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

STMicroelectronics MD1802FX

Name: MD1802FX
Brand: STMicroelectronics
SKU: MD1802FX
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MD1802FX

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: ISOWATT218FX

Datasheet:: MD1802FX.pdf

Description:: TRANS NPN 700V 10A ISOWATT-218FX

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MD1802FX from STMicroelectronics is a high-voltage NPN power transistor in ISOWATT218FX package, designed for horizontal deflection output stages in CRT TVs and switch-mode power supplies. It features 1500 V V_CES, 10 A continuous collector current, 57 W total dissipation at T_c = 25°C, and 2.2 °C/W thermal resistance junction-to-case.

For engineers reviewing the MD1802FX datasheet, MD1802FX pinout, MD1802FX application, or MD1802FX equivalent, key selection criteria include V_CES rating, safe operating area under inductive switching, h_FE consistency at 5A, insulation withstand voltage (2500 V RMS), and thermal derating behavior above 25°C case temperature.

Technical Context

The MD1802FX employs diffused collector planar technology with an enhanced high-voltage structure optimized for horizontal deflection linearity and reliability in CRT TV applications. Its design delivers tight h_FE range (5.5–8.5 at I_C = 5A, V_CE = 5V) and low base-drive requirements (V_BE(sat) = 1.2 V at I_C = 5A, I_B = 1.25A).

It supports pulsed inductive switching with t_s = 2.4 µs and t_f = 0.2 µs under specified test conditions (I_C = 4A, I_B(on) = 500mA, V_BE(off) = −2.7V, f_h = 16 kHz, L_BB(off) = 4.5 µH), and maintains V_CEO(sus) = 700 V at I_C = 100 mA.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CES	1500 V - Maximum collector-emitter blocking voltage with base open, critical for CRT flyback safety margin
I_C	10 A - Continuous collector current rating defining sustained horizontal deflection drive capability
P_TOT	57 W at T_c = 25°C - Thermal power limit requiring heatsink design with ≤2.2 °C/W R_thj-case
V_ins	2500 V RMS - Insulation withstand voltage from all three leads to heatsink, enabling safe chassis-grounded mounting
h_FE	5.5–8.5 at I_C = 5A - Tight DC current gain spread ensures consistent base drive sizing across production lots
t_s/t_f	2.4 µs / 0.2 µs - Storage and fall times measured under standardized inductive switching, directly impacting deflection waveform fidelity
V_CE(sat)	1.5 V at I_C = 5A, I_B = 1.25A - Low saturation voltage minimizes conduction loss and heatsink thermal load

Pinout & Package

Package: ISOWATT218FX - Fully insulated, U.L.-compliant power package with integrated heatsink interface and creepage/clearance optimized for high-voltage CRT applications.

Pin/Terminal	Circuit Role	Design Meaning
1 (Collector)	Main high-voltage current path	Connected to flyback transformer primary; must withstand 1500 V transient spikes during retrace
2 (Base)	Control input for switching	Receives low-current drive signal; requires precise 1.25A peak for full saturation at 5A I_C
3 (Emitter)	Current return path	Common reference for deflection circuit; electrically isolated from heatsink via package insulation

Key Features

Feature	Design Value
Diffused collector "Enhanced generation" structure	Enables stable h_FE and V_CEO(sus) across −65°C to +150°C junction temperature range
Fully insulated ISOWATT218FX package	Eliminates need for insulating washers; allows direct mounting to grounded heatsink with 2500 V RMS isolation
Tight h_FE range at operating current	Reduces base drive circuit variation; simplifies driver stage design for mass-produced CRT TVs
Low V_BE(sat) and V_CE(sat)	Minimizes power loss during conduction phase, improving efficiency and reducing thermal stress on PCB layout
Stable SOA under inductive load	Guarantees reliable operation in horizontal deflection circuits with 4.5 µH reactive load and 16 kHz switching

Applications

Horizontal Deflection Output

Switch-Mode Power Supply

Use Scenario: Horizontal scanning stage in standard-definition CRT television sets, driving flyback transformer primary winding.

IC Role / Device Role / Timing Role: High-voltage NPN power switch controlling retrace timing and energy transfer to EHT generation.

Use Value: 1500 V V_CES and 700 V V_CEO(sus) ensure robustness against flyback voltage overshoot; 2.4 µs storage time preserves linearity of scan waveform.

Use Scenario: Primary-side switching element in offline SMPS for CRT TV main power and auxiliary rails.

IC Role / Device Role / Timing Role: Main power switch in quasi-resonant or fixed-frequency topology, handling 10 A continuous current.

Use Value: 57 W power dissipation rating and 2.2 °C/W R_thj-case enable compact heatsink design; 2500 V insulation supports direct chassis mounting.

High-Voltage Display Driver

Inductive Load Switching

Use Scenario: High-voltage driver in monochrome or color CRT monitor deflection circuits.

