Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

onsemi 2SA2125-TD-H

Name: 2SA2125-TD-H
Brand: onsemi
SKU: 2SA2125-TD-H
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 2SA2125-TD-H

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-243AA

Datasheet:: 2SA2125-TD-H.pdf

Description:: TRANS PNP 50V 3A PCP

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,907

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

2SA2125-TD-H from onsemi is a PNP bipolar junction transistor designed for high-current switching in power control circuits, featuring −50 V V_CEO, −3 A I_C, low −125 mV V_CE(sat) at −1 A/−50 mA, SOT-89 package, and halogen-free construction. It is used in DC-DC converters, motor drivers, and lamp drivers where low saturation voltage and robust pulse current handling are required.

For engineers reviewing the 2SA2125-TD-H datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, confirmed SOT-89 terminal assignment (Base–Collector–Emitter), guaranteed −50 V breakdown rating, and documented 390 MHz f_T for high-speed switching performance.

Technical Context

This device employs onsemi's MBIT process to achieve low V_CE(sat) and high-speed switching with 30 ns t_on, 230 ns t_stg, and 18 ns t_f. Its PNP configuration supports high-side switching in industrial power stages, with validated operation up to T_j = 150°C and thermal dissipation of 3.5 W at T_C = 25°C on ceramic substrate.

The transistor delivers h_FE = 200–560 at V_CE = −2 V and I_C = −100 mA, and maintains stable gain across temperature (−25°C to +75°C). Cob = 24 pF at V_CB = −10 V enables predictable RF behavior in switching node applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−50 V - Ensures safe operation in 24–48 V DC bus switching applications without breakdown.
I_C	−3 A continuous - Supports motor and relay loads requiring sustained current drive.
V_CE(sat)	−125 mV @ −1 A/−50 mA - Minimizes conduction loss and heat generation in high-duty-cycle switches.
f_T	390 MHz - Enables clean edge transitions in PWM frequencies up to ~50 MHz with margin.
h_FE	200–560 - Provides stable current amplification for base-drive design across production lots.
Cob	24 pF @ V_CB = −10 V - Limits Miller effect during turn-off, improving switching consistency.
P_C (T_C = 25°C)	3.5 W - Allows direct mounting on ceramic substrates for thermally demanding industrial PCBs.

Pinout & Package

SOT-89 / PCP-1 package (4.50 × 2.50 × 1.50 mm, 1.50 mm pitch), surface-mount, three-terminal plastic case (Case 419AU), with exposed collector tab for thermal conduction.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control input requiring −50 mA typical drive for full saturation at −2 A load.
2	Collector	Main current sink terminal; electrically connected to exposed metal tab for heatsinking.
3	Emitter	Common reference node; tied to system ground or high-side rail return path in PNP topology.

Key Features

Feature	Design Value
Low V_CE(sat)	−125 mV at −1 A ensures <0.125 W conduction loss per device in 12 V systems.
High pulse current	−6 A I_CP supports short-duration inrush currents in solenoid and lamp startup.
Halogen-free construction	Meets IEC 61249-2-21 and JEDEC J-STD-020 for RoHS-compliant industrial assembly.
High-speed switching	30 ns t_on/18 ns t_f enables >10 MHz PWM operation with minimal dead-time overhead.
Thermal robustness	Rated for 150°C junction temperature and 3.5 W dissipation on ceramic substrate.

Applications

DC–DC Converter	Motor Driver
Use Scenario: Step-down (buck) converter output stage in 24 V industrial power supplies. IC Role / Device Role / Timing Role: PNP high-side switch controlling energy transfer to inductor and output capacitor. Use Value: Low −125 mV V_CE(sat) reduces conduction loss by >40% vs. standard PNP transistors at 1 A load.	Use Scenario: H-bridge upper-leg switch for brushed DC motors in factory automation actuators. IC Role / Device Role / Timing Role: High-side current sink enabling bidirectional control with complementary NPN/N-channel devices. Use Value: Verified −50 V V_CEO withstands back-EMF spikes up to 40 V during motor commutation.
Lamp Driver	Relay Driver
Use Scenario: Constant-current LED array driver in emergency lighting systems. IC Role / Device Role / Timing Role: Linear or PWM-controlled current regulator with emitter-follower configuration. Use Value: h_FE = 200–560 ensures stable current regulation across temperature without feedback loