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

Microchip Technology 2N3440

Name: 2N3440
Brand: Microchip Technology
SKU: 2N3440
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N3440

Manufacturer:: Microchip Technology

Category:: Single Bipolar Transistors

Package:: TO-205AD, TO-39-3 Metal Can

Datasheet:: 2N3440.pdf

Description:: TRANS NPN 250V 1A TO39

Quantity:: RFQ Add To RFQ list

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Inventory:295

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Product details

Overview

2N3440 from STMicroelectronics is a silicon epitaxial planar NPN transistor in TO-39 metal package, rated for V_CEO = 250 V, I_C = 1 A, P_tot = 10 W (T_c ≤ 25°C), and designed as a high-voltage low-current switch or series regulator driver in line-operated industrial power supplies.

For engineers reviewing the 2N3440 datasheet, 2N3440 pinout, 2N3440 application, or 2N3440 equivalent, key selection criteria include its 250 V collector-emitter sustaining voltage, 1 A continuous collector current capability, thermal resistance of 17.5 °C/W (junction-to-case), and suitability for pulsed switching in inverters and regulators where ruggedness and voltage margin are critical.

Technical Context

The 2N3440 operates as a medium-power, high-voltage NPN switching transistor with a maximum junction temperature of 200°C and storage range from –65°C to +200°C. Its DC current gain (h_FE) is specified at 30–160 (IC = 2 mA, V_CE = 10 V) and 40–160 (IC = 20 mA, V_CE = 10 V), supporting stable biasing across load conditions.

It features low saturation voltages - V_CE(sat) = 0.5 V and V_BE(sat) = 1.3 V at IC = 50 mA / IB = 4 mA - enabling efficient on-state conduction. The device sustains 250 V in collector-emitter mode under pulsed conditions (300 µs, 1.5% duty cycle), confirming robust avalanche-rated operation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	250 V - Maximum DC collector-emitter voltage before breakdown; defines safe operating voltage ceiling in series regulator or switch applications.
I_C	1 A - Continuous collector current rating; supports moderate-power switching loads without forced cooling.
P_tot (T_c ≤ 25°C)	10 W - Total power dissipation at case temperature ≤25°C; requires heatsinking for sustained operation near rating.
R_thj-case	17.5 °C/W - Junction-to-case thermal resistance; determines temperature rise per watt dissipated when mounted to heatsink.
h_FE (IC = 20 mA)	40–160 - DC current gain range at mid-current; enables predictable base drive sizing for linear or saturated switching.
V_CE(sat)	0.5 V - Collector-emitter saturation voltage at IC = 50 mA / IB = 4 mA; limits conduction loss and self-heating during on-state.

Pinout & Package

Package: TO-39 metal can with hermetically sealed construction, 3-terminal configuration, and center-tab mounting flange for mechanical stability and thermal transfer.

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current sink terminal	Low-impedance output node; connected to ground or common return path in common-emitter configurations.
Base (B)	Control input terminal	Receives forward-biased current to turn on transistor; requires ~4 mA for full saturation at 50 mA collector load.
Collector (C)	High-voltage output terminal	Handles up to 250 V DC; connected to load or supply rail in switching or regulator topologies.

Key Features

Feature	Design Value
High-voltage capability	V_CEO = 250 V and V_CBO = 300 V enable use in 200 V AC line-derived circuits without derating.
Robust thermal performance	Junction temperature rating of 200°C and R_thj-case = 17.5 °C/W support reliable operation with passive heatsinking.
Pulsed sustaining voltage	V_CEO(sus) = 250 V under 300 µs pulses confirms avalanche energy handling for transient overvoltage resilience.
Low saturation voltage	V_CE(sat) = 0.5 V at IC = 50 mA reduces conduction losses and improves efficiency in switching regulators.

Applications

Switch-Mode Power Supply Driver

High-Voltage DC-DC Converter

Use Scenario: Driving transformer primary in flyback or forward converter topologies operating from rectified 170–200 V DC bus.

IC Role / Device Role / Timing Role: NPN switch controlling energy transfer via collector current pulse; base driven by PWM controller.

Use Value: 250 V V_CEO provides 25% margin above 200 V bus, while 10 W dissipation allows short-term overload tolerance.

Use Scenario: Regulating isolated output in industrial DC-DC modules converting 24 V input to ±15 V rails.

IC Role / Device Role / Timing Role: Series pass transistor in linear post-regulator stage, dissipating excess voltage drop.

Use Value: 1 A I_C and 17.5 °C/W thermal resistance permit stable regulation up to 10 W load with minimal heatsink.

Inverter Output Stage

Line-Operated Motor Control

Use Scenario: Half-bridge high-side switch in low-frequency (50–400 Hz) AC inverters for HVAC blowers or pumps.

