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

STMicroelectronics MJE350

Name: MJE350
Brand: STMicroelectronics
SKU: MJE350
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MJE350

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: MJE350.pdf

Description:: TRANS PNP 300V 0.5A SOT-32-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MJE350 from STMicroelectronics is a complementary silicon PNP power transistor designed for medium-power linear and switching applications in industrial equipment. It features V_CEO = 300 V, I_C = 0.5 A, P_TOT = 20.8 W at T_C ≤ 25 °C, R_thJC = 6.0 °C/W, and h_FE = 30–240 (I_C = 50 mA, V_CE = 10 V), commonly used in high-voltage amplifier stages and relay drivers.

For engineers reviewing the MJE350 datasheet, MJE350 pinout, MJE350 application, or MJE350 equivalent, key selection considerations include its PNP polarity, TO-126 (SOT-32) package thermal performance, negative voltage/current rating convention, and complementary pairing with MJE340 in push-pull output stages.

Technical Context

The MJE350 operates as a medium-power PNP bipolar junction transistor with planar silicon construction. Its absolute maximum ratings specify negative polarity for all voltage and current parameters-e.g., V_CBO = –300 V, V_CEO = –300 V, I_C = –0.5 A-consistent with PNP device conventions.

Electrical behavior is characterized at T_case = 25 °C, with V_BE(on) = –1 V (I_C = –50 mA, V_CE = –10 V), V_CE(sat) = –0.5 V (I_C = –100 mA, I_B = –10 mA), and I_CBO ≤ –100 µA (V_CB = –300 V), supporting stable operation in high-voltage DC bias networks.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	–300 V: Maximum collector-emitter blocking voltage under open-base condition, enabling use in 240 VAC line-connected circuits.
I_C	–0.5 A: Continuous collector current rating, suitable for driving relays, solenoids, or medium-current output stages.
P_TOT	20.8 W at T_C ≤ 25 °C: Total power dissipation limit requiring heatsinking above ~10 W ambient operation.
R_thJC	6.0 °C/W: Junction-to-case thermal resistance, defining minimum heatsink requirement for sustained 15 W operation.
h_FE	30–240 at I_C = –50 mA, V_CE = –10 V: DC current gain range supporting base drive design with margin for temperature variation.
V_CE(sat)	–0.5 V at I_C = –100 mA, I_B = –10 mA: Low saturation voltage minimizes conduction loss in switching mode.

Pinout & Package

Package: SOT-32 (TO-126) - three-terminal plastic power package with metal tab connected to collector, optimized for vertical mounting and heatsink attachment.

Pin/Terminal	Circuit Role	Design Meaning
Collector (Tab)	Main current sink terminal	Electrically connected to metal mounting tab; must be isolated from heatsink unless circuit ground reference permits.
Base	Control input	Receives negative base current to turn on PNP; requires current-limiting resistor in series with control source.
Emitter	Current source terminal	Connected to positive rail in common-emitter configuration; defines reference for V_BE and load return path.

Key Features

Feature	Design Value
Complementary pairing	Matched electrical specs with MJE340 NPN for symmetrical push-pull amplifier and driver designs.
High V_CEO rating	–300 V enables direct interface with 240 VAC rectified rails without additional voltage division.
Low V_CE(sat)	–0.5 V at rated I_C/I_B reduces power loss and self-heating in switching applications.
TO-126 mechanical standard	Industry-standard footprint and mounting hole pattern ensures compatibility with legacy PCB layouts and heatsinks.

Applications

Industrial Relay Drivers

Linear Power Supply Pass Transistors

Use Scenario: Driving 24–48 VDC industrial relays with coil currents up to 400 mA in PLC output modules.

IC Role / Device Role / Timing Role: PNP switch controlling relay coil current path from positive rail to ground.

Use Value: High V_CEO prevents breakdown during inductive kickback; low V_CE(sat) limits heat generation during continuous hold state.

Use Scenario: Series pass element in adjustable 0–30 V, 0.5 A bench power supplies.

IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output voltage via feedback loop.

Use Value: 20.8 W dissipation capacity supports full-load operation at 30 V dropout with adequate heatsinking.

High-Voltage Amplifier Stages

Complementary Push-Pull Output Stages

Use Scenario: Output stage in audio or instrumentation amplifiers operating from ±15 V to ±30 V rails.

