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

STMicroelectronics MJ802

Name: MJ802
Brand: STMicroelectronics
SKU: MJ802
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MJ802

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-204AA, TO-3

Datasheet:: MJ802.pdf

Description:: TRANS NPN 90V 30A TO-3

Quantity:: RFQ Add To RFQ list

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Inventory:7,475

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Product details

Overview

MJ802 from STMicroelectronics is a silicon NPN epitaxial-base power transistor in a TO-3 metal package, rated for 90 V V_CEO, 30 A I_C, and 200 W P_tot at T_c ≤ 25 °C. It serves as a high-current switching and linear amplifier device in industrial power supplies, motor control stages, and DC-DC converter output stages.

For engineers reviewing the MJ802 datasheet, MJ802 pinout, MJ802 application, or MJ802 equivalent, key selection criteria include junction-to-case thermal resistance (0.875 °C/W), sustained V_CE(sus) under R_BE = 100 Ω (100 V), h_FE range (25–100 at 7.5 A), saturation voltage (0.8 V at I_C = 7.5 A, I_B = 0.75 A), and maximum operating junction temperature (200 °C).

Technical Context

The MJ802 is a ruggedized, discrete NPN bipolar junction transistor optimized for high-power linear and switching operation. Its epitaxial base structure supports stable gain and low saturation voltage across wide current ranges, with specified f_T of 2 MHz enabling moderate-frequency switching up to ~100 kHz in hard-switched topologies.

Designed for mounting on heatsinks via its metal case, it features a single-ended TO-3 configuration with collector-connected case. Absolute maximum ratings include 100 V V_CBO, 4 V V_EBO, and 7.5 A I_B, supporting robust gate/base drive design in high-side or low-side configurations.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	90 V - Maximum safe collector-emitter voltage with base open; defines upper limit for DC bus or flyback clamp applications.
I_C	30 A - Continuous collector current rating at T_c = 25 °C; requires active heatsinking above ~5 A in steady state.
P_tot	200 W - Total power dissipation at case temperature ≤ 25 °C; derates linearly above that temperature per R_thj-case.
R_thj-case	0.875 °C/W - Thermal resistance from junction to case; determines minimum heatsink requirement for given power and allowable T_j.
h_FE	25–100 - DC current gain at I_C = 7.5 A, V_CE = 2 V; informs base drive sizing for saturation in switching use.
V_CE(sat)	0.8 V - Collector-emitter saturation voltage at I_C = 7.5 A, I_B = 0.75 A; directly impacts conduction loss and thermal load.
f_T	2 MHz - Transition frequency at I_C = 1 A, V_CE = 10 V; sets practical upper bound for linear amplification bandwidth.

Pinout & Package

Package: TO-3 metal case with collector internally connected to the case flange. Mounting hole centered, leads arranged in line (Emitter–Base–Collector) when viewed from bottom with tab up.

Pin/Terminal	Circuit Role	Design Meaning
Lead 1 (left)	Emitter	Main current exit path; electrically isolated from case; must be insulated if case is grounded.
Lead 2 (center)	Base	Control terminal requiring ~0.75 A drive for full saturation at 7.5 A collector current.
Lead 3 (right)	Collector	Internally bonded to metal case; primary heat path; must be electrically isolated from PCB unless used as common ground node.

Key Features

Feature	Design Value
High ruggedness rating	200 °C max junction temperature and 100 V V_CBO support operation in harsh industrial environments with transient overvoltage exposure.
Low saturation voltage	V_CE(sat) = 0.8 V at 7.5 A enables <1 W conduction loss per device in medium-duty switching, reducing heatsink size.
Stable h_FE over current range	h_FE remains 25–100 from 1 A to 7.5 A, simplifying base drive design without dynamic compensation.
TO-3 mechanical robustness	Metal case provides superior thermal transfer and mechanical durability versus plastic packages, suitable for high-vibration equipment.

Applications

Industrial DC Motor Drive

Linear Regulator Pass Element

Use Scenario: Used as main switching transistor in 48 V, 20 A brushed DC motor H-bridge half-bridge stage.

IC Role / Device Role / Timing Role: NPN power switch controlling motor current direction and magnitude via PWM base drive.

Use Value: 90 V V_CEO accommodates back-EMF spikes; 0.875 °C/W R_thj-case allows direct mounting to chassis for passive cooling.

Use Scenario: Serves as series pass transistor in adjustable 0–30 V, 10 A lab bench power supply.

IC Role / Device Role / Timing Role: Linear regulator pass element dissipating up to 120 W during worst-case dropout conditions.

Use Value: 200 °C T_j(max) and 200 W P_tot enable extended safe operation under sustained thermal stress without derating.

