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

onsemi 2N3904RLRAH

Name: 2N3904RLRAH
Brand: onsemi
SKU: 2N3904RLRAH
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N3904RLRAH

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body, Formed Leads

Datasheet:: 2N3904RLRAH.pdf

Description:: TRANS NPN 40V 0.2A TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2N3904RLRAH from onsemi is a general-purpose NPN silicon bipolar junction transistor (BJT) designed for low-power amplification and switching in discrete analog and digital circuits. It features V_CEO = 40 V, I_C = 200 mA continuous, h_FE = 100–300 at I_C = 10 mA, f_T = 300 MHz, and V_CE(sat) ≤ 0.3 V at I_C/I_B = 10 - enabling use in audio preamps, logic-level translators, and small-signal switching in industrial control modules.

For engineers reviewing the 2N3904RLRAH datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain consistency across temperature, low saturation voltage for efficient switching, thermal resistance (R_JA = 200 °C/W), Pb-free/Halide-free compliance, and TO-92 mechanical compatibility with legacy through-hole layouts.

Technical Context

The 2N3904RLRAH operates as a single NPN BJT with fixed emitter-base-collector polarity and no integrated biasing or protection circuitry. Its small-signal h_fe ranges from 100 to 400 at 1 mA, and its f_T of 300 MHz supports RF amplifier stages up to VHF band edges. The device exhibits C_ibo = 8.0 pF and C_obo = 4.0 pF, defining input/output capacitance limits for high-frequency stability.

Thermal design relies on R_JC = 83.3 °C/W and R_JA = 200 °C/W, requiring minimal heatsinking below 150 mW dissipation at 25°C ambient. Its −55°C to +150°C operating junction range supports deployment in automotive under-hood and industrial sensor signal conditioning without derating.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum collector-emitter voltage before breakdown; defines safe operation in 24 V and 36 V supply rail interfaces.
I_C (continuous)	200 mA - Continuous collector current limit; supports driving LEDs, relays, and small MOSFET gates without external current limiting.
h_FE @ 10 mA	100–300 - DC current gain range at mid-current; ensures predictable base drive requirements for saturated switching in logic buffers.
f_T	300 MHz - Transition frequency; enables stable small-signal amplification up to ~100 MHz with proper biasing and layout.
V_CE(sat)	≤ 0.3 V @ I_C/I_B = 10 - Low saturation voltage reduces power loss and heat generation in switching applications.
R_JA	200 °C/W - Junction-to-ambient thermal resistance; determines required PCB copper area for thermal management in sealed enclosures.
Package	TO-92 (Case 29) - Standard through-hole plastic package with 0.1" lead pitch; compatible with automated insertion and wave soldering.

Pinout & Package

2N3904RLRAH uses the industry-standard TO-92 package (Case 29, Style 1), with straight leads and Pb-free/Halide-free construction. Pin 1 is Emitter, Pin 2 is Base, Pin 3 is Collector - verified per onsemi marking diagram and ordering information.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Emitter)	Current exit path for majority carriers	Serves as reference node for bias networks; connects to ground or low-impedance return in common-emitter configurations.
Pin 2 (Base)	Control terminal for minority carrier injection	Requires current-limited drive (typically 1/10th of I_C) to achieve saturation; sensitive to ESD due to thin oxide layer.
Pin 3 (Collector)	Current entry path and output terminal	Connects to load or pull-up resistor; must remain within V_CEO and power dissipation limits during switching transients.

Key Features

Feature	Design Value
Pb-free and Halide-free construction	Complies with RoHS Directive 2011/65/EU and JEDEC JS709B; eliminates brominated flame retardants and lead in soldering processes.
High f_T / low C_obo combination	300 MHz f_T with only 4.0 pF output capacitance enables wideband amplification with minimal neutralization requirements.
Low V_CE(sat) at moderate currents	0.2–0.3 V saturation voltage at I_C = 10–50 mA reduces conduction losses by >60% versus older general-purpose BJTs like 2N2222A.
Stable h_FE over temperature	DC gain remains ≥50 from −55°C to +125°C at I_C = 1 mA, supporting reliable biasing in unregulated environments.
Low noise figure	5.0 dB NF @ I_C = 100 μA, V_CE = 5 V, f = 1 kHz - suitable for microphone preamplifier front-ends and sensor signal conditioning.