IC Role / Device Role / Timing Role: PNP emitter-follower or common-emitter gain stage handling high-voltage signal swing.

Use Value: 150 °C max junction temperature and 6.0 °C/W R_thJC support reliable operation under dynamic thermal loads.

Use Scenario: Complementary pair with MJE340 in Class AB audio output stages or motor H-bridge pre-drivers.

IC Role / Device Role / Timing Role: PNP half of symmetrical output stage delivering current to load during negative half-cycle.

Use Value: Matched h_FE, V_CE(sat), and thermal characteristics minimize crossover distortion and thermal imbalance.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BD140	V_CEO = –80 V, I_C = –1.5 A, P_TOT = 12.5 W	Lower voltage rating but higher current; unsuitable for >100 V circuits	Select when lower voltage, higher current drive is needed and heatsink area is constrained.
TIP2955	V_CEO = –100 V, I_C = –15 A, P_TOT = 115 W, TO-3 package	Higher power, larger package; requires different mounting and layout	Choose for high-current, high-reliability industrial controls where TO-126 thermal limits are exceeded.

Compared with BD140 and TIP2955, the MJE350 uniquely balances 300 V blocking capability with TO-126 form factor and 20.8 W dissipation-making it optimal for space-constrained, high-voltage industrial switching where neither lower-voltage nor TO-3 alternatives fit mechanically or electrically.

Availability

MJE350 is available at Aetrix Electronics and suitable for industrial relay drivers, linear power supply pass elements, high-voltage amplifier stages, and complementary push-pull output stages requiring stable component supply and long-term manufacturability.

Supply support for MJE350 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, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs and discrete devices for industrial, automotive, and consumer markets.

The MJE350 belongs to ST's legacy silicon power transistor family, engineered specifically for robust, cost-effective medium-power linear and switching functions in industrial control and power conversion systems.

FAQ

What is the correct pinout orientation for MJE350 in TO-126 package?

When viewing the flat side of the TO-126 package with leads pointing downward, the left-to-right pin order is Emitter–Base–Collector (E-B-C). The metal tab is the Collector and must be electrically isolated from the heatsink unless circuit topology permits direct connection.

Can MJE350 be used as a direct replacement for MJE340 in a circuit?

No-MJE350 is a PNP device while MJE340 is NPN. They are complementary, not interchangeable. Swapping them without inverting biasing and signal polarity will prevent proper operation and may cause damage due to reversed voltage polarities.

What is the meaning of negative parameter values in MJE350 datasheet tables?

Negative values reflect PNP device convention: V_CEO = –300 V means the collector must be at least 300 V more negative than the emitter to avoid breakdown; I_C = –0.5 A indicates conventional current flows into the emitter and out of the collector.

Does MJE350 require a heatsink in typical switching applications?

Yes-when dissipating >5 W continuously, a heatsink is required. With R_thJC = 6.0 °C/W and max T_J = 150 °C, even at 25 °C ambient, 20.8 W operation demands R_thCA ≤ 12.2 °C/W total thermal resistance, necessitating a heatsink for reliability.

MJE350 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Tube

Product Status:: Active

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 300 V

Vce Saturation (Max) @ Ib, Ic:: -

Current - Collector Cutoff (Max):: 100µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 30 @ 50mA, 10V

Power - Max:: 20.8 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: SOT-32-3

MJE350 FAQ

1.How can I place an order for MJE350 through Aetrix?

Please submit a Request for Quotation (RFQ) for MJE350 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 MJE350 reliable?

The price and inventory of MJE350 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MJE350 is usually 5 days.

3.What payment methods are accepted for MJE350?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MJE350 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MJE350?

MJE350 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MJE350 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 MJE350?

For technical support, including MJE350 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MJE350 requirements.

6.How does Aetrix verify that MJE350 is sourced from the original manufacturer or authorized distributors?

All MJE350 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 MJE350 meets industry standards.

7.What is the process for return or replacement of MJE350?

All MJE350 units undergo pre-shipment inspection (PSI). If there is an issue with MJE350, 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 MJE350 part is unused and in its original packaging.

Return procedure for MJE350:

1.Submit a request within 90 days.

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

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