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

STMicroelectronics STN1802

Name: STN1802
Brand: STMicroelectronics
SKU: STN1802
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STN1802

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

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

Datasheet:: STN1802.pdf

Description:: TRANS NPN 60V 3A SOT-223

Quantity:: RFQ Add To RFQ list

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Inventory:6,012

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Product details

Overview

STN1802 from STMicroelectronics is a low-voltage, fast-switching NPN power transistor in SOT-223 package, rated for 60 V V_CEO, 3 A I_C, and 1.6 W P_tot, with V_CE(sat) as low as 150 mV at I_C = 2 A / I_B = 100 mA, optimized for CCFL drivers and low-voltage switching regulators.

For engineers reviewing the STN1802 datasheet, STN1802 pinout, STN1802 application, or STN1802 equivalent, key selection criteria include saturation voltage under high-current drive, h_FE stability at I_C = 3 A, thermal resistance (R_thj-amb = 78 °C/W on 1 cm² PCB), and switching timing (t_ON = 50 ns, t_f = 120 ns) in medium-power surface-mount designs.

Technical Context

This NPN planar transistor uses a "Base Island" layout to achieve high DC current gain (h_FE = 200–400 at I_C = 100 mA) while maintaining very low V_CE(sat) (≤300 mV at I_C = 3 A / I_B = 150 mA) and fast switching performance (f_T = 150 MHz, t_ON = 50 ns).

Designed for operation up to T_j = 150 °C with R_thj-amb = 78 °C/W on standard 1 cm² copper area, it supports pulsed peak currents up to 6 A (t_p < 5 ms) and withstands V_CB = 80 V and V_EB = 6 V without breakdown.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 V - maximum safe collector-emitter voltage with base open, enabling use in 48 V and lower DC supply rails
I_C	3 A continuous - supports medium-power switching loads such as relay coils and CCFL inverters
V_CE(sat)	150 mV @ I_C=2 A/I_B=100 mA - minimizes conduction loss and self-heating in high-duty-cycle applications
h_FE	200–400 @ I_C=100 mA - ensures reliable base drive margin and stable gain across production lots
f_T	150 MHz - enables clean square-wave switching up to ~10–20 MHz fundamental frequencies
t_ON/t_f	50 ns / 120 ns - reduces switching transition losses in PWM-controlled regulators and lamp drivers
R_thj-amb	78 °C/W on 1 cm² PCB - defines thermal derating curve for ambient temperatures up to 75 °C at full I_C

Pinout & Package

SOT-223 surface-mount package with 4-terminal configuration (3 active pins + tab); thermally enhanced plastic case with exposed collector tab for direct PCB heat sinking.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Low-impedance path for emitter return; electrically isolated from tab; connects to ground or low-side reference
2 (Base)	Control input	Receives forward bias current to saturate transistor; requires series resistor to limit I_B ≤ 1 A peak
3 (Collector)	High-current output	Connected internally to exposed metal tab; must be soldered to large copper pour for thermal management
Tab (Collector)	Thermal & electrical node	Primary heat dissipation path and functional collector connection; not insulated - requires clearance from other nets

Key Features

Feature	Design Value
Very low V_CE(sat)	150 mV at I_C = 2 A - reduces power loss by >40% vs. standard NPN transistors with 300+ mV saturation
High h_FE at high current	100 min @ I_C = 3 A - maintains strong drive efficiency even under full-load conditions
Fast switching speed	t_ON = 50 ns, t_f = 120 ns - enables high-frequency PWM control without excessive switching loss
Robust thermal design	R_thj-amb = 78 °C/W on 1 cm² PCB - allows 1.6 W dissipation with ΔT ≈ 125 °C above ambient

Applications

CCFL Backlight Driver

Voltage Regulator Switch

Use Scenario: Driving resonant inverter stage for cold cathode fluorescent lamps in LCD monitors.

IC Role / Device Role / Timing Role: Main high-current switching element in Royer or push-pull topology, operating at 50–100 kHz.

Use Value: Low V_CE(sat) minimizes conduction loss during 50% duty cycle, improving inverter efficiency by ≥3% over comparable transistors.

Use Scenario: Pass transistor in linear or quasi-resonant low-dropout regulator for 3.3 V/5 V systems.

IC Role / Device Role / Timing Role: Series pass element controlled by error amplifier feedback loop.

Use Value: High h_FE reduces base drive current requirement, lowering quiescent power and simplifying bias network design.

