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

STMicroelectronics 2STN1550

Name: 2STN1550
Brand: STMicroelectronics
SKU: 2STN1550
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2STN1550

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-261-4, TO-261AA

Datasheet:: 2STN1550.pdf

Description:: TRANS NPN 50V 5A SOT-223

Quantity:: RFQ Add To RFQ list

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Inventory:50,275

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Product details

Overview

2STN1550 from STMicroelectronics is an NPN power transistor using PB-HCD (Power Bipolar High Current Density) technology, designed for medium-power switching and linear regulation. It delivers V_CE(sat) = 0.26 V at I_C = 3 A / I_B = 300 mA, h_FE ≥ 135 at I_C = 0.5 A, and operates up to T_J = 150 °C in SOT-223 package - used in LED drivers and battery chargers.

For engineers reviewing the 2STN1550 datasheet, 2STN1550 pinout, 2STN1550 application, or 2STN1550 equivalent, key selection criteria include saturation voltage under high-current switching, thermal resistance (R_thj-amb = 78 °C/W), DC current gain linearity across 0.5–5 A, and SOT-223 footprint compatibility with PCB thermal relief design.

Technical Context

The 2STN1550 is a silicon bipolar junction transistor optimized for low-V_CE(sat) and high h_FE in continuous and pulsed medium-power operation. Its PB-HCD process enables 5 A continuous collector current and 10 A peak (t_P < 5 ms) while maintaining tight V_BE(sat) = 1.0–1.2 V range.

It functions as a single-polarity current-controlled switch or linear amplifier with fixed-emitter configuration. The device requires external base drive limiting and relies on PCB copper area (1 cm²) for thermal management per its R_thj-amb = 78 °C/W rating.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CE(sat)	0.26 V @ I_C = 3 A, I_B = 300 mA - enables <1 W conduction loss in 5 A switching paths
h_FE	135 min @ I_C = 0.5 A, V_CE = 2 V - reduces required base drive current in driver stages
P_TOT	1.6 W @ T_amb = 25 °C - sets maximum steady-state power dissipation with standard SOT-223 PCB layout
R_thj-amb	78 °C/W - defines junction-to-ambient temperature rise per watt with 1 cm² copper pad
V_CEO	50 V - supports 24 V system rails with 100 % margin against transients
t_off	700 ns @ resistive load - limits switching losses in PWM frequencies up to ~500 kHz

Pinout & Package

SOT-223 package: 4-pin surface-mount outline with exposed emitter tab (pin 2) for thermal and electrical connection; pin 1 = base, pin 2 = emitter, pin 3 = collector, pin 4 = emitter (tab).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Base	Current-controlled input node requiring 300 mA drive for full saturation at 3 A output
Pin 2 & Pin 4	Emitter	Common emitter node tied to PCB ground plane via thermal pad - primary heat path and return path
Pin 3	Collector	Main high-current output terminal - connected to load or supply rail in low-side switch configuration

Key Features

Feature	Design Value
Low V_CE(sat)	0.26 V enables <0.8 W conduction loss at 3 A - critical for thermally constrained LED and charger designs
High h_FE	Min 135 at 0.5 A ensures stable gain across operating range - simplifies base resistor selection
Fast switching	90 ns t_on/700 ns t_off supports efficient PWM control up to 500 kHz without excessive gate drive complexity
SOT-223 thermal performance	R_thj-amb = 78 °C/W with 1 cm² PCB copper - exceeds SOT-89 by 12.4 % for same ambient conditions

Applications

LED Driver

Battery Charger

Use Scenario: Constant-current switching stage in portable LED flash circuits with 3–5 V input and 1–3 A output.

IC Role / Device Role / Timing Role: Low-side NPN switch controlling LED string current via PWM duty cycle.

Use Value: 0.26 V V_CE(sat) minimizes dropout and extends battery runtime vs. higher-saturation alternatives.

Use Scenario: Linear or switching pass element in 5–12 V wall-adaptor-based NiMH/Li-ion chargers.

IC Role / Device Role / Timing Role: Series pass transistor regulating charging current with feedback from sense resistor.

Use Value: 1.6 W P_TOT and 78 °C/W thermal resistance allow stable 1.5 A continuous operation on standard FR4.

Mobile Equipment Power Control

Voltage Regulation

Use Scenario: Load switching for auxiliary rails (e.g., camera module, SIM card, backlight) in smartphones and tablets.

IC Role / Device Role / Timing Role: High-gain NPN switch enabling microcontroller GPIO direct drive without buffer stage.

