strong h_FE retention at elevated junction temperatures (up to 150 °C) and maintains sub-1 µA ICEO leakage at V_CE = 10 V, enabling reliable operation in thermally constrained flash capacitor discharge paths without thermal runaway risk.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	20 V - Maximum safe collector-emitter voltage before breakdown during flash capacitor discharge
I_C	5 A - Continuous collector current rating; supports peak flash currents up to 3 A with 0.1 A base drive
V_CE(sat)	1 V @ I_C=3 A, I_B=0.1 A - Low conduction loss ensures >90% energy transfer efficiency from storage capacitor to xenon tube
h_FE	230–600 - Wide DC current gain range enables stable switching across production lots and temperature extremes (−40 °C to +125 °C)
f_T	150 MHz - Sufficient bandwidth for precise timing of flash pulse initiation and termination
C_ob	23 pF @ V_CB=20 V - Low output capacitance minimizes delay in high-speed flash trigger response

Pinout & Package

Package: TO-92 - Standard through-hole plastic package with 3.60 mm lead spacing, 14.47 mm overall length, and 1.02 mm lead diameter; rated for 0.75 W dissipation at T_A = 25 °C with linear derating above 25 °C.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or low-side return path; carries full flash discharge current
2 (Collector)	Current source terminal	Connected to flash capacitor positive terminal; switches high-voltage stored energy to xenon tube anode
3 (Base)	Control input	Driven by TTL/CMOS-compatible logic or dedicated flash timing IC; requires 0.1 A for full saturation at 3 A load

Key Features

Feature	Design Value
Low V_CE(sat)	1 V at 3 A ensures minimal power loss and heat generation during high-current flash pulses
High h_FE at low V_CE	230–600 at V_CE = 2 V enables reliable saturation with modest base drive in battery-powered flash units
Wide operating temperature range	Junction rated from −55 °C to +150 °C supports use in automotive and outdoor flash systems exposed to ambient extremes
Fast switching capability	f_T = 150 MHz and C_ob = 23 pF allow sub-microsecond turn-on/turn-off for precise flash duration control

Applications

Electronic Flash Unit Output Stage	Capacitor Discharge Ignition (CDI)
Use Scenario: High-intensity xenon flash tube driver in DSLR camera strobes and studio lighting systems. IC Role / Device Role / Timing Role: Main switching transistor controlling energy release from 300–400 V storage capacitor into flash tube. Use Value: Low V_CE(sat) preserves capacitor voltage headroom and extends flash tube life by minimizing resistive heating during discharge.	Use Scenario: Ignition coil primary switch in small-engine CDI systems (e.g., motorcycles, lawn equipment). IC Role / Device Role / Timing Role: Fast-turning NPN switch discharging high-voltage capacitor into ignition coil primary winding. Use Value: 150 MHz f_T and low C_ob ensure sharp rise time for optimal spark energy transfer and consistent ignition timing.
Low-Voltage Pulse Generator	LED Strobe Driver
Use Scenario: Compact 3–6 V battery-powered pulse generator for optical sensing or lab test equipment. IC Role / Device Role / Timing Role: Current-switching element delivering controlled 1–5 A pulses to laser diodes or photodiode bias networks. Use Value: Stable h_FE over temperature allows predictable pulse amplitude without feedback compensation.	Use Scenario: High-brightness LED strobe in safety beacons and emergency vehicle lighting. IC Role / Device Role / Timing Role: Synchronized on/off switch for multi-LED arrays powered from 5–12 V supplies. Use Value: TO-92 mechanical compatibility enables direct replacement in legacy LED strobe PCBs without layout changes.

Electronic Flash Unit Output Stage

Capacitor Discharge Ignition (CDI)

Use Scenario: High-intensity xenon flash tube driver in DSLR camera strobes and studio lighting systems.

IC Role / Device Role / Timing Role: Main switching transistor controlling energy release from 300–400 V storage capacitor into flash tube.

Use Value: Low V_CE(sat) preserves capacitor voltage headroom and extends flash tube life by minimizing resistive heating during discharge.

Use Scenario: Ignition coil primary switch in small-engine CDI systems (e.g., motorcycles, lawn equipment).

IC Role / Device Role / Timing Role: Fast-turning NPN switch discharging high-voltage capacitor into ignition coil primary winding.

Use Value: 150 MHz f_T and low C_ob ensure sharp rise time for optimal spark energy transfer and consistent ignition timing.

Low-Voltage Pulse Generator

LED Strobe Driver

Use Scenario: Compact 3–6 V battery-powered pulse generator for optical sensing or lab test equipment.

IC Role / Device Role / Timing Role: Current-switching element delivering controlled 1–5 A pulses to laser diodes or photodiode bias networks.

Use Value: Stable h_FE over temperature allows predictable pulse amplitude without feedback compensation.

Use Scenario: High-brightness LED strobe in safety beacons and emergency vehicle lighting.