Applications

Audio Preamp Stage	Microcontroller GPIO Driver
Use Scenario: Amplifying low-level signals from electret microphones or piezoelectric sensors into ADC input ranges. IC Role / Device Role / Timing Role: Discrete NPN BJT configured in common-emitter topology with emitter degeneration for linearity and gain stability. Use Value: 5.0 dB noise figure and h_fe ≥ 100 at 100 μA enable >60 dB SNR in battery-powered voice recorders without op-amps.	Use Scenario: Level-shifting and current boosting between 3.3 V microcontrollers and 5 V/12 V peripheral loads (e.g., relays, LEDs). IC Role / Device Role / Timing Role: Saturated switch controlled by MCU GPIO, with base resistor selected for I_B ≥ I_C/10. Use Value: V_CE(sat) ≤ 0.3 V ensures <10 mW dissipation at 100 mA load, eliminating need for heatsinking in compact IoT nodes.
Industrial Sensor Interface	Legacy Logic Translator
Use Scenario: Converting 4–20 mA current loop outputs to voltage signals for PLC analog inputs. IC Role / Device Role / Timing Role: Constant-current source or active load in two-transistor current mirror configurations. Use Value: Tight h_FE distribution (100–300) and low I_CBO (<50 nA) ensure <0.1% full-scale error drift over −40°C to +85°C.	Use Scenario: Interfacing TTL/LS logic families (e.g., 74LS00) with modern CMOS microcontrollers operating at 1.8–3.3 V. IC Role / Device Role / Timing Role: Inverting level shifter with pull-up to higher rail and grounded emitter. Use Value: 300 MHz f_T supports clean edge transitions up to 10 MHz, preserving timing margins in mixed-voltage bus systems.

Audio Preamp Stage

Microcontroller GPIO Driver

Use Scenario: Amplifying low-level signals from electret microphones or piezoelectric sensors into ADC input ranges.

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

Use Value: 5.0 dB noise figure and h_fe ≥ 100 at 100 μA enable >60 dB SNR in battery-powered voice recorders without op-amps.

Use Scenario: Level-shifting and current boosting between 3.3 V microcontrollers and 5 V/12 V peripheral loads (e.g., relays, LEDs).

IC Role / Device Role / Timing Role: Saturated switch controlled by MCU GPIO, with base resistor selected for I_B ≥ I_C/10.

Use Value: V_CE(sat) ≤ 0.3 V ensures <10 mW dissipation at 100 mA load, eliminating need for heatsinking in compact IoT nodes.

Industrial Sensor Interface

Legacy Logic Translator

Use Scenario: Converting 4–20 mA current loop outputs to voltage signals for PLC analog inputs.

IC Role / Device Role / Timing Role: Constant-current source or active load in two-transistor current mirror configurations.

Use Value: Tight h_FE distribution (100–300) and low I_CBO (<50 nA) ensure <0.1% full-scale error drift over −40°C to +85°C.

Use Scenario: Interfacing TTL/LS logic families (e.g., 74LS00) with modern CMOS microcontrollers operating at 1.8–3.3 V.

IC Role / Device Role / Timing Role: Inverting level shifter with pull-up to higher rail and grounded emitter.

Use Value: 300 MHz f_T supports clean edge transitions up to 10 MHz, preserving timing margins in mixed-voltage bus systems.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N3904RLRAG	Pb-free but not Halide-free; identical electrical specs and TO-92 packaging.	Acceptable where halogen content is unrestricted (e.g., non-automotive consumer goods).	Select 2N3904RLRAG when RoHS compliance suffices without JIGS/IEC 61249-2-21 halogen restrictions.
MPS2222A	Higher I_C = 600 mA, V_CEO = 40 V, h_FE = 100–300, but larger TO-92 variant (Case 29-12) with different lead spacing.	Preferred for higher-current switching (>200 mA); not drop-in due to mechanical mismatch in automated assembly.	Choose MPS2222A only when increased current handling justifies requalification and footprint adjustment.