Electromechanical Relay Driver

Low-Voltage DC-DC Switch

Use Scenario: Direct coil driver for 12 V/24 V industrial relays with 100–500 Ω coil impedance.

IC Role / Device Role / Timing Role: Single-stage saturated switch replacing Darlington pairs in compact PCB layouts.

Use Value: Fast turn-off (t_f = 120 ns) eliminates relay contact bounce delay, enabling precise timing-critical sequencing.

Use Scenario: Primary switch in non-isolated buck converter for battery-powered instrumentation.

IC Role / Device Role / Timing Role: High-efficiency synchronous or diode-assisted switching node handling 2–3 A load current.

Use Value: f_T = 150 MHz supports clean gate drive edge integrity, reducing EMI in sensitive analog subsystems.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD122	V_CEO = 100 V, V_CE(sat) = 1.2 V @ I_C = 3 A - higher saturation loss, lower gain uniformity	Better suited for higher-voltage, lower-speed industrial controls where thermal margin is less constrained	Select when absolute V_CEO > 70 V is required and efficiency is secondary to ruggedness
ZTX851	h_FE = 100–300 @ I_C = 1 A, R_thj-amb = 120 °C/W - lower gain consistency and poorer thermal performance	Used in legacy audio amplifiers and low-cost consumer power stages with relaxed thermal budgets	Choose only if footprint compatibility with TO-92 is mandatory and power density is not critical

Compared with MJD122 and ZTX851, STN1802 delivers superior efficiency per unit area due to its 150 mV V_CE(sat), 78 °C/W thermal resistance, and 150 MHz f_T, making it optimal for space-constrained, thermally demanding medium-power switching where both speed and conduction loss matter.

Availability

STN1802 is available at Aetrix Electronics and suitable for CCFL drivers, voltage regulators, and relay drivers requiring stable component supply in industrial, medical display, and embedded power management systems.

Supply support for STN1802 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, power, MCU, and sensor solutions for automotive, industrial, and consumer markets.

The STN1802 belongs to ST's medium-power bipolar transistor product line, engineered specifically for high-efficiency, surface-mount switching in space- and thermal-constrained applications below 60 V.

FAQ

What is the maximum allowable base current for continuous operation?

The absolute maximum base current (I_B) is 1 A, but for reliable long-term operation at I_C = 3 A, ST recommends limiting I_B to 150 mA per the datasheet test condition for V_CE(sat). Exceeding this risks localized heating and gain degradation, especially without forced airflow or enhanced copper area.

Can STN1802 replace a Darlington pair in relay driving applications?

Yes - its h_FE ≥ 100 at I_C = 3 A and V_CE(sat) ≤ 300 mV allow single-transistor replacement of many Darlington configurations. Unlike Darlingtons, it avoids V_BE × 2 drop and storage time penalties, enabling faster turn-off and reduced base drive complexity.

Is the exposed collector tab electrically isolated?

No - the metal tab is internally connected to the collector terminal (Pin 3). It must be mounted on a non-isolated copper pour or insulated via thermal pad with dielectric layer if isolation from PCB ground is required. Electrical shorts will occur if tab contacts adjacent signal traces or planes.

What PCB layout practices optimize thermal performance?

Use ≥1 cm² of 2-oz copper connected directly to the collector tab, with ≥4 thermal vias (0.3 mm diameter) beneath the tab to inner ground/power planes. Keep base/emitter traces short and wide to minimize inductance, and avoid routing sensitive analog traces near the collector node to prevent coupling from fast switching edges.

STN1802 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 400mV @ 150mA, 3A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 100mA, 2V

Power - Max:: 1.6 W

Frequency - Transition:: 150MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-223

STN1802 FAQ

1.How can I place an order for STN1802 through Aetrix?

Please submit a Request for Quotation (RFQ) for STN1802 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 STN1802 reliable?

The price and inventory of STN1802 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STN1802 is usually 5 days.

3.What payment methods are accepted for STN1802?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STN1802 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STN1802?

STN1802 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STN1802 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 STN1802?

For technical support, including STN1802 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STN1802 requirements.

6.How does Aetrix verify that STN1802 is sourced from the original manufacturer or authorized distributors?

All STN1802 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 STN1802 meets industry standards.

7.What is the process for return or replacement of STN1802?

All STN1802 units undergo pre-shipment inspection (PSI). If there is an issue with STN1802, 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 STN1802 part is unused and in its original packaging.

Return procedure for STN1802:

1.Submit a request within 90 days.

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

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