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

STMicroelectronics ST26025A

Name: ST26025A
Brand: STMicroelectronics
SKU: ST26025A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ST26025A

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-204AA, TO-3

Datasheet:: ST26025A.pdf

Description:: TRANS PNP DARL 100V 20A TO-3

Quantity:: RFQ Add To RFQ list

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Inventory:5,956

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Product details

Overview

ST26025A from STMicroelectronics is a PNP power Darlington transistor in TO-3 metal package, designed for high-current linear and switching applications with V_CEO = −100 V, I_C = −20 A continuous, and P_TOT = 160 W at T_C = 25 °C. It integrates an antiparallel collector-emitter diode and is used in automotive fan control circuits.

For engineers reviewing the ST26025A datasheet, ST26025A pinout, ST26025A application, or ST26025A equivalent, key selection criteria include its monolithic Darlington gain (h_FE = 4500–18000), low V_CE(sat) (−2 V @ −10 A/−40 mA), thermal resistance (R_thJC = 1.1 °C/W), and TO-3 mechanical compatibility with heatsink mounting.

Technical Context

The ST26025A implements a monolithic PNP Darlington pair with integrated antiparallel diode across C–E, enabling bidirectional current handling in inductive load switching. Its epitaxial-base structure supports stable operation up to T_J = 200 °C and withstands V_CEO(sus) = −100 V under pulsed conditions.

Designed for low-frequency (<1 kHz) operation, it delivers high DC current gain (h_FE ≥ 750 @ −10 A) and low saturation voltage-critical for minimizing conduction loss in industrial motor drivers and automotive thermal management systems.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−100 V: Maximum safe collector-emitter blocking voltage with base open, suitable for 24 V/48 V automotive and industrial bus systems.
I_C	−20 A continuous: Sustained collector current rating at T_C = 25 °C, enabling direct drive of high-power fans or solenoids.
P_TOT	160 W: Total power dissipation capability at case temperature 25 °C, requiring robust heatsinking for full-load operation.
h_FE	4500 (min) @ −2 A: High DC current gain reduces required base drive current, easing interface with microcontrollers or logic-level drivers.
R_thJC	1.1 °C/W: Low junction-to-case thermal resistance enables efficient heat transfer to external heatsinks in TO-3 mounting.
V_CE(sat)	−2 V @ −10 A/−40 mA: Low saturation voltage minimizes conduction loss and self-heating during switching or linear regulation.

Pinout & Package

Package: TO-3 metal case with tab (collector-connected), standardized for bolt-down heatsink mounting and high-reliability thermal management.

Pin/Terminal	Circuit Role	Design Meaning
Collector (Tab)	Main current output terminal, electrically connected to metal case	Must be electrically isolated from heatsink unless circuit design requires common-collector configuration; primary thermal path.
Emitter	Current source terminal for PNP device	Connected to positive rail in high-side switch configurations; carries full load current.
Base	Control input for Darlington pair	Requires current-limited drive (max −0.5 A); internal R1 = 8 kΩ and R2 = 60 Ω bias network simplifies external component count.

Key Features

Feature	Design Value
Monolithic Darlington configuration	Single-die integration eliminates inter-device mismatch and improves thermal tracking vs. discrete pairs.
Integrated antiparallel C–E diode	Eliminates need for external flyback diode in inductive load switching, reducing BOM count and PCB area.
TO-3 metal package	Enables direct mechanical attachment to heatsinks with low thermal impedance and high mechanical ruggedness.
High h_FE with internal base resistors	R1 = 8 kΩ and R2 = 60 Ω provide built-in biasing, allowing TTL/CMOS-compatible base drive without external resistors.

Applications

Automotive Fan Control

Industrial DC Motor Driver

Use Scenario: PWM-controlled cooling fan in engine bay with 24 V supply and inductive back-EMF.

IC Role / Device Role / Timing Role: High-side PNP Darlington switch regulating fan speed via base-current modulation.

Use Value: Integrated antiparallel diode clamps inductive kickback; −100 V V_CEO ensures margin against load dump transients.

Use Scenario: Linear current regulator for small DC motors in packaging machinery.

IC Role / Device Role / Timing Role: Adjustable emitter-follower amplifier delivering precise load current with minimal external components.

Use Value: High h_FE (≥4500) enables microamp-level base control; TO-3 package sustains 160 W dissipation during stall conditions.

Linear Power Regulator

Switching Power Stage

Use Scenario: Pass element in adjustable 0–30 V, 15 A bench power supply.

