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

onsemi MJE18008

Name: MJE18008
Brand: onsemi
SKU: MJE18008
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MJE18008

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: MJE18008.pdf

Description:: TRANS NPN 450V 8A TO-220

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Product details

Overview

MJE18008 from onsemi is an NPN bipolar power transistor engineered for high-voltage switching in 220 V line-operated switch-mode power supplies and electronic light ballasts. It delivers 8.0 A continuous collector current, sustains 450 V collector-emitter voltage, and achieves fast switching with turn-off time as low as 1.2 µs at 125 °C - enabling efficient, compact SMPS designs.

For engineers reviewing the MJE18008 datasheet, pinout, applications, or equivalent options, key selection criteria include its 450 V V_CEO(sus), low 0.3 V typical V_CE(sat) at 2 A/0.2 A drive, high h_FE (14–34) across operating current range, and TO-220AB package with isolated mounting options for safety-critical AC-line applications.

Technical Context

The MJE18008 employs a state-of-the-art die optimized for hard-switched, high-voltage DC-DC conversion where low base drive loss and absence of current tail during turn-off are critical. Its flat h_FE profile (14–34 at IC = 1–4.5 A, TC = 125 °C) ensures stable gain under thermal stress, while tight parametric distributions support consistent performance across production lots.

Designed specifically for inductive-load switching in off-line SMPS and ballasts, it features robust reverse-bias safe operating area (RBSOA) validated under clamped conditions up to 300 V, and dynamic saturation voltage (V_CE(dsat)) characterized at 1 s and 3 s delays to model real-world thermal transients during repetitive switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO(sus)	450 Vdc - Sustains 450 V under inductive switching with 100 mA test current, enabling direct use in 220 VAC-derived 300–400 VDC bus topologies without snubber oversizing.
I_C (continuous)	8.0 Adc - Supports ≥60 W output in flyback or forward converters with adequate heatsinking; derates linearly at 1.0 W/°C above 25 °C case temperature.
V_CE(sat) (typ)	0.3 V @ IC = 2.0 A, IB = 0.2 A - Minimizes conduction loss and junction heating during on-state, critical for efficiency in high-duty-cycle operation.
t_off (min)	1.2 µs @ TC = 125 °C - Enables >100 kHz switching in resonant or quasi-resonant SMPS while maintaining safe SOA margins under thermal stress.
h_FE range	14–34 @ IC = 1–4.5 A, TC = 125 °C - Provides predictable base drive requirements across load and temperature, simplifying gate driver design for discrete BJT-based controllers.
R_JC	1.0 °C/W - Enables high-power dissipation (125 W @ TC = 25 °C) with modest heatsink thermal resistance, reducing system size and cost vs. higher-R_JC alternatives.
C_ob	100–150 pF @ V_CB = 10 V - Limits capacitive turn-on loss and EMI generation in high-frequency switching, supporting clean zero-voltage transition in optimized layouts.

Pinout & Package

Package: TO-220AB (Case 221A-09), non-isolated, Pb-free. Mounting tab is electrically connected to collector (pins 2 and 4).

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control input requiring ~0.2–0.9 A drive for full saturation; low V_BE(sat) (0.82–1.25 V) reduces driver power loss.
2	Collector	Main high-side switching node; electrically tied to metal tab - requires insulated mounting hardware when referenced to heatsink potential.
3	Emitter	Power return path; low-inductance connection essential to minimize switching overshoot and ensure stable turn-off behavior.
4	Collector	Dual-collector configuration improves current sharing and thermal distribution; enables parallel layout routing for reduced trace inductance.

Key Features

Feature	Design Value
No coil required for turn-off	Eliminates external base-turn-off inductor, reducing BOM count, board space, and failure points in cost-sensitive SMPS designs.
Tight lot-to-lot parametric spread	Ensures consistent switching timing and gain across manufacturing batches - critical for repeatable EMI compliance and thermal management.
High and flat h_FE at 125 °C	Maintains usable current gain under worst-case thermal conditions, avoiding gain collapse and uncontrolled saturation in enclosed or high-ambient environments.
UL-recognized MJF18008 variant available	Provides 3500 V_RMS isolation for safety-certified designs; MJE18008 itself supports non-isolated but thermally robust implementations.
Pb-free and RoHS compliant	Meets global environmental regulations without performance trade-offs - no lead content impact on solderability or reliability.

