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

STMicroelectronics 2STN2540-A

Name: 2STN2540-A
Brand: STMicroelectronics
SKU: 2STN2540-A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2STN2540-A

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

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

Datasheet:: 2STN2540-A.pdf

Description:: TRANS PNP 40V 5A SOT-223

Quantity:: RFQ Add To RFQ list

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Inventory:3,193

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Product details

Overview

2STN2540-A from STMicroelectronics is a PNP bipolar power transistor optimized for low-voltage, fast-switching applications in automotive and lighting systems. It features V_CEO = −40 V, I_C = −5 A, V_CE(sat) = −120 mV (at I_C = −1 A, I_B = −10 mA), h_FE = 200 (at I_C = −1 A), and SOT-223 surface-mount package - used in LED drivers and CCFL back-lighting circuits.

For engineers reviewing the 2STN2540-A datasheet, 2STN2540-A pinout, 2STN2540-A application, or 2STN2540-A equivalent, key selection criteria include saturation voltage under high-current switching, thermal resistance (R_thj-amb = 78 °C/W on 1 cm² PCB), automotive qualification status, and PNP drive compatibility with low-side control topologies.

Technical Context

This PNP transistor employs ST's PB-HCD (Power Bipolar High Current Density) process to achieve high DC current gain while maintaining ultra-low V_CE(sat). Its −40 V V_CEO rating and −5 A continuous collector current support robust operation in 12 V automotive supply rails and LED constant-current sink configurations.

Switching performance is characterized by t_on = 75 ns, t_s = 426 ns, and t_f = 62 ns into resistive loads at −10 V V_CC, enabling efficient PWM dimming in emergency lighting and backlight drivers where rapid turn-off minimizes cross-conduction loss.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−40 V: Maximum safe collector-emitter blocking voltage in open-base condition - enables use in 12–24 V automotive systems with margin.
I_C	−5 A: Continuous collector current rating - supports high-brightness LED strings or relay coils requiring >4 A load current.
V_CE(sat)	−120 mV @ I_C = −1 A, I_B = −10 mA: Low conduction loss reduces heat generation in linear-regulator or switch-mode driver stages.
h_FE	200 @ I_C = −1 A: High DC current gain allows low base drive current - simplifies microcontroller GPIO interfacing without external buffer stages.
R_thj-amb	78 °C/W on 1 cm² PCB: Thermal resistance defines junction-to-ambient rise per watt - requires ≥1 cm² copper pour for full 1.6 W dissipation at T_amb = 25 °C.
t_f	62 ns: Fast fall time ensures clean PWM edge transitions - critical for minimizing EMI and avoiding ghosting in CCFL backlights.

Pinout & Package

SOT-223 package: 4-pin surface-mount outline with exposed collector tab (pin 3) for thermal and electrical connection; standard pin assignment confirmed per Figure 1 and Table 1 of STMicroelectronics datasheet Rev 2 (Jan 2008).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitter terminal	Connected to positive rail in high-side switch configuration; provides return path for load current in PNP sink topology.
2 (Base)	Control input	Receives negative-going logic signal or active-low MCU output to enable conduction; requires current-limiting resistor for safe drive.
3 (Collector)	Main current path output	Exposed metal tab - electrically and thermally connected to collector; must be soldered to PCB copper pour for thermal management.
4 (Emitter)	Second emitter connection	Duplicate emitter pin for improved current sharing and lower bond-wire inductance - tied internally to pin 1.

Key Features

Feature	Design Value
Automotive qualification	Qualified per AEC-Q101 - validated for temperature cycling, humidity, and mechanical shock in vehicle cabin and under-hood environments.
Low V_CE(sat)	−120 mV at I_C = −1 A - reduces power loss by >40% vs. typical PNP transistors, extending thermal headroom in compact LED driver PCBs.
High h_FE	200 at I_C = −1 A - permits direct drive from 3.3 V/5 V microcontrollers with ≤10 mA base current, eliminating level-shifting circuitry.
Fast switching	t_f = 62 ns - enables PWM frequencies up to 2 MHz without significant duty-cycle distortion in backlight dimming applications.

Applications

LED Driver

CCFL Backlight

Use Scenario: Constant-current sinking for high-brightness white LED arrays in automotive interior lighting and emergency exit signs.

IC Role / Device Role / Timing Role: PNP power switch operating in linear or PWM mode to regulate LED current via emitter-follower or switched-sink topology.

Use Value: −120 mV V_CE(sat) limits conduction loss to <120 mW at 1 A, enabling compact thermal design without heatsinks on FR-4 PCBs.

Use Scenario: High-frequency AC drive for cold-cathode fluorescent lamps in LCD panel backlights.

IC Role / Device Role / Timing Role: Fast-switching PNP transistor in half-bridge or resonant inverter stage to generate 20–100 kHz lamp drive waveforms.

Use Value: 62 ns fall time ensures sharp voltage transitions, reducing lamp ignition delay and improving brightness uniformity across display zones.