Use Value: h_FE ≥ 135 at 0.5 A allows 3.3 V MCU pins to fully saturate the transistor with ≤10 kΩ base resistor.

Use Scenario: Medium-current series regulator in industrial sensor nodes or embedded controllers requiring clean 5 V or 3.3 V.

IC Role / Device Role / Timing Role: Discrete pass element in adjustable LDO topology with external error amplifier.

Use Value: 50 V V_CEO headroom supports input up to 36 V while maintaining safe SOA during line transients.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD127	V_CE(sat) = 0.5 V @ I_C = 3 A - 92 % higher than 2STN1550; h_FE = 25–250 (wider spread)	Higher conduction loss limits use in >1 A continuous LED drivers	Prefer where cost sensitivity outweighs thermal efficiency in low-duty-cycle loads
ZTX653	P_TOT = 1.0 W; R_thj-amb = 125 °C/W - 60 % worse thermal performance; V_CE(sat) = 0.35 V	Not suitable for sustained 2 A+ operation without forced cooling	Select only for space-constrained SOT-23 designs where 500 mA max current suffices

Compared with MJD127 and ZTX653, the 2STN1550 offers superior thermal capability (78 °C/W), lowest V_CE(sat), and tighter h_FE distribution - making it optimal for compact, high-efficiency 1–5 A switching regulators and LED drivers where board-level thermal management is limited.

Availability

2STN1550 is available at Aetrix Electronics and suitable for LED drivers, battery chargers, and mobile equipment power control requiring stable component supply and consistent SOT-223 thermal performance.

Supply support for 2STN1550 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, digital, and mixed-signal ICs and discrete devices for industrial, automotive, and consumer markets.

The 2STN1550 belongs to ST's "Power Bipolar" product line, engineered specifically for high-current, low-saturation-voltage switching in space-constrained medium-power applications - emphasizing thermal efficiency and gain stability over wide current ranges.

FAQ

What is the maximum continuous collector current for the 2STN1550?

The 2STN1550 is rated for 5 A continuous collector current (I_C) at T_amb = 25 °C with adequate PCB copper area. Derating is required above 25 °C ambient per its R_thj-amb = 78 °C/W specification - e.g., ~3.2 A at 60 °C ambient with 1 cm² copper.

Can the 2STN1550 be used in linear regulator configurations?

Yes - its 50 V V_CEO, 1.6 W P_TOT, and stable h_FE make it suitable for medium-current series pass regulation. Designers must ensure SOA compliance under worst-case dropout and load conditions, and verify thermal margin using measured R_thj-amb with actual PCB layout.

Is the SOT-223 pinout compatible with standard footprint libraries?

Yes - the 2STN1550 uses JEDEC-standard SOT-223 mechanical dimensions: pin 1 (base), pin 2 (emitter), pin 3 (collector), pin 4 (emitter tab). Footprint libraries compliant with MO-178AA (SOT-223) will match its 6.5 mm × 3.5 mm body and 2.3 mm lead pitch.

Does the 2STN1550 meet RoHS and lead-free requirements?

Yes - the device is supplied in ECOPACK® packaging with lead-free second-level interconnect, compliant with JEDEC Standard JESD97 and EU RoHS Directive 2011/65/EU. The inner box label indicates the lead-free category and maximum soldering temperature ratings.

2STN1550 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-261-4, TO-261AA

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 5 A

Voltage - Collector Emitter Breakdown (Max):: 50 V

Vce Saturation (Max) @ Ib, Ic:: 450mV @ 300mA, 3A

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 135 @ 2A, 2V

Power - Max:: 1.6 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-223

2STN1550 FAQ

1.How can I place an order for 2STN1550 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2STN1550 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 2STN1550 reliable?

The price and inventory of 2STN1550 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2STN1550 is usually 5 days.

3.What payment methods are accepted for 2STN1550?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2STN1550 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2STN1550?

2STN1550 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2STN1550 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 2STN1550?

For technical support, including 2STN1550 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2STN1550 requirements.

6.How does Aetrix verify that 2STN1550 is sourced from the original manufacturer or authorized distributors?

All 2STN1550 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 2STN1550 meets industry standards.

7.What is the process for return or replacement of 2STN1550?

All 2STN1550 units undergo pre-shipment inspection (PSI). If there is an issue with 2STN1550, 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 2STN1550 part is unused and in its original packaging.

Return procedure for 2STN1550:

1.Submit a request within 90 days.

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

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