Applications

Compact Flyback SMPS	Electronic Fluorescent Ballast (EFB)
Use Scenario: 20–60 W offline flyback converter powering LED drivers or auxiliary rails in industrial equipment. IC Role / Device Role / Timing Role: Main switching transistor handling primary-side energy transfer at 65–130 kHz, directly driven by UC384x or similar PWM controller. Use Value: Low V_CE(sat) and fast t_off reduce conduction and switching losses, enabling >85% efficiency without active cooling in sealed enclosures.	Use Scenario: High-frequency (25–60 kHz) electronic ballast driving T5/T8 fluorescent lamps in commercial lighting fixtures. IC Role / Device Role / Timing Role: Half-bridge switching element controlling lamp current waveform; operated in resonant mode with soft turn-on/turn-off. Use Value: Flat h_FE and tight parameter distribution ensure matched switching characteristics between bridge legs, minimizing lamp flicker and acoustic noise.
AC-DC Adapter Primary Switch	DC-DC Boost PFC Stage
Use Scenario: Universal-input (90–264 VAC), 30–45 W adapter for consumer electronics with integrated primary-side regulation. IC Role / Device Role / Timing Role: Primary-side switch in discontinuous conduction mode (DCM) flyback, directly sensing reflected output voltage via auxiliary winding. Use Value: 450 V V_CEO(sus) provides 25% margin over 375 V peak rectified voltage, eliminating need for TVS clamping and improving surge immunity.	Use Scenario: Active boost PFC front-end stage in 100–200 W industrial power supplies, operating in continuous conduction mode (CCM). IC Role / Device Role / Timing Role: High-voltage switch in boost topology, synchronized to line frequency and modulated at 30–100 kHz for power factor correction. Use Value: Robust RBSOA and low C_ob enable reliable operation under high dv/dt and high-current stress during zero-crossing transitions.

Compact Flyback SMPS

Electronic Fluorescent Ballast (EFB)

Use Scenario: 20–60 W offline flyback converter powering LED drivers or auxiliary rails in industrial equipment.

IC Role / Device Role / Timing Role: Main switching transistor handling primary-side energy transfer at 65–130 kHz, directly driven by UC384x or similar PWM controller.

Use Value: Low V_CE(sat) and fast t_off reduce conduction and switching losses, enabling >85% efficiency without active cooling in sealed enclosures.

Use Scenario: High-frequency (25–60 kHz) electronic ballast driving T5/T8 fluorescent lamps in commercial lighting fixtures.

IC Role / Device Role / Timing Role: Half-bridge switching element controlling lamp current waveform; operated in resonant mode with soft turn-on/turn-off.

Use Value: Flat h_FE and tight parameter distribution ensure matched switching characteristics between bridge legs, minimizing lamp flicker and acoustic noise.

AC-DC Adapter Primary Switch

DC-DC Boost PFC Stage

Use Scenario: Universal-input (90–264 VAC), 30–45 W adapter for consumer electronics with integrated primary-side regulation.

IC Role / Device Role / Timing Role: Primary-side switch in discontinuous conduction mode (DCM) flyback, directly sensing reflected output voltage via auxiliary winding.

Use Value: 450 V V_CEO(sus) provides 25% margin over 375 V peak rectified voltage, eliminating need for TVS clamping and improving surge immunity.

Use Scenario: Active boost PFC front-end stage in 100–200 W industrial power supplies, operating in continuous conduction mode (CCM).

IC Role / Device Role / Timing Role: High-voltage switch in boost topology, synchronized to line frequency and modulated at 30–100 kHz for power factor correction.

Use Value: Robust RBSOA and low C_ob enable reliable operation under high dv/dt and high-current stress during zero-crossing transitions.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
STMicroelectronics BUL128D	Lower V_CEO (400 V), higher R_JC (1.5 °C/W), slower t_off (2.0 µs min)	Suitable only for ≤230 VAC inputs; requires larger heatsink and limits max switching frequency to ~60 kHz.	Select when cost sensitivity outweighs efficiency and frequency targets; verify SOA compliance at full load and temperature.
ON Semiconductor MJE13009	Higher I_C (12 A), same V_CEO (450 V), but lower h_FE (8–16) and higher V_CE(sat) (0.5 V typ)	Better for high-current, lower-frequency (<50 kHz) applications; less suitable for high-efficiency, high-frequency SMPS.	Prefer for ruggedized, lower-frequency designs where peak current exceeds 8 A; avoid where base drive loss or thermal headroom is constrained.

