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

onsemi 2N3904_J61Z

Name: 2N3904_J61Z
Brand: onsemi
SKU: 2N3904_J61Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N3904_J61Z

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2N3904_J61Z.pdf

Description:: TRANS NPN 40V 0.2A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2N3904_J61Z from ON Semiconductor is an NPN general-purpose bipolar junction transistor used for amplification and switching in low-power analog and digital circuits, with 40 V V_CEO, 200 mA I_C, 300 MHz f_T, and TO-92 package - deployed in signal conditioning stages of sensor interfaces and discrete logic level translators.

For engineers reviewing the 2N3904_J61Z datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, thermal behavior, switching timing, noise performance, and real-world use context - all aligned to Fairchild/ON Semiconductor Rev. 1.1.0 documentation.

Technical Context

The 2N3904_J61Z operates as a silicon NPN BJT with fixed emitter-base and collector-base junctions optimized for linear amplification up to 100 MHz and saturated switching at ≤100 mA. Its h_FE ranges from 40 (I_C = 0.1 mA) to 300 (I_C = 10 mA), supporting bias-stable Class-A amplifier designs and robust digital gate drive.

Thermal design relies on its 200°C/W R_θJA (TO-92), 625 mW P_D at 25°C, and 5.0 mW/°C derating - requiring minimal heatsinking in ambient-temperature PCB layouts. Switching is characterized by 35 ns t_d/t_r, 200 ns t_s, and 50 ns t_f under standard 10 mA/1 mA drive conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum safe collector-emitter voltage before breakdown; defines rail headroom in low-voltage switch/amplifier stages.
I_C (max)	200 mA - Continuous collector current limit; supports moderate-signal switching (e.g., relay drivers, LED arrays) without thermal runaway.
f_T	300 MHz - Unity-gain bandwidth; enables RF preamp use up to ~30 MHz with usable gain and stable phase margin.
h_FE @ 10 mA	100–300 - DC current gain range at typical bias; ensures predictable base drive sizing for saturation in logic-level interfacing.
V_CE(sat)	0.2 V @ I_C=10 mA/I_B=1 mA - Low saturation voltage reduces conduction loss in switching applications like PWM dimming.
NF	5.0 dB @ 100 μA, 1 kHz–15.7 kHz - Measured noise figure; suitable for low-noise audio preamplifiers and sensor front-ends.
R_θJA	200°C/W - Junction-to-ambient thermal resistance (TO-92); dictates maximum power dissipation at elevated ambient temperatures.

Pinout & Package

2N3904_J61Z is housed in a through-hole TO-92 3-lead package with EBC (Emitter-Base-Collector) pin configuration, standardized per JEDEC TO-92 outline. Lead spacing and body dimensions support manual soldering and wave-solder compatibility on 1.6 mm FR-4 boards.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Reference node for bias network; connects to ground or low-impedance return path in common-emitter configurations.
2 (Base)	Control input	Receives current-limited drive to modulate collector current; requires series resistor to prevent overdrive and thermal stress.
3 (Collector)	Current source terminal	Delivers amplified/saturated output; ties to positive rail via load resistor or active pull-up in switching topologies.

Key Features

Feature	Design Value
High f_T / low C_obo	300 MHz gain-bandwidth with only 4.0 pF output capacitance - preserves signal integrity in wideband amplifiers and fast-switching nodes.
Low V_BE(sat)	0.65–0.85 V @ I_C=10 mA - Enables reliable turn-on from 3.3 V or 5 V microcontroller GPIOs without level-shifting.
Wide h_FE range	40–300 across I_C = 0.1–100 mA - Supports both high-gain small-signal amplification and stable low-gain switching operation.
Low noise figure	5.0 dB at audio frequencies - meets requirements for microphone preamps and precision instrumentation front-ends.
Robust thermal rating	−55°C to +150°C operating range - sustains functionality in industrial control enclosures and automotive under-hood environments.

