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

STMicroelectronics HD1520FX

Name: HD1520FX
Brand: STMicroelectronics
SKU: HD1520FX
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: HD1520FX

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: ISOWATT218FX

Datasheet:: HD1520FX.pdf

Description:: TRANS NPN 700V 15A ISOWATT-218FX

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Product details

Overview

HD1520FX from STMicroelectronics is a high-voltage NPN power transistor designed for horizontal deflection in high-definition CRT displays, featuring V_CEO = 700 V, I_C = 15 A, P_tot = 64 W at T_C = 25 °C, and U.L.-compliant ISOWATT218FX insulated package for safe heatsink mounting in 100 Hz color TV systems.

For engineers reviewing the HD1520FX datasheet, HD1520FX pinout, HD1520FX application, or HD1520FX equivalent, key selection criteria include sustained collector-emitter voltage under inductive flyback (V_CE(sus) = 700 V), low saturation voltage (V_CE(sat) = 3 V @ 9 A/1.8 A), thermal resistance (R_thj-case = 1.95 °C/W), and insulation withstand (V_ins = 2500 V RMS).

Technical Context

This device implements Diffused Collector Planar technology with Enhanced High Voltage Structure (EHVS1), enabling stable operation across wide temperature ranges and relaxed drive conditions in CRT horizontal output stages. Its fully insulated ISOWATT218FX package isolates all three leads from the heatsink, eliminating need for insulating washers while maintaining 2500 V RMS insulation.

The transistor supports pulsed inductive switching with t_s = 3.2 µs and t_f = 220 ns under defined load conditions (L_BB(on) = 1.9 µH, V_CE(fly) = 1040 V), and delivers h_FE = 5.5–9.5 at I_C = 9 A, ensuring reliable turn-on/turn-off control in high-frequency deflection circuits.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	700 V - Sustained collector-emitter blocking voltage with base open, critical for flyback energy handling in CRT deflection.
I_C	15 A - Continuous collector current rating, defining maximum steady-state horizontal scan current capability.
P_tot	64 W at T_C = 25 °C - Total power dissipation limit, directly constraining heatsink sizing and thermal design margin.
R_thj-case	1.95 °C/W - Junction-to-case thermal resistance, enabling precise junction temperature calculation from case temperature measurement.
V_ins	2500 V RMS - Insulation withstand voltage from all three leads to external heatsink, satisfying U.L. safety requirements.
V_CE(sat)	3 V @ I_C = 9 A, I_B = 1.8 A - Low saturation voltage minimizes conduction loss and heat generation during active scan period.
h_FE	5.5–9.5 @ I_C = 9 A - DC current gain range determines required base drive current for full saturation in switching applications.

Pinout & Package

HD1520FX uses the ISOWATT218FX package: a fully insulated, stud-mount power package with integrated ceramic isolation, 5.6 g typical weight, and mechanical dimensions compliant with ST's specification (e.g., L4 = 43.2–44.4 mm, G = 10.3–11.5 mm). Mounting torque must not exceed 1 Nm.

Pin/Terminal	Circuit Role	Design Meaning
Collector (C)	Main high-current output terminal	Connected to deflection yoke and flyback transformer primary; carries peak horizontal scan current up to 22 A.
Emitter (E)	Current return path and reference node	Directly tied to ground plane; forms low-impedance return for deflection current and base drive loop.
Base (B)	Control input for switching	Receives TTL-compatible or transformer-coupled drive signal to switch collector current on/off at ~31 kHz.

Key Features

Feature	Design Value
Enhanced High Voltage Structure (EHVS1)	Enables stable 700 V V_CEO operation with reduced sensitivity to temperature drift in CRT deflection loads.
Fully insulated ISOWATT218FX package	Eliminates need for external insulating hardware while providing 2500 V RMS lead-to-heatsink isolation.
Low V_CE(sat) of 3 V	Reduces conduction losses by >30% vs. legacy HV transistors, lowering thermal stress in compact TV chassis.
High I_CM = 22 A	Supports transient surge currents during linearity correction and retrace intervals without secondary breakdown.
Diffused Collector Planar process	Improves silicon efficiency and ruggedness for long-term reliability in high-duty-cycle horizontal output stages.

Applications

Large-Screen CRT TVs

Flat-Panel CRT Monitors

Use Scenario: Horizontal deflection stage in 100 Hz interlaced color television sets with screen diagonals ≥29 inches.

IC Role / Device Role / Timing Role: Switching transistor controlling flyback transformer primary current to generate high-voltage EHT and linearity-corrected scan waveform.

Use Value: V_CEO(sus) = 700 V and V_ins = 2500 V RMS ensure safe operation under worst-case flyback overshoot and chassis-ground leakage conditions.

Use Scenario: Horizontal output circuit in professional broadcast-grade CRT monitors requiring stable 31.25 kHz deflection timing.

IC Role / Device Role / Timing Role: High-current, high-voltage switch synchronizing electron beam sweep across flat-faced phosphor surface with minimal geometric distortion.