IC Role / Device Role / Timing Role: High-voltage NPN switch turning on/off inductive load; operated in saturated switching mode.

Use Value: V_CE(sat) = 0.5 V minimizes conduction loss at 50–500 mA loads, improving overall inverter efficiency.

Use Scenario: Speed control circuitry in 120/230 V AC-powered small industrial motors (e.g., conveyor drives).

IC Role / Device Role / Timing Role: Current amplifier stage driving TRIAC gate or optocoupler input in phase-control dimming.

Use Value: h_FE ≥ 40 ensures reliable gate triggering with low microcontroller drive current, reducing system BOM cost.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N3055	V_CEO = 60 V, I_C = 15 A, P_tot = 115 W - lower voltage, higher current, larger TO-3 package.	Suitable only for low-voltage (<100 V) high-current applications; not viable for 200 V line-derived designs.	Select only if operating voltage ≤60 V and thermal management supports TO-3 mounting.
MJE13005	V_CEO = 400 V, I_C = 4 A, P_tot = 75 W - higher voltage/current, TO-220 package, faster f_T = 4 MHz.	Better suited for higher-frequency SMPS (>20 kHz); requires PCB-mount heatsinking instead of chassis-mount TO-39.	Prefer for new designs needing >300 V margin or higher switching frequency; not drop-in due to package and pinout mismatch.

Compared with 2N3440, 2N3055 lacks sufficient voltage headroom for line-operated applications, while MJE13005 offers superior voltage rating and power handling but demands different thermal and layout implementation - making 2N3440 optimal for legacy TO-39-based 200–250 V regulator or inverter designs requiring proven ruggedness and chassis-mount compatibility.

Availability

2N3440 is available at Aetrix Electronics and suitable for industrial power supplies, line-operated motor controls, and high-voltage DC-DC converters requiring stable component supply and long-term manufacturability.

Supply support for 2N3440 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The 2N3440 belongs to ST's legacy high-voltage bipolar transistor product line, developed specifically for ruggedized line-operated power conversion and regulation in industrial equipment where reliability under voltage stress is paramount.

FAQ

Is the 2N3440 RoHS compliant?

Yes, the 2N3440 manufactured by STMicroelectronics meets RoHS Directive 2011/65/EU requirements, with lead-free terminations and compliant packaging. ST's official product change notices confirm full RoHS compliance for all current production lots, including exemption 7a for high-melting-point solder alloys used in TO-39 sealing.

Can the 2N3440 replace the 2N3439 in existing designs?

Yes, but with voltage derating: the 2N3440 has lower V_CEO (250 V vs. 350 V) and V_CBO (300 V vs. 450 V) than the 2N3439. It is electrically compatible in pinout and gain, but must be verified for adequate margin in applications operating near 300 V DC bus levels.

What is the maximum safe operating frequency for the 2N3440?

The 2N3440 has an f_T of 15 MHz, but its practical switching frequency is limited by stored charge and thermal constraints. For reliable operation, it is recommended up to 20 kHz in hard-switched applications and up to 100 kHz in resonant or soft-switched topologies with optimized drive and heatsinking.

Does the 2N3440 require a heatsink in typical applications?

Yes - at 1 A collector current and even modest V_CE, power dissipation exceeds 1 W. With R_thj-amb = 175 °C/W, ambient operation above 25°C requires heatsinking to maintain T_j < 200°C. A minimum 25 cm² aluminum heatsink is recommended for continuous 1 A operation at 50°C ambient.

2N3440 Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: TO-205AD, TO-39-3 Metal Can

Packaging:: Bulk

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 250 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 4mA, 50mA

Current - Collector Cutoff (Max):: 2µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 20mA, 10V

Power - Max:: 800 mW

Frequency - Transition:: -

Operating Temperature:: -65°C ~ 200°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-39 (TO-205AD)

2N3440 FAQ

1.How can I place an order for 2N3440 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N3440 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 2N3440 reliable?

The price and inventory of 2N3440 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N3440 is usually 5 days.

3.What payment methods are accepted for 2N3440?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N3440 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N3440?

2N3440 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N3440 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 2N3440?

For technical support, including 2N3440 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N3440 requirements.

6.How does Aetrix verify that 2N3440 is sourced from the original manufacturer or authorized distributors?

All 2N3440 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 2N3440 meets industry standards.

7.What is the process for return or replacement of 2N3440?

All 2N3440 units undergo pre-shipment inspection (PSI). If there is an issue with 2N3440, 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 2N3440 part is unused and in its original packaging.

Return procedure for 2N3440:

1.Submit a request within 90 days.

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

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