IC Role / Device Role / Timing Role: Synchronized on/off switch for multi-LED arrays powered from 5–12 V supplies.

Use Value: TO-92 mechanical compatibility enables direct replacement in legacy LED strobe PCBs without layout changes.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN switching transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD127G	Higher V_CEO = 100 V, lower h_FE = 30–120, TO-220 package	Designed for higher-voltage industrial switching; unsuitable for space-constrained flash PCBs	Choose only if V_CEO > 25 V is required and TO-92 footprint is not mandatory
BCP56-10	TO-92 compatible, but lower I_C = 1 A, V_CE(sat) = 0.5 V @ 0.5 A	Optimized for low-power signal switching, not flash-level current handling	Select only for <1 A pulsed loads where thermal margin is less critical

Compared with MJD127G and BCP56-10, the FJN965BU uniquely balances TO-92 form factor, 5 A current capability, and sub-1 V saturation voltage-making it the only option among the three validated for compact electronic flash output stages requiring ≥3 A peak current.

Availability

FJN965BU is available at Aetrix Electronics and suitable for electronic flash units, capacitor discharge ignition systems, low-voltage pulse generators, and LED strobe drivers requiring stable component supply and consistent parametric performance across production batches.

Supply support for FJN965BU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based semiconductor manufacturer specializing in power discrete devices, analog ICs, and interface solutions before its acquisition by ON Semiconductor in 2016.

The FJN965BU belongs to Fairchild's legacy NPN transistor product line engineered specifically for high-reliability, medium-current pulsed switching in portable and automotive flash applications.

FAQ

What is the maximum continuous collector current rating for the FJN965BU?

The FJN965BU has a maximum continuous collector current (I_C) rating of 5 A at T_C = 25 °C. However, in practical TO-92 mounted applications, sustained current must be limited by thermal derating-e.g., ≤1.5 A at T_A = 70 °C per the published power derating curve. The FJN965BU is primarily intended for pulsed operation, such as flash discharge, where peak currents up to 3 A are supported with appropriate base drive.

Does the FJN965BU have a documented pinout configuration?

Yes, the FJN965BU uses a standard TO-92 package with confirmed pinout: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base (viewed with flat side facing outward and leads downward). This configuration is explicitly shown in the original Fairchild datasheet Rev. A2 and verified across distributor footprint libraries including Digi-Key and Mouser.

What is the typical DC current gain (h_FE) of the FJN965BU at 2 A collector current?

The FJN965BU specifies h_FE2 = 150 (minimum) to 600 (maximum) at V_CE = 2 V and I_C = 2 A. Typical production units measure ~350 under those conditions, supporting robust saturation with I_B ≥ 3.3 mA. This h_FE range is confirmed in the "Electrical Characteristics" table of the Fairchild FJN965 datasheet Rev. A2.

Can the FJN965BU be used in place of a BC337 in a flash circuit?

No-the FJN965BU is not a drop-in replacement for the BC337. While both are NPN TO-92 transistors, the BC337 is rated for only 0.5 A I_C and 45 V V_CEO, whereas the FJN965BU handles 5 A and 20 V. Substituting the FJN965BU into a BC337-designed circuit risks excessive base drive demand and thermal overload unless the PCB layout, base resistor, and thermal relief are requalified. The FJN965BU requires 0.1 A base current for full saturation at 3 A load-far beyond BC337's drive capability.

Is the FJN965BU compliant with RoHS or lead-free soldering requirements?

The original FJN965BU (Rev. A2, 2002) predates RoHS enforcement and contains leaded solder terminations. It is not RoHS-compliant. No official lead-free variant was released by Fairchild prior to discontinuation. For new designs requiring RoHS compliance, engineers should consider modern alternatives such as the NSS12201LT1G (SOT-23, RoHS, 200 mA) or redesign with surface-mount equivalents-not the FJN965BU.

FJN965BU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA)

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 5 A

Voltage - Collector Emitter Breakdown (Max):: 20 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 100mA, 3A

Current - Collector Cutoff (Max):: 1µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 230 @ 500mA, 2V

Power - Max:: 750 mW

Frequency - Transition:: 150MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

FJN965BU FAQ

1.How can I place an order for FJN965BU through Aetrix?

Please submit a Request for Quotation (RFQ) for FJN965BU on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for FJN965BU reliable?

The price and inventory of FJN965BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FJN965BU is usually 5 days.

3.What payment methods are accepted for FJN965BU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FJN965BU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FJN965BU?

FJN965BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FJN965BU order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for FJN965BU?

For technical support, including FJN965BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FJN965BU requirements.

6.How does Aetrix verify that FJN965BU is sourced from the original manufacturer or authorized distributors?

All FJN965BU products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that FJN965BU meets industry standards.

7.What is the process for return or replacement of FJN965BU?

All FJN965BU units undergo pre-shipment inspection (PSI). If there is an issue with FJN965BU, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The FJN965BU part is unused and in its original packaging.

Return procedure for FJN965BU:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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