Use Value: R_thj-case = 1.95 °C/W and P_tot = 64 W enable continuous operation at elevated ambient temperatures inside sealed monitor enclosures.

HD CRT Projection Systems

Legacy Broadcast Equipment

Use Scenario: Deflection driver in three-tube CRT projection TVs where each tube requires independent horizontal scanning.

IC Role / Device Role / Timing Role: Primary power switch delivering synchronized 31.25 kHz current pulses to individual red/green/blue yoke windings.

Use Value: I_CM = 22 A and t_s/t_f = 3.2 µs/220 ns support fast, repeatable switching across multiple parallel deflection paths.

Use Scenario: Replacement part in field-serviceable analog broadcast transmitters and test equipment using CRT-based waveform displays.

IC Role / Device Role / Timing Role: Drop-in compatible horizontal output transistor maintaining original timing integrity and EHT regulation in aging infrastructure.

Use Value: Pinout and thermal footprint match legacy ST HD-series devices, enabling direct PCB-level replacement without layout modification.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BU2520DX	V_CEO = 1000 V, I_C = 12 A, R_thj-case = 2.2 °C/W, same ISOWATT218FX package	Higher voltage rating but lower current and higher thermal resistance	Preferred where flyback overshoot exceeds 700 V but average current demand is ≤12 A.
2SC5148	V_CEO = 1500 V, I_C = 10 A, non-insulated TO-3P package, no V_ins rating	Requires external insulation hardware; lacks U.L. compliance out-of-box	Used only when cost constraints outweigh safety certification requirements and heatsink isolation can be engineered externally.

Compared with BU2520DX and 2SC5148, HD1520FX offers optimal balance of voltage margin (700 V), current capacity (15 A), and certified insulation (2500 V RMS) for production-grade 100 Hz CRT TVs-making it the preferred choice where regulatory compliance and thermal headroom are jointly critical.

Availability

HD1520FX is available at Aetrix Electronics and suitable for large-screen CRT TVs, flat-panel CRT monitors, HD CRT projection systems, and legacy broadcast equipment requiring stable component supply for repair, refurbishment, and niche production.

Supply support for HD1520FX 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, specializing in power discrete devices, automotive ICs, microcontrollers, and sensors.

HD1520FX belongs to ST's High-Voltage Power Transistor product line, developed specifically to address thermal, safety, and switching performance demands of analog CRT horizontal deflection circuits.

FAQ

Is HD1520FX still in active production?

No-HD1520FX is marked "Obsolete Product(s)" in its official STMicroelectronics datasheet (Rev. 1, May 2005). It is no longer manufactured, but Aetrix Electronics maintains limited legacy stock for repair and maintenance of installed CRT-based systems.

Can HD1520FX be mounted directly to a metal heatsink without insulation?

Yes-its ISOWATT218FX package provides full electrical isolation between all three terminals and the mounting flange, rated for 2500 V RMS. No mica washer or silicone pad is required, unlike non-insulated TO-3P devices.

What is the maximum safe operating frequency for HD1520FX in horizontal deflection?

The device is characterized for f_h = 31.25 kHz (100 Hz interlaced TV), with validated switching times (t_s = 3.2 µs, t_f = 220 ns) under inductive load conditions matching CRT yoke impedance and flyback voltage profiles.

Does HD1520FX require a base resistor for TTL-level drive?

Yes-a series base resistor is required to limit I_B to ≤8 A peak and ensure proper saturation. With I_C = 9 A and h_FE(min) = 5.5, minimum I_B ≈ 1.64 A; typical designs use 1–2 Ω, 5 W wirewound resistors for robust drive under temperature variation.

HD1520FX Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: ISOWATT218FX

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 15 A

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

Vce Saturation (Max) @ Ib, Ic:: 3V @ 1.8A, 9A

Current - Collector Cutoff (Max):: 200µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 5.5 @ 9A, 5V

Power - Max:: 64 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: ISOWATT-218FX

HD1520FX FAQ

1.How can I place an order for HD1520FX through Aetrix?

Please submit a Request for Quotation (RFQ) for HD1520FX 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 HD1520FX reliable?

The price and inventory of HD1520FX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for HD1520FX is usually 5 days.

3.What payment methods are accepted for HD1520FX?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for HD1520FX transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for HD1520FX?

HD1520FX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your HD1520FX 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 HD1520FX?

For technical support, including HD1520FX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your HD1520FX requirements.

6.How does Aetrix verify that HD1520FX is sourced from the original manufacturer or authorized distributors?

All HD1520FX 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 HD1520FX meets industry standards.

7.What is the process for return or replacement of HD1520FX?

All HD1520FX units undergo pre-shipment inspection (PSI). If there is an issue with HD1520FX, 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 HD1520FX part is unused and in its original packaging.

Return procedure for HD1520FX:

1.Submit a request within 90 days.

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

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