IC Role / Device Role / Timing Role: Series pass transistor operating in active region with external op-amp feedback.

Use Value: Low R_thJC (1.1 °C/W) and high T_J(max) (200 °C) support stable thermal performance under sustained overload.

Use Scenario: Low-frequency (≤1 kHz) on/off switch for heating elements in industrial ovens.

IC Role / Device Role / Timing Role: Saturated-switch Darlington providing galvanic isolation between control logic and 48 V/20 A load.

Use Value: −2 V V_CE(sat) limits conduction loss to ≤40 W at full load, reducing heatsink requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD2955	TO-220 package, lower P_TOT (75 W), V_CEO = −70 V, no integrated diode	Suitable only for lower-power, non-inductive loads; requires external flyback diode	Select when space-constrained PCB layout prioritizes TO-220 over TO-3 and thermal budget allows ≤75 W.
BDX54C	TO-225AA package, V_CEO = −100 V, I_C = −12 A, no integrated diode, h_FE = 750–5000	Limited current capacity and missing antiparallel diode reduce suitability for automotive fan use	Consider only for cost-sensitive, lower-current linear amplifiers where diode omission is acceptable.

Compared with MJD2955 and BDX54C, the ST26025A uniquely combines TO-3 ruggedness, integrated flyback protection, and 20 A/160 W capability-making it irreplaceable in high-reliability automotive and industrial switching where thermal margin and BOM simplification are critical.

Availability

ST26025A is available at Aetrix Electronics and suitable for automotive thermal management, industrial motor control, linear power regulation, and switching power stages requiring stable component supply and long-term industrial availability.

Supply support for ST26025A 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 power devices.

The ST26025A belongs to ST's high-power bipolar transistor family, engineered specifically for robust, high-current switching and linear amplification in harsh-environment applications including automotive and industrial equipment.

FAQ

Is the ST26025A still in active production?

No-the ST26025A is marked "Obsolete Product(s)" in its official datasheet (Doc ID 18031 Rev 1, October 2010). However, Aetrix Electronics maintains legacy inventory with full traceability and offers extended lifecycle support including obsolescence mitigation planning and cross-reference guidance.

What is the function of the internal resistors R1 and R2 shown in Figure 1?

R1 (8 kΩ) and R2 (60 Ω) form an integrated base bias network that provides turn-on current limiting and turn-off discharge path. This eliminates external base resistors in many applications, simplifying drive circuitry while ensuring reliable Darlington saturation and cutoff behavior.

Can the ST26025A be used in avalanche mode?

No-the ST26025A is not rated or characterized for controlled avalanche operation. Its V_CEO(sus) rating applies only under specified pulse test conditions (≤300 µs, ≤2% duty cycle) and does not imply safe repetitive avalanche capability. Designers must implement external clamping or snubbing for inductive energy dissipation.

How is the collector terminal connected in the TO-3 package?

The collector is internally bonded to the metal tab of the TO-3 package, which serves as both the electrical collector terminal and primary thermal interface. When mounted, the tab must be electrically isolated from the heatsink unless the circuit explicitly requires collector-to-chassis connection.

ST26025A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-204AA, TO-3

Packaging:: Bag

Product Status:: Obsolete

Transistor Type:: PNP - Darlington

Current - Collector (Ic) (Max):: 20 A

Voltage - Collector Emitter Breakdown (Max):: 100 V

Vce Saturation (Max) @ Ib, Ic:: 3V @ 200mA, 20A

Current - Collector Cutoff (Max):: 1mA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 750 @ 10A, 3V

Power - Max:: 160 W

Frequency - Transition:: -

Operating Temperature:: 200°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Chassis Mount

Supplier Device Package:: TO-3

ST26025A FAQ

1.How can I place an order for ST26025A through Aetrix?

Please submit a Request for Quotation (RFQ) for ST26025A 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 ST26025A reliable?

The price and inventory of ST26025A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST26025A is usually 5 days.

3.What payment methods are accepted for ST26025A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST26025A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ST26025A?

ST26025A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ST26025A 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 ST26025A?

For technical support, including ST26025A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST26025A requirements.

6.How does Aetrix verify that ST26025A is sourced from the original manufacturer or authorized distributors?

All ST26025A 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 ST26025A meets industry standards.

7.What is the process for return or replacement of ST26025A?

All ST26025A units undergo pre-shipment inspection (PSI). If there is an issue with ST26025A, 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 ST26025A part is unused and in its original packaging.

Return procedure for ST26025A:

1.Submit a request within 90 days.

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

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