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

STMicroelectronics STL72

Name: STL72
Brand: STMicroelectronics
SKU: STL72
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STL72

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: STL72.pdf

Description:: TRANS NPN 400V 1A TO-92

Quantity:: RFQ Add To RFQ list

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Inventory:6,634

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Product details

Overview

STL72 from STMicroelectronics is a high-voltage fast-switching NPN power transistor designed for CFL ballast circuits, featuring V_CEO = 400 V, I_C = 1 A, t_f = 0.3 µs, and R_thJC = 125 °C/W in TO-92 package. It employs cellular emitter structure with planar edge termination to sustain wide RBSOA while enabling rapid switching.

For engineers reviewing the STL72 datasheet, STL72 pinout, STL72 application, or STL72 equivalent, key selection criteria include high-voltage blocking (V_CEO = 400 V), low saturation voltage (V_CE(sat) = 0.25 V @ 0.4 A), group-specified h_FE (10–23), and thermal resistance suitability for compact fluorescent lamp driver designs.

Technical Context

The STL72 uses multi-epitaxial planar technology to achieve simultaneous high breakdown voltage and fast switching. Its cellular emitter layout and planar edge termination optimize trade-offs between ruggedness and dynamic performance, supporting reliable operation under inductive load switching with V_clamp = 300 V.

Designed specifically for CFL electronic ballasts, it operates with pulsed base drive (IB_M = 1 A peak) and sustains repetitive inductive turn-off stress without secondary breakdown, validated by RBSOA curves up to T_J = 150 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	400 V - Sustains full line-referenced switching in 230 VAC CFL ballasts without avalanche stress
I_C	1 A continuous - Supports typical CFL lamp currents up to 30 W output
t_f	0.3 µs - Enables >50 kHz switching frequency with minimal switching loss
V_CE(sat)	0.25 V @ 0.4 A/80 mA - Reduces conduction loss and self-heating in thermally constrained TO-92 housing
R_thJC	125 °C/W - Limits junction temperature rise to ≤125 °C at 1 W dissipation with minimal heatsinking
h_FE	10–23 (group-specified) - Ensures consistent base drive design across production lots for stable lamp ignition

Pinout & Package

STL72 is housed in TO-92 package (bulk) and TO-92AP (ammopack), with standardized lead configuration: Emitter (pin 1), Base (pin 2), Collector (pin 3), as confirmed by STMicroelectronics mechanical drawings and internal schematic (Figure 1).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Emitter	Reference node for base drive return and current sensing; directly connected to PCB ground plane in CFL half-bridge emitters
Pin 2	Base	Control input requiring 40–80 mA DC or pulsed drive; sensitive to ESD due to planar junction structure
Pin 3	Collector	High-voltage switching node tied to resonant tank; electrically isolated from case and requires creepage clearance ≥4 mm

Key Features

Feature	Design Value
High-voltage capability	V_CEO = 400 V enables direct interface with 230 VAC rectified bus without external snubbers
Low spread of dynamic parameters	Tight t_f distribution (±15%) ensures consistent timing across production batches in resonant lamp control
Very high switching speed	0.3 µs fall time supports zero-voltage switching (ZVS) in CFL half-bridge topologies
Wide RBSOA	Sustains 1 A at 400 V during turn-off transients, eliminating need for active clamping in cost-sensitive ballasts

Applications

Compact Fluorescent Lamp (CFL) Ballast

Electronic Starter Circuit

Use Scenario: High-frequency resonant inverter driving 11–30 W spiral CFL tubes.

IC Role / Device Role / Timing Role: Main switching transistor in half-bridge topology, handling 50–70 kHz square-wave switching with inductive load.

Use Value: Low V_CE(sat) and fast t_f reduce total power loss to <1.2 W, enabling thermally passive enclosure design.

Use Scenario: Preheat and ignition phase control in integrated CFL modules.

IC Role / Device Role / Timing Role: Fast-turn-on switch triggering series-resonant preheat current before main lamp strike.

Use Value: Group-specified h_FE ensures predictable base current demand, simplifying RC timing network design.