Applications

Audio Signal Amplification	Sensor Interface Conditioning
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in portable voice recorders. IC Role / Device Role / Timing Role: Discrete NPN amplifier in common-emitter topology with emitter degeneration for linearity and gain stability. Use Value: 5.0 dB noise figure and 300 MHz f_T preserve SNR and bandwidth across 20 Hz–20 kHz audio band without op-amp complexity.	Use Scenario: Converting low-current photodiode or thermistor outputs into clean voltage levels for ADC sampling. IC Role / Device Role / Timing Role: Transimpedance or current-buffer stage providing gain and isolation between passive sensor and MCU input. Use Value: 100–300 h_FE at 100 μA–1 mA enables precise current-to-voltage conversion with minimal loading error.
Digital Logic Level Translation	Low-Power Switching Load Driver
Use Scenario: Interfacing 3.3 V FPGA I/O to 5 V legacy peripherals in mixed-voltage embedded systems. IC Role / Device Role / Timing Role: Active-low NPN inverter with pull-up resistor, translating logic states while isolating voltage domains. Use Value: 35 ns t_d/t_r and 0.2 V V_CE(sat) ensure sub-100 ns propagation delay and <100 mV dropout at 10 mA loads.	Use Scenario: Driving indicator LEDs, small relays, or buzzer elements from microcontroller GPIO pins. IC Role / Device Role / Timing Role: Saturated switch controlling current flow to external loads with minimal power loss. Use Value: 200 mA I_C rating and 0.2 V saturation voltage allow direct drive of 20 mA LEDs or 100 Ω coils without external driver ICs.

Audio Signal Amplification

Sensor Interface Conditioning

Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in portable voice recorders.

IC Role / Device Role / Timing Role: Discrete NPN amplifier in common-emitter topology with emitter degeneration for linearity and gain stability.

Use Value: 5.0 dB noise figure and 300 MHz f_T preserve SNR and bandwidth across 20 Hz–20 kHz audio band without op-amp complexity.

Use Scenario: Converting low-current photodiode or thermistor outputs into clean voltage levels for ADC sampling.

IC Role / Device Role / Timing Role: Transimpedance or current-buffer stage providing gain and isolation between passive sensor and MCU input.

Use Value: 100–300 h_FE at 100 μA–1 mA enables precise current-to-voltage conversion with minimal loading error.

Digital Logic Level Translation

Low-Power Switching Load Driver

Use Scenario: Interfacing 3.3 V FPGA I/O to 5 V legacy peripherals in mixed-voltage embedded systems.

IC Role / Device Role / Timing Role: Active-low NPN inverter with pull-up resistor, translating logic states while isolating voltage domains.

Use Value: 35 ns t_d/t_r and 0.2 V V_CE(sat) ensure sub-100 ns propagation delay and <100 mV dropout at 10 mA loads.

Use Scenario: Driving indicator LEDs, small relays, or buzzer elements from microcontroller GPIO pins.

IC Role / Device Role / Timing Role: Saturated switch controlling current flow to external loads with minimal power loss.

Use Value: 200 mA I_C rating and 0.2 V saturation voltage allow direct drive of 20 mA LEDs or 100 Ω coils without external driver ICs.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT3904	SOT-23 surface-mount package; 350 mW P_D; 357°C/W R_θJA; identical electrical specs except lower power handling.	Preferred for space-constrained PCBs and automated assembly; unsuitable for >150 mW continuous dissipation.	Select MMBT3904 when board area and reflow compatibility outweigh thermal margin needs.
PZT3904	SOT-223 package; 1000 mW P_D; 125°C/W R_θJA; same V_CEO/I_C/f_T, but higher thermal capacity and 4-pin layout (collector tab).	Used where sustained >300 mW dissipation or improved thermal coupling to heatsink is required.	Choose PZT3904 for high-duty-cycle switching or ambient temperatures exceeding 70°C.

Compared with MMBT3904 and PZT3904, the 2N3904_J61Z offers optimal balance of manufacturability, thermal headroom, and legacy design compatibility - especially where through-hole assembly, serviceability, or proven reliability in TO-92 form factor is prioritized.

Availability

2N3904_J61Z is available at Aetrix Electronics and suitable for audio preamplification, sensor signal conditioning, logic level translation, and low-power switching applications requiring stable component supply and long-term obsolescence resilience.

