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

onsemi 2N4401_J61Z

Name: 2N4401_J61Z
Brand: onsemi
SKU: 2N4401_J61Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N4401_J61Z

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2N4401_J61Z.pdf

Description:: TRANS NPN 40V 0.6A TO-92-3

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Product details

Overview

2N4401_J61Z from ON Semiconductor is a TO-92 packaged NPN bipolar junction transistor designed for medium-power amplification and switching applications with 40 V V_CEO, 600 mA I_C, and 625 mW power dissipation at 25°C. It delivers DC current gain (h_FE) from 40 to 300 across 1–500 mA collector current, and supports fast switching with t_on ≤ 400 ns and f_T = 250 MHz - used in relay drivers, LED drivers, and low-frequency signal amplifiers.

For engineers reviewing the 2N4401_J61Z datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO/I_C margin for 24 V control circuits, thermal derating above 25°C, saturation voltage at target drive current, and TO-92 mechanical compatibility with legacy through-hole layouts.

Technical Context

The 2N4401_J61Z operates as a single NPN BJT with fixed emitter-base and collector-base junction structures optimized for linear amplification and hard-switching. Its h_FE variation (40–300) and V_CE(sat) (0.40 V @ 150 mA) reflect process-controlled doping profiles suitable for general-purpose use rather than precision analog or RF operation.

Thermal design relies on its R_θJA = 200°C/W (TO-92 on standard FR-4 PCB), requiring ambient temperature derating beyond 25°C at 5.0 mW/°C. Switching performance is characterized under pulsed conditions (≤300 μs, ≤2% duty cycle), with storage time (t_s = 225 ns) dominating turn-off behavior in saturated switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum safe collector-emitter voltage before breakdown; sets upper limit for 24 V logic-level switching rails.
I_C (max)	600 mA - Continuous collector current rating; supports relay coils up to ~500 mA and LED arrays with series resistors.
P_D (25°C)	625 mW - Total device dissipation at room temperature; requires heatsinking or derating above 25°C (5.0 mW/°C).
h_FE	40–300 - DC current gain range at I_C = 1–500 mA; enables predictable base drive calculation for switch saturation.
f_T	250 MHz - Current gain-bandwidth product; confirms usability up to low-MHz signal amplification but not RF.
V_CE(sat)	0.40 V @ I_C = 150 mA, I_B = 15 mA - Low saturation voltage minimizes power loss and heating in switching mode.
C_cb	6.5 pF @ V_CB = 5 V - Collector-base capacitance affects high-frequency response and Miller effect in amplifier stages.

Pinout & Package

2N4401_J61Z uses the JEDEC TO-92 3-lead through-hole package (straight lead configuration, bulk packing). Pin identification follows standard EBC orientation when viewed with flat side facing outward and leads down: Emitter (pin 1), Base (pin 2), Collector (pin 3).

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current sink terminal	Connected to ground or low-side return path; defines reference for base-emitter bias and current flow direction.
Base (B)	Control input	Receives forward-biased current to enable conduction; requires series resistor to limit I_B per h_FE and load requirements.
Collector (C)	Current source terminal	Connected to load and supply rail; carries full switched current; must be rated for V_CEO and P_D limits.

Key Features

Feature	Design Value
Medium-power switching capability	Supports 600 mA continuous collector current with 0.40 V saturation voltage - reduces conduction loss in 5–24 V control circuits.
Wide h_FE range (40–300)	Enables robust base drive design across production lots without trimming; accommodates both low- and high-gain variants in same footprint.
TO-92 mechanical standardization	Ensures drop-in replacement in legacy through-hole designs and compatibility with automated insertion equipment and hand-soldering workflows.
250 MHz f_T bandwidth	Validates stable small-signal amplification up to ~10 MHz with adequate gain margin - suitable for audio preamps and pulse shaping.
Low-cost general-purpose construction	Manufactured using mature silicon process; delivers consistent parametric distribution and long-term supply stability for cost-sensitive industrial designs.