IC Role / Device Role / Timing Role: Line-output transistor delivering precise timing-controlled current pulses to deflection yoke.

Use Value: Tight h_FE (5.5–8.5) ensures uniform brightness and geometry across units; low V_BE(sat) reduces base drive power demand.

Use Scenario: Energy-transfer switch in resonant LC networks for CRT EHT generation and focus control.

IC Role / Device Role / Timing Role: Fast-switching NPN transistor managing stored inductive energy release during flyback phase.

Use Value: 0.2 µs fall time and controlled SOA prevent secondary breakdown during rapid turn-off under reactive loads.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BU2520DX	V_CES = 1500 V, I_C = 10 A, but R_thj-case = 2.5 °C/W (vs. 2.2 °C/W); no 2500 V insulation rating	Lacks certified insulation; requires external isolation hardware for chassis-mounted use	Acceptable where heatsink isolation is implemented externally and thermal margin permits higher R_th
2SC5387	V_CES = 1500 V, I_C = 8 A, h_FE min = 4.0 (vs. 5.5); TO-3P package without integrated insulation	Lower current rating and wider h_FE spread increase driver design complexity and reduce SOA margin	Suitable only for lower-power CRT designs with relaxed thermal and gain stability requirements

Compared with BU2520DX and 2SC5387, the MD1802FX provides superior thermal performance (2.2 °C/W), certified 2500 V insulation, and tighter h_FE control-making it uniquely suited for cost-sensitive, high-reliability CRT horizontal deflection stages requiring direct-chassis mounting and minimal driver component count.

Availability

MD1802FX is available at Aetrix Electronics and suitable for CRT television manufacturing, horizontal deflection circuit repair, and legacy display power supply redesign requiring stable component supply and long-term obsolescence management.

Supply support for MD1802FX 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 MD series targets high-voltage power switching in legacy display systems, with the MD1802FX specifically engineered for CRT horizontal deflection stages demanding ruggedness, thermal efficiency, and integrated electrical isolation.

FAQ

What is the maximum allowable case temperature for continuous operation?

The MD1802FX has a maximum junction temperature of 150°C and a thermal resistance of 2.2 °C/W. With a typical heatsink thermal resistance of 1.5 °C/W and ambient temperature of 50°C, the maximum sustainable case temperature is 95°C to maintain T_J ≤ 150°C at full 10 A load. Derating curves in the datasheet specify linear power reduction above 25°C case temperature.

Is the ISOWATT218FX package compatible with standard TO-218 mounting hardware?

Yes-the ISOWATT218FX shares identical mechanical footprint and screw-hole positioning with TO-218, allowing direct replacement in existing fixtures. However, its fully insulated construction eliminates the need for mica washers or silicone pads, enabling safer, lower-thermal-resistance mounting to grounded metal chassis without additional isolation components.

Can MD1802FX be used in modern LCD or LED TV power supplies?

No-it is not recommended. The MD1802FX's 16 kHz switching capability, SOA profile, and drive characteristics are optimized for CRT horizontal deflection waveforms and flyback topologies. Modern switch-mode controllers operate at higher frequencies (60–500 kHz) and require faster switching, lower gate charge, and different safe operating area constraints not supported by this device.

Does MD1802FX meet RoHS and REACH requirements?

Yes-per STMicroelectronics' ECOPACK® documentation, the MD1802FX uses lead-free second-level interconnects and complies with RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. The package marking and inner box label indicate compliance status, and full material declarations are available through ST's official product portal.

MD1802FX Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: ISOWATT218FX

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 10 A

Voltage - Collector Emitter Breakdown (Max):: 700 V

Vce Saturation (Max) @ Ib, Ic:: 1.5V @ 1.25A, 5A

Current - Collector Cutoff (Max):: 200µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 5.5 @ 5A, 5V

Power - Max:: 57 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: ISOWATT-218FX

MD1802FX FAQ

1.How can I place an order for MD1802FX through Aetrix?

Please submit a Request for Quotation (RFQ) for MD1802FX 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 MD1802FX reliable?

The price and inventory of MD1802FX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MD1802FX is usually 5 days.

3.What payment methods are accepted for MD1802FX?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MD1802FX transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MD1802FX?

MD1802FX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MD1802FX 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 MD1802FX?

For technical support, including MD1802FX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MD1802FX requirements.

6.How does Aetrix verify that MD1802FX is sourced from the original manufacturer or authorized distributors?

All MD1802FX 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 MD1802FX meets industry standards.

7.What is the process for return or replacement of MD1802FX?

All MD1802FX units undergo pre-shipment inspection (PSI). If there is an issue with MD1802FX, 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 MD1802FX part is unused and in its original packaging.

Return procedure for MD1802FX:

1.Submit a request within 90 days.

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

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