Compared with 2N3904RLRAH, 2N3904RLRAG offers identical performance with relaxed halogen compliance, while MPS2222A delivers higher current capability at the cost of non-interchangeable mechanical fit - making 2N3904RLRAH optimal for space-constrained, halogen-free designs requiring precise legacy TO-92 compatibility.

Availability

2N3904RLRAH is available at Aetrix Electronics and suitable for industrial sensor interfaces, audio preamplifiers, and microcontroller GPIO drivers requiring stable component supply, long-term lifecycle assurance, and halogen-free manufacturing compliance.

Supply support for 2N3904RLRAH 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

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

The 2N3904RLRAH belongs to onsemi's legacy general-purpose transistor product line, engineered for reliability, manufacturability, and broad compatibility in cost-sensitive, high-volume discrete circuit designs.

FAQ

What is the maximum continuous collector current rating for the 2N3904RLRAH?

The 2N3904RLRAH has a maximum continuous collector current (I_C) rating of 200 mA at T_A = 25°C. This value decreases linearly above 25°C at 5.0 mW/°C due to thermal derating. At 70°C ambient, usable I_C drops to approximately 178 mA to maintain safe junction temperature. Always verify actual board-level thermal performance using R_JA = 200 °C/W.

Does the 2N3904RLRAH support high-frequency amplification?

Yes, the 2N3904RLRAH supports high-frequency amplification with a transition frequency (f_T) of 300 MHz under standard test conditions (I_C = 10 mA, V_CE = 20 V). Its 4.0 pF output capacitance (C_obo) and 8.0 pF input capacitance (C_ibo) allow stable small-signal gain up to ~100 MHz in properly biased common-emitter configurations with controlled layout parasitics.

Is the 2N3904RLRAH pin-compatible with standard TO-92 footprints?

Yes, the 2N3904RLRAH uses the standard TO-92 package (Case 29, Style 1) with 0.1" lead spacing and Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector - matching legacy 2N3904 variants and enabling direct replacement on existing PCBs without layout changes. Mechanical dimensions align with JEDEC TO-226 specifications.

How does the 2N3904RLRAH differ from the 2N3904G or 2N3904H variants?

The 2N3904RLRAH is Pb-free and Halide-free (per IEC 61249-2-21), whereas 2N3904G is Pb-free only, and 2N3904H is Pb-free/Halide-free but supplied in bulk rather than tape-and-reel. All share identical electrical characteristics and TO-92 packaging, but 2N3904RLRAH is optimized for automated SMT placement via 2000-unit tape-and-reel packaging.

What is the typical noise figure of the 2N3904RLRAH in low-current audio applications?

The 2N3904RLRAH has a typical noise figure (NF) of 5.0 dB at I_C = 100 μA, V_CE = 5.0 V, and f = 1 kHz - measured with R_S = 1.0 kΩ. This makes it well-suited for low-noise, low-power microphone preamplifiers and sensor signal conditioning where minimizing thermal and shot noise is critical to system SNR.

2N3904RLRAH Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body, Formed Leads

Packaging:: Bulk

Product Status:: Active

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 (TO-226)

2N3904RLRAH FAQ

1.How can I place an order for 2N3904RLRAH through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N3904RLRAH 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 2N3904RLRAH reliable?

The price and inventory of 2N3904RLRAH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N3904RLRAH is usually 5 days.

3.What payment methods are accepted for 2N3904RLRAH?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N3904RLRAH transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N3904RLRAH?

2N3904RLRAH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N3904RLRAH 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 2N3904RLRAH?

For technical support, including 2N3904RLRAH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N3904RLRAH requirements.

6.How does Aetrix verify that 2N3904RLRAH is sourced from the original manufacturer or authorized distributors?

All 2N3904RLRAH 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 2N3904RLRAH meets industry standards.

7.What is the process for return or replacement of 2N3904RLRAH?

All 2N3904RLRAH units undergo pre-shipment inspection (PSI). If there is an issue with 2N3904RLRAH, 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 2N3904RLRAH part is unused and in its original packaging.

Return procedure for 2N3904RLRAH:

1.Submit a request within 90 days.

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

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