Applications

Relay Driver Circuits	LED Current Switching
Use Scenario: Driving electromagnetic relays with coil currents of 100–400 mA in industrial PLC output modules and HVAC controllers. IC Role / Device Role / Timing Role: NPN switch operating in saturation mode to connect relay coil to V_CC when base is asserted. Use Value: V_CE(sat) ≤ 0.40 V minimizes power dissipation in the transistor during sustained on-state, reducing thermal stress in enclosed enclosures.	Use Scenario: Switching multi-segment LED displays or high-brightness indicator LEDs in instrumentation panels and automotive dashboards. IC Role / Device Role / Timing Role: Low-side current switch controlling LED anode-to-V_CC paths via emitter-grounded configuration. Use Value: 600 mA I_C rating allows parallel driving of multiple LEDs with shared current-limiting resistors, simplifying BOM count.
DC Motor Speed Control	Signal Amplification Stages
Use Scenario: PWM-based speed control of small brushed DC motors (e.g., fans, actuators) in embedded systems with microcontroller GPIO outputs. IC Role / Device Role / Timing Role: Power switch in low-frequency (<5 kHz) PWM stage, handling peak motor currents up to 500 mA. Use Value: Fast turn-on (t_on ≤ 400 ns) and controlled storage time (t_s = 225 ns) ensure clean PWM edges and minimal shoot-through risk in half-bridge configurations.	Use Scenario: First-stage preamplifier for sensor signals (e.g., thermistor bridges, photodiode transimpedance outputs) in data acquisition front-ends. IC Role / Device Role / Timing Role: Common-emitter amplifier biased for linear operation with I_C = 1–10 mA and V_CE = 5–10 V. Use Value: h_FE ≥ 40 at 1 mA ensures sufficient gain for weak signals, while f_T = 250 MHz provides headroom against bandwidth collapse at higher gains.

Relay Driver Circuits

LED Current Switching

Use Scenario: Driving electromagnetic relays with coil currents of 100–400 mA in industrial PLC output modules and HVAC controllers.

IC Role / Device Role / Timing Role: NPN switch operating in saturation mode to connect relay coil to V_CC when base is asserted.

Use Value: V_CE(sat) ≤ 0.40 V minimizes power dissipation in the transistor during sustained on-state, reducing thermal stress in enclosed enclosures.

Use Scenario: Switching multi-segment LED displays or high-brightness indicator LEDs in instrumentation panels and automotive dashboards.

IC Role / Device Role / Timing Role: Low-side current switch controlling LED anode-to-V_CC paths via emitter-grounded configuration.

Use Value: 600 mA I_C rating allows parallel driving of multiple LEDs with shared current-limiting resistors, simplifying BOM count.

DC Motor Speed Control

Signal Amplification Stages

Use Scenario: PWM-based speed control of small brushed DC motors (e.g., fans, actuators) in embedded systems with microcontroller GPIO outputs.

IC Role / Device Role / Timing Role: Power switch in low-frequency (<5 kHz) PWM stage, handling peak motor currents up to 500 mA.

Use Value: Fast turn-on (t_on ≤ 400 ns) and controlled storage time (t_s = 225 ns) ensure clean PWM edges and minimal shoot-through risk in half-bridge configurations.

Use Scenario: First-stage preamplifier for sensor signals (e.g., thermistor bridges, photodiode transimpedance outputs) in data acquisition front-ends.

IC Role / Device Role / Timing Role: Common-emitter amplifier biased for linear operation with I_C = 1–10 mA and V_CE = 5–10 V.

Use Value: h_FE ≥ 40 at 1 mA ensures sufficient gain for weak signals, while f_T = 250 MHz provides headroom against bandwidth collapse at higher gains.

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
2N2222A	V_CEO = 40 V, I_C = 800 mA, P_D = 500 mW, h_FE = 35–300 - higher current but lower power dissipation and tighter h_FE min.	Preferred where higher peak current is needed but board space limits heat spreading; less margin for sustained 500 mA operation.	Select 2N2222A only if load demands >600 mA pulses and thermal management is enhanced; verify V_CE(sat) at target I_B.
BC547B	V_CEO = 45 V, I_C = 100 mA, P_D = 500 mW, h_FE = 200–450 - lower current rating but higher h_FE consistency and smaller TO-92 variant.	Suitable for low-current signal buffering and low-power logic interfacing; not recommended for >150 mA loads.	Choose BC547B for battery-powered sensor nodes or low-power microcontroller interfaces where gain stability outweighs current capacity.