Compared with BUL128D and MJE13009, the MJE18008 offers superior combination of high-voltage capability, fast switching, and thermal efficiency - making it optimal for compact, high-frequency, 220 VAC-derived SMPS where conduction loss and thermal management are critical.

Availability

MJE18008 is available at Aetrix Electronics and suitable for switch-mode power supply design, electronic ballast development, and industrial AC-DC conversion requiring stable component supply and long-term manufacturability.

Supply support for MJE18008 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, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The MJE18008 belongs to onsemi's high-voltage bipolar power transistor family, designed specifically for reliability and efficiency in line-operated switching power supplies and lighting control systems.

FAQ

What is the maximum collector-emitter sustaining voltage for the MJE18008?

The MJE18008 has a guaranteed minimum collector-emitter sustaining voltage (V_CEO(sus)) of 450 Vdc at IC = 100 mA and L = 25 mH. This rating is validated under inductive switching conditions and allows safe operation in 220 VAC-derived 300–400 VDC bus applications without additional clamping circuitry. The MJE18008 datasheet confirms this value in the OFF CHARACTERISTICS table.

Is the MJE18008 pin-compatible with the MJF18008?

No - the MJE18008 (TO-220AB, Case 221A) and MJF18008 (TO-220 Fullpak, Case 221D) have different pinouts and isolation structures. MJE18008 uses Style 1 (Base–Collector–Emitter–Collector), while MJF18008 uses Style 2 (Base–Emitter–Collector–Emitter). Their mounting configurations and thermal resistances (R_JC = 1.0 vs. 2.78 °C/W) also differ significantly. The MJE18008 must be used per its specific mechanical outline and layout guidelines.

What is the typical V_CE(sat) of the MJE18008 at elevated temperature?

The MJE18008 exhibits a typical V_CE(sat) of 0.3 V at IC = 2.0 A and IB = 0.2 A, tested at TC = 125 °C. At higher current (IC = 4.5 A, IB = 0.9 A), V_CE(sat) rises to 0.35 V under the same thermal condition. These values are specified in the ELECTRICAL CHARACTERISTICS table and reflect stable on-state performance even under worst-case junction temperature.

Does the MJE18008 require a base turn-off coil?

No - the MJE18008 is explicitly designed to operate without a base turn-off coil. Its "no current tail" characteristic eliminates the need for external inductive turn-off aids, simplifying driver circuitry and improving reliability. This feature is highlighted in the datasheet Features section and confirmed by dynamic saturation voltage measurements showing clean turn-off behavior at 1 s and 3 s delays.

What is the thermal resistance junction-to-case (R_JC) for the MJE18008?

The MJE18008 has a maximum thermal resistance junction-to-case (R_JC) of 1.0 °C/W, measured under standard mounting conditions. This low value enables 125 W total device dissipation at TC = 25 °C and supports effective thermal management in space-constrained power supplies. The value is specified in the THERMAL CHARACTERISTICS table and validated per JEDEC standards.

MJE18008 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: SWITCHMODE™

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 8 A

Voltage - Collector Emitter Breakdown (Max):: 450 V

Vce Saturation (Max) @ Ib, Ic:: 700mV @ 900mA, 4.5V

Current - Collector Cutoff (Max):: 100µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 14 @ 1A, 5V

Power - Max:: 125 W

Frequency - Transition:: 13MHz

Operating Temperature:: -65°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

MJE18008 FAQ

1.How can I place an order for MJE18008 through Aetrix?

Please submit a Request for Quotation (RFQ) for MJE18008 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 MJE18008 reliable?

The price and inventory of MJE18008 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MJE18008 is usually 5 days.

3.What payment methods are accepted for MJE18008?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MJE18008 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MJE18008?

MJE18008 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MJE18008 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 MJE18008?

For technical support, including MJE18008 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MJE18008 requirements.

6.How does Aetrix verify that MJE18008 is sourced from the original manufacturer or authorized distributors?

All MJE18008 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 MJE18008 meets industry standards.

7.What is the process for return or replacement of MJE18008?

All MJE18008 units undergo pre-shipment inspection (PSI). If there is an issue with MJE18008, 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 MJE18008 part is unused and in its original packaging.

Return procedure for MJE18008:

1.Submit a request within 90 days.

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

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