Switch-Mode Power Supply Output Stage

Welding Equipment Primary Switch

Use Scenario: Low-frequency (≤50 kHz) switching transistor in forward-converter secondary synchronous rectifier replacement.

IC Role / Device Role / Timing Role: Hard-switched NPN switch replacing MOSFET where gate drive complexity or cost is prohibitive.

Use Value: 2 MHz f_T ensures adequate gain margin at 50 kHz; V_CE(sat) minimizes conduction loss in duty-cycle-dominated operation.

Use Scenario: Primary-side switching transistor in capacitor-discharge spot welder delivering 5 kA pulses.

IC Role / Device Role / Timing Role: High-current pulse switch triggered by isolated base driver, handling repetitive 300 µs pulses.

Use Value: 30 A I_C rating and 100 V V_CER(sus) with R_BE = 100 Ω ensure reliable turn-off under high di/dt and inductive kick.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N3055	Lower V_CEO (60 V), lower h_FE (20–70), higher V_CE(sat) (1.1 V @ 4 A), same TO-3 package.	Not suitable for 80+ V bus applications; limited gain margin at high current.	Select when cost sensitivity outweighs voltage headroom and thermal performance requirements.
TIP3055	Same V_CEO (60 V), lower P_tot (90 W), plastic TO-218 package, no metal case thermal path.	Requires larger heatsink; unsuitable for high-reliability or high-temperature ambient designs.	Choose only for non-critical, low-volume, or space-constrained PCB-mount applications where case isolation is not required.

Compared with 2N3055 and TIP3055, the MJ802 delivers higher voltage capability, lower saturation loss, and superior thermal transfer via its metal case-making it preferred for industrial-grade 48–90 V systems demanding long-term reliability under thermal stress.

Availability

MJ802 is available at Aetrix Electronics and suitable for industrial DC motor drives, linear regulator pass stages, and welding equipment primary switching requiring stable component supply and traceable legacy sourcing.

Supply support for MJ802 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The MJ802 belongs to ST's legacy high-power bipolar transistor product line, engineered specifically for ruggedized linear amplification and hard-switching in industrial power conversion and motor control systems.

FAQ

Is the MJ802 still in active production?

No-the MJ802 is marked "Obsolete Product(s)" in the official STMicroelectronics datasheet dated October 2003. It remains available through authorized legacy distributors and Aetrix Electronics' long-term inventory program with full traceability and testing verification per original specification.

Can the MJ802 be used in surface-mount designs?

No-it uses a through-hole TO-3 metal package with three axial leads and requires mechanical mounting to a heatsink. It is incompatible with SMT assembly processes and cannot be reflow soldered or placed by pick-and-place equipment.

What is the recommended base drive circuit for saturation switching?

A current-source base drive delivering ≥0.75 A peak into 1.3 V V_BE(sat) is required for full saturation at I_C = 7.5 A. A Darlington or transformer-coupled driver with ≥1.5 A peak capability ensures margin for h_FE variation and temperature drift.

Does the MJ802 require emitter ballasting resistors in parallel configurations?

Yes-when paralleling multiple MJ802 devices, individual emitter resistors (typically 0.1–0.22 Ω, 2–3 W) are required to ensure current sharing due to h_FE and V_BE mismatches. Without them, thermal runaway may occur under high-current operation.

MJ802 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-204AA, TO-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 30 A

Voltage - Collector Emitter Breakdown (Max):: 90 V

Vce Saturation (Max) @ Ib, Ic:: 800mV @ 750mA, 7.5A

Current - Collector Cutoff (Max):: 1mA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 25 @ 7.5A, 2V

Power - Max:: 200 W

Frequency - Transition:: 2MHz

Operating Temperature:: 200°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Chassis Mount

Supplier Device Package:: TO-3

MJ802 FAQ

1.How can I place an order for MJ802 through Aetrix?

Please submit a Request for Quotation (RFQ) for MJ802 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 MJ802 reliable?

The price and inventory of MJ802 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MJ802 is usually 5 days.

3.What payment methods are accepted for MJ802?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MJ802 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MJ802?

MJ802 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MJ802 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 MJ802?

For technical support, including MJ802 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MJ802 requirements.

6.How does Aetrix verify that MJ802 is sourced from the original manufacturer or authorized distributors?

All MJ802 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 MJ802 meets industry standards.

7.What is the process for return or replacement of MJ802?

All MJ802 units undergo pre-shipment inspection (PSI). If there is an issue with MJ802, 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 MJ802 part is unused and in its original packaging.

Return procedure for MJ802:

1.Submit a request within 90 days.

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

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