Compared with 2N4401_J61Z, the 2N2222A offers higher peak current but reduced thermal margin, while the BC547B trades current capability for superior h_FE uniformity and lower drive requirements - selection depends on whether system priority is power handling, thermal robustness, or gain predictability.

Availability

2N4401_J61Z is available at Aetrix Electronics and suitable for relay driver circuits, LED current switching, and DC motor speed control requiring stable component supply and long-term industrial availability.

Supply support for 2N4401_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 is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensors, and logic devices for automotive, industrial, and consumer markets.

The 2N4401_J61Z belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, engineered for reliability, wide parametric distribution tolerance, and compatibility with decades-old through-hole manufacturing infrastructure.

FAQ

What is the maximum collector current rating for the 2N4401_J61Z?

The 2N4401_J61Z has a maximum continuous collector current (I_C) rating of 600 mA at T_A = 25°C. This rating decreases linearly with ambient temperature at 5.0 mW/°C due to its 625 mW power dissipation limit. For reliable operation at elevated temperatures or pulsed loads exceeding 600 mA, consult the Absolute Maximum Ratings table and apply appropriate derating based on PCB thermal design.

Is the 2N4401_J61Z suitable for switching 24 V relay coils?

Yes, the 2N4401_J61Z is commonly used for 24 V relay coil switching. Its 40 V V_CEO rating provides 16 V margin above 24 V nominal supply, and its 0.40 V V_CE(sat) at 150 mA ensures low conduction loss. Ensure base drive delivers sufficient I_B (e.g., ≥15 mA) to maintain saturation, and include a flyback diode across the relay coil to suppress inductive kickback.

Does the 2N4401_J61Z have a documented h_FE range at 500 mA collector current?

Yes, the 2N4401_J61Z datasheet specifies h_FE ≥ 40 at I_C = 500 mA and V_CE = 2.0 V. This minimum gain value enables conservative base resistor calculations for saturated switching applications, ensuring reliable turn-on even at high current and elevated temperature.

What is the thermal resistance from junction to ambient (R_θJA) for the 2N4401_J61Z?

The 2N4401_J61Z has an R_θJA of 200°C/W when mounted on a standard FR-4 PCB (76 mm × 114 mm, 1.57 mm thick) with minimum land pattern. This value assumes natural convection cooling and defines the temperature rise per watt of dissipated power - critical for calculating maximum allowable I_C at non-25°C ambient conditions.

Can the 2N4401_J61Z replace the MMBT4401 in a design?

No, the 2N4401_J61Z cannot directly replace the MMBT4401 without layout changes. While electrically similar, the 2N4401_J61Z uses TO-92 packaging versus the MMBT4401's SOT-23 surface-mount package. The pinouts differ (TO-92: E-B-C; SOT-23: E-B-C but with different physical spacing and solder pad geometry), making them mechanically incompatible despite shared electrical specifications.

2N4401_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):: 600 mA

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

Vce Saturation (Max) @ Ib, Ic:: 750mV @ 50mA, 500mA

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 150mA, 1V

Power - Max:: 625 mW

Frequency - Transition:: 250MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

2N4401_J61Z FAQ

1.How can I place an order for 2N4401_J61Z through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N4401_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 2N4401_J61Z reliable?

The price and inventory of 2N4401_J61Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N4401_J61Z is usually 5 days.

3.What payment methods are accepted for 2N4401_J61Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N4401_J61Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N4401_J61Z?

2N4401_J61Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N4401_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 2N4401_J61Z?

For technical support, including 2N4401_J61Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N4401_J61Z requirements.

6.How does Aetrix verify that 2N4401_J61Z is sourced from the original manufacturer or authorized distributors?

All 2N4401_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 2N4401_J61Z meets industry standards.

7.What is the process for return or replacement of 2N4401_J61Z?

All 2N4401_J61Z units undergo pre-shipment inspection (PSI). If there is an issue with 2N4401_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 2N4401_J61Z part is unused and in its original packaging.

Return procedure for 2N4401_J61Z:

1.Submit a request within 90 days.

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

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