DC-AC Inverter for LED Drivers

Low-Power SMPS Auxiliary Switch

Use Scenario: Isolated flyback or forward converter auxiliary switch in hybrid LED+halogen retrofit lamps.

IC Role / Device Role / Timing Role: Secondary-side synchronous rectifier control switch operating at ≤100 kHz.

Use Value: V_CES = 700 V withstands reflected transients from transformer leakage inductance.

Use Scenario: Standby power supply switch in multi-rail consumer electronics.

IC Role / Device Role / Timing Role: High-voltage start-up switch replacing resistor-based bias networks.

Use Value: 1 A rating and 125 °C/W thermal resistance allow direct PCB mounting without heatsink in <5 W auxiliary rails.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BUL742	V_CEO = 1000 V, t_f = 0.5 µs, TO-126 package, higher R_thJC (83 °C/W)	Supports higher bus voltages but requires larger footprint and heatsinking	Select when >600 V blocking or >2 A peak current is required; not drop-in for TO-92 board layouts
BU2520A	V_CEO = 1500 V, I_C = 2 A, TO-220 package, slower t_f (0.8 µs)	Targeted at TV horizontal deflection; over-specified voltage, lower switching efficiency	Choose only if legacy board space allows TO-220 and system demands extreme voltage margin

Compared with BUL742 and BU2520A, STL72 offers optimal balance of voltage rating, switching speed, and TO-92 thermal-mechanical fit for CFL ballasts-enabling smaller size, lower BOM cost, and simpler thermal management than higher-voltage alternatives.

Availability

STL72 is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, electronic starter circuits, low-power SMPS auxiliary switches, and DC-AC inverters requiring stable component supply and long-lifecycle support.

Supply support for STL72 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 STL series targets cost-sensitive, high-volume lighting applications; STL72 was engineered specifically for robust, thermally efficient switching in compact fluorescent lamp electronic ballasts.

FAQ

What is the maximum safe operating voltage for STL72 in continuous DC mode?

The absolute maximum V_CES is 700 V with V_BE = 0, but continuous DC operation is limited to V_CEO = 400 V (I_B = 0). Exceeding 400 V risks secondary breakdown unless pulsed with strict duty cycle and thermal derating per Figure 3.

Does STL72 require a heatsink in typical CFL applications?

No heatsink is required in standard 230 VAC CFL ballasts dissipating ≤1 W. With R_thJC = 125 °C/W and T_J(max) = 150 °C, PCB copper area ≥2 cm² provides sufficient conduction cooling; thermal relief pads on pin 3 improve heat transfer.

How does group L vs. group H h_FE affect base drive design?

Group L guarantees h_FE ≥10 (I_C = 0.4 A), group H ≥15. Designers must size base resistors for worst-case h_FE = 10 to ensure saturation under all conditions; ST ships either group based on production availability.

Can STL72 replace BU2520A in existing TO-220 layouts?

No-STL72 uses TO-92/TO-92AP packages with different pinout, thermal path, and current rating. Direct replacement would require PCB redesign, new base drive sizing, and verification of RBSOA under identical inductive load conditions.

STL72 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 400 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 80mA, 400mA

Current - Collector Cutoff (Max):: 1mA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 10 @ 400mA, 5V

Power - Max:: 1 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92

STL72 FAQ

1.How can I place an order for STL72 through Aetrix?

Please submit a Request for Quotation (RFQ) for STL72 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 STL72 reliable?

The price and inventory of STL72 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STL72 is usually 5 days.

3.What payment methods are accepted for STL72?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STL72 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STL72?

STL72 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STL72 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 STL72?

For technical support, including STL72 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STL72 requirements.

6.How does Aetrix verify that STL72 is sourced from the original manufacturer or authorized distributors?

All STL72 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 STL72 meets industry standards.

7.What is the process for return or replacement of STL72?

All STL72 units undergo pre-shipment inspection (PSI). If there is an issue with STL72, 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 STL72 part is unused and in its original packaging.

Return procedure for STL72:

1.Submit a request within 90 days.

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

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