Supply support for 2N3904_J61Z 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor solutions, specializing in power management, analog, sensing, and discrete devices for industrial, automotive, and consumer markets.

The 2N3904_J61Z belongs to ON Semiconductor's legacy general-purpose BJT product line, engineered for broad compatibility, ease of use, and reliability in cost-sensitive analog and digital interface circuits.

FAQ

What is the absolute maximum collector-emitter voltage for 2N3904_J61Z?

The absolute maximum collector-emitter voltage (V_CEO) for 2N3904_J61Z is 40 V at T_A = 25°C. Exceeding this rating risks permanent junction breakdown. Derating is not specified beyond temperature limits, so operation above 40 V - even briefly - is prohibited. This value is confirmed in the Absolute Maximum Ratings table of the Fairchild/ON Semiconductor Rev. 1.1.0 datasheet.

Does 2N3904_J61Z support high-frequency amplification?

Yes, 2N3904_J61Z supports high-frequency amplification with a current gain–bandwidth product (f_T) of 300 MHz at I_C = 10 mA and V_CE = 20 V. It maintains usable gain up to ~30 MHz in common-emitter configurations and is commonly used in RF preamplifiers, oscillator buffers, and broadband signal conditioning - provided layout parasitics and bias stability are controlled.

What is the typical DC current gain (h_FE) of 2N3904_J61Z at 10 mA collector current?

The typical DC current gain (h_FE) of 2N3904_J61Z at I_C = 10 mA and V_CE = 1.0 V is 100–300, as specified in the Electrical Characteristics table. This wide range reflects process variation and supports flexible bias design - e.g., 100 h_FE for conservative saturation drive, 300 h_FE for high-gain small-signal stages. Designers should verify actual gain in circuit using worst-case min/max values.

Can 2N3904_J61Z be used as a switch in digital circuits?

Yes, 2N3904_J61Z is widely used as a saturated switch in digital circuits, with verified performance at I_C = 10 mA / I_B = 1 mA (V_CE(sat) = 0.2 V) and I_C = 50 mA / I_B = 5 mA (V_CE(sat) = 0.3 V). Its 35 ns delay/rise time and 50 ns fall time enable reliable operation up to 5 MHz square-wave switching, making it suitable for GPIO-driven LED control, relay actuation, and level translation.

What package type does 2N3904_J61Z use, and how is it mounted?

2N3904_J61Z uses the TO-92 3-lead through-hole package with EBC pinout (Emitter–Base–Collector). It is mounted vertically on FR-4 PCBs with leads inserted and soldered; thermal performance assumes a 1.6 inch × 1.6 inch × 0.06 inch board per datasheet test condition. The package supports manual assembly, wave soldering, and field-replaceable repair - unlike SMT variants such as MMBT3904.

2N3904_J61Z Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 200 mA

Voltage - Collector Emitter Breakdown (Max):: 40 V

Vce Saturation (Max) @ Ib, Ic:: 300mV @ 5mA, 50mA

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 10mA, 1V

Power - Max:: 625 mW

Frequency - Transition:: 300MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

2N3904_J61Z FAQ

1.How can I place an order for 2N3904_J61Z through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N3904_J61Z 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 2N3904_J61Z reliable?

The price and inventory of 2N3904_J61Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N3904_J61Z is usually 5 days.

3.What payment methods are accepted for 2N3904_J61Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N3904_J61Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N3904_J61Z?

2N3904_J61Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N3904_J61Z 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 2N3904_J61Z?

For technical support, including 2N3904_J61Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N3904_J61Z requirements.

6.How does Aetrix verify that 2N3904_J61Z is sourced from the original manufacturer or authorized distributors?

All 2N3904_J61Z 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 2N3904_J61Z meets industry standards.

7.What is the process for return or replacement of 2N3904_J61Z?

All 2N3904_J61Z units undergo pre-shipment inspection (PSI). If there is an issue with 2N3904_J61Z, 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 2N3904_J61Z part is unused and in its original packaging.

Return procedure for 2N3904_J61Z:

1.Submit a request within 90 days.

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

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