Voltage Regulator

Relay Driver

Use Scenario: Pass element in low-dropout linear regulators supplying 5 V or 3.3 V to automotive infotainment subsystems.

IC Role / Device Role / Timing Role: PNP series pass transistor controlling output voltage via feedback-controlled base bias in adjustable LDO architecture.

Use Value: −40 V V_CEO withstands load-dump transients up to 35 V, meeting ISO 7637-2 Pulse 5a requirements without external clamping.

Use Scenario: Driving 12 V automotive relays (e.g., HVAC actuators, window lift modules) from microcontroller GPIO pins.

IC Role / Device Role / Timing Role: High-gain PNP switch providing >500 mA coil current with minimal base drive - configured as low-side grounded-load driver.

Use Value: h_FE = 200 at −1 A allows reliable relay pull-in using only 5 mA base current, compatible with standard 3.3 V MCU outputs.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD2955T4G	V_CEO = −60 V, I_C = −10 A, V_CE(sat) = −1.8 V @ I_C = −5 A - higher saturation voltage, larger die size	Higher power handling but slower switching (t_f ≈ 250 ns); suited for non-PWM linear regulation over wide temperature range	Select when higher voltage margin or ruggedness outweighs efficiency and speed requirements.
ZTX951	V_CEO = −60 V, I_C = −3 A, V_CE(sat) = −250 mV @ I_C = −1 A - lower current rating, higher V_CE(sat), TO-92 package	Through-hole mounting only; limited to <2 W dissipation; not automotive-qualified	Choose only for prototyping or low-volume non-automotive designs where SOT-223 footprint is unavailable.

Compared with MJD2955T4G and ZTX951, the 2STN2540-A delivers superior switching speed and lower conduction loss in SOT-223 form factor - making it optimal for space-constrained, high-efficiency automotive LED and backlight drivers where thermal management relies on PCB copper area rather than heatsinks.

Availability

2STN2540-A is available at Aetrix Electronics and suitable for LED drivers, CCFL backlights, and automotive relay control circuits requiring stable component supply and long-term production continuity.

Supply support for 2STN2540-A 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 automotive, industrial, and consumer markets.

The 2STN2540-A belongs to ST's automotive-qualified power bipolar transistor family, developed specifically for high-reliability, low-loss switching in 12 V vehicle electrical systems and energy-efficient lighting control.

FAQ

Is the 2STN2540-A still in active production?

No - STMicroelectronics has marked the 2STN2540-A as Obsolete Product(s) per its official datasheet revision history (Rev 2, Jan 2008). Aetrix Electronics maintains legacy inventory with full traceability and offers qualified drop-in alternatives upon request for ongoing production support.

What is the correct PCB pad layout for thermal reliability?

The SOT-223 package requires a minimum 1 cm² copper pour connected directly to pin 3 (collector tab) with ≥4 thermal vias (0.3 mm diameter, spaced ≤2 mm apart) to inner ground/power planes. This achieves the specified R_thj-amb = 78 °C/W and prevents junction overheating above 125 °C at 1.2 W dissipation.

Can the 2STN2540-A replace an NPN transistor in the same circuit?

No - it is a PNP device with inverted polarity: emitter connects to higher potential, collector to load/ground. Direct substitution would reverse bias conditions and cause immediate failure. Circuit redesign - including base drive polarity, feedback topology, and protection diodes - is required for PNP-to-NPN conversion.

Does the ECOPACK® marking indicate RoHS compliance?

Yes - ECOPACK® denotes ST's lead-free second-level interconnect and full compliance with RoHS Directive 2011/65/EU. The inner box label specifies JEDEC JESD97 category code, and maximum reflow profile (per J-STD-020) is documented in the package mechanical data section of the datasheet.

2STN2540-A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

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

Voltage - Collector Emitter Breakdown (Max):: 40 V

Vce Saturation (Max) @ Ib, Ic:: 450mV @ 500mA, 5A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 150 @ 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

2STN2540-A FAQ

1.How can I place an order for 2STN2540-A through Aetrix?

Please submit a Request for Quotation (RFQ) for 2STN2540-A 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 2STN2540-A reliable?

The price and inventory of 2STN2540-A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2STN2540-A is usually 5 days.

3.What payment methods are accepted for 2STN2540-A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2STN2540-A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2STN2540-A?

2STN2540-A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2STN2540-A 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 2STN2540-A?

For technical support, including 2STN2540-A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2STN2540-A requirements.

6.How does Aetrix verify that 2STN2540-A is sourced from the original manufacturer or authorized distributors?

All 2STN2540-A 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 2STN2540-A meets industry standards.

7.What is the process for return or replacement of 2STN2540-A?

All 2STN2540-A units undergo pre-shipment inspection (PSI). If there is an issue with 2STN2540-A, 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 2STN2540-A part is unused and in its original packaging.

Return procedure for 2STN2540-A:

1.Submit a request within 90 days.

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

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