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

STMicroelectronics 2STA2121

Name: 2STA2121
Brand: STMicroelectronics
SKU: 2STA2121
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2STA2121

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-264-3, TO-264AA

Datasheet:: 2STA2121.pdf

Description:: TRANS PNP 250V 17A TO-264

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2STA2121 from STMicroelectronics is a high-power PNP epitaxial planar bipolar transistor designed for linear audio power amplification, featuring V_CEO = −250 V, I_C = −17 A, f_T = 25 MHz, and R_thj-case = 0.568 °C/W, deployed in TO-264 package for Class AB output stages.

For engineers reviewing the 2STA2121 datasheet, 2STA2121 pinout, 2STA2121 application, or 2STA2121 equivalent, key selection criteria include safe operating area at 125 °C, gain linearity under large-signal swing, complementary pairing with 2STC5949, and thermal derating above 25 °C case temperature.

Technical Context

This PNP transistor uses ST's BiT-LA (Bipolar transistor for linear amplifier) process to optimize h_FE linearity across I_C = −1 A to −7 A at V_CE = −5 V, with guaranteed V_(BR)CEO = −250 V under pulsed conditions (300 µs, ≤1.5% duty cycle).

It operates up to T_J = 150 °C, supports peak collector current of −34 A for <5 ms pulses, and delivers V_CE(sat) = −3 V at I_C = −8 A / I_B = −800 mA-enabling efficient Class AB push-pull output stage design with low conduction loss.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−250 V: Sustains full rail-to-rail voltage swing in high-voltage audio output stages without breakdown.
I_C	−17 A continuous: Supports ≥100 W RMS audio output into 4 Ω loads with proper heatsinking.
f_T	25 MHz: Enables stable wideband operation up to 20 kHz with margin for feedback loop stability.
R_thj-case	0.568 °C/W: Requires minimum 0.5 °C/W heatsink thermal resistance to maintain T_J ≤ 150 °C at 220 W dissipation.
h_FE	80–160 @ I_C = −1 A: Provides predictable base drive requirements and low distortion in linear biasing networks.
V_CE(sat)	−3 V @ I_C = −8 A: Limits conduction loss to ≤24 W per device in parallel-output configurations.

Pinout & Package

Delivered in TO-264 (ISOWATT218) package: isolated metal tab, vertical mounting, screw-hole compatible, lead-free second-level interconnect per ECOPACK® standard.

Pin/Terminal	Circuit Role	Design Meaning
Collector (Tab)	Main current sink terminal, electrically connected to metal case	Must be mounted to heatsink with electrically insulating but thermally conductive interface; defines reference for V_CE and V_CB.
Base	Current-controlled input node	Accepts negative base current to turn on; requires series resistor limiting I_B to ≤−800 mA for rated saturation.
Emitter	Current source terminal	Connected to positive rail in PNP common-emitter amplifier; carries full load current with minimal voltage drop.

Key Features

Feature	Design Value
BiT-LA process technology	Engineered for gain linearity over wide I_C range, reducing harmonic distortion in audio output stages.
Complementary pairing with 2STC5949	Enables matched push-pull output stage design with symmetrical V_CEO, I_C, and f_T specs.
Full characterization at 125 °C	Guarantees electrical parameters remain valid under sustained high-temperature operation in enclosed amplifiers.
ECOPACK® lead-free construction	Meets RoHS and JEDEC JESD97 marking requirements for environmentally compliant manufacturing and assembly.

Applications

High-Fidelity Audio Amplifier

Professional PA Output Stage

Use Scenario: Dual-rail ±100 V Class AB power amplifier delivering 150 W RMS into 8 Ω with THD <0.05%.

IC Role / Device Role / Timing Role: PNP output transistor in complementary pair with NPN 2STC5949, handling negative half-cycle current delivery.

Use Value: V_CEO = −250 V ensures 100 V rail margin; h_FE linearity minimizes crossover distortion at low output levels.

Use Scenario: 300 W continuous-duty stage in touring-grade loudspeaker management system.

IC Role / Device Role / Timing Role: Primary PNP switching element in quasi-complementary output topology with forced-air cooling.

Use Value: R_thj-case = 0.568 °C/W enables thermal stability at 125 °C case temperature during extended high-SPL operation.

Studio Monitor Power Module

Industrial Audio Signal Distribution

Use Scenario: Bi-amplified near-field monitor with discrete analog output stage per frequency band.

IC Role / Device Role / Timing Role: Final PNP gain stage driving low-impedance woofer section with DC-coupled feedback.

Use Value: V_CE(sat) = −3 V at −8 A reduces idle heating and improves efficiency in compact chassis designs.

Use Scenario: Centralized 70 V line amplifier feeding distributed ceiling speakers in commercial buildings.

IC Role / Device Role / Timing Role: High-voltage PNP output switch enabling transformerless 70 V line drive with fast transient response.

Use Value: f_T = 25 MHz supports clean reproduction of speech transients and background music harmonics up to 20 kHz.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage PNP audio amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJE15034	V_CEO = −250 V, I_C = −8 A, f_T = 4 MHz, R_thj-case = 1.25 °C/W	Lower current rating and bandwidth; suitable only for ≤50 W designs	Select when lower cost and reduced thermal budget justify trade-offs in output power and fidelity.
BDW93C	V_CEO = −100 V, I_C = −15 A, f_T = 3 MHz, R_thj-case = 0.83 °C/W	Half the breakdown voltage; requires dual-rail reduction or added protection circuitry	Choose only for legacy 50–70 V supply systems where board space limits heatsink size.

Compared with MJE15034 and BDW93C, the 2STA2121 uniquely balances high voltage (−250 V), high current (−17 A), and wide bandwidth (25 MHz) while maintaining low thermal resistance-making it the sole option for new high-fidelity, high-power linear amplifier designs requiring full rail utilization and low distortion.

Availability

2STA2121 is available at Aetrix Electronics and suitable for high-fidelity audio amplifiers, professional PA systems, and studio monitor power modules requiring stable component supply and long-term BOM continuity.

Supply support for 2STA2121 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 industrial, automotive, and consumer markets.

The 2STA2121 belongs to ST's high-power bipolar transistor family developed specifically for linear audio amplifier applications demanding high voltage, high current, and gain linearity-targeting professional and audiophile-grade equipment manufacturers.

FAQ

Is the 2STA2121 still in active production?

No-the official STMicroelectronics datasheet identifies 2STA2121 as "Obsolete Product(s)". However, Aetrix Electronics maintains legacy inventory with full traceability and offers lifecycle coordination support, including last-time buy planning and cross-reference guidance for redesign efforts.

Can the 2STA2121 be used in switching applications?

It is not recommended. The 2STA2121 is optimized for linear operation (BiT-LA process), with specified safe operating area curves and gain linearity-not switching speed or storage time. Its f_T = 25 MHz and lack of specified t_on/t_off make it unsuitable for PWM or SMPS use.

What is the correct mounting orientation for the TO-264 package?

The metal tab is the collector and must be electrically isolated from the heatsink using mica or ceramic washers unless the circuit design intentionally references the heatsink to collector potential. Mounting screws must apply uniform pressure across the full tab surface to ensure optimal thermal transfer per the 0.568 °C/W rating.

How does the 2STA2121 compare to its NPN complement 2STC5949?

Both share identical V_CEO (−250 V / +250 V), I_C (−17 A / +17 A), f_T (25 MHz), and R_thj-case (0.568 °C/W), with matched h_FE ranges and 125 °C characterization-enabling true complementary symmetry in push-pull output stages without gain or thermal mismatch.

2STA2121 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-264-3, TO-264AA

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 17 A

Voltage - Collector Emitter Breakdown (Max):: 250 V

Vce Saturation (Max) @ Ib, Ic:: 3V @ 800mA, 8A

Current - Collector Cutoff (Max):: 5µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 80 @ 1A, 5V

Power - Max:: 220 W

Frequency - Transition:: 25MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-264

2STA2121 FAQ

1.How can I place an order for 2STA2121 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2STA2121 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 2STA2121 reliable?

The price and inventory of 2STA2121 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2STA2121 is usually 5 days.

3.What payment methods are accepted for 2STA2121?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2STA2121 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2STA2121?

2STA2121 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2STA2121 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 2STA2121?

For technical support, including 2STA2121 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2STA2121 requirements.

6.How does Aetrix verify that 2STA2121 is sourced from the original manufacturer or authorized distributors?

All 2STA2121 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 2STA2121 meets industry standards.

7.What is the process for return or replacement of 2STA2121?

All 2STA2121 units undergo pre-shipment inspection (PSI). If there is an issue with 2STA2121, 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 2STA2121 part is unused and in its original packaging.

Return procedure for 2STA2121:

1.Submit a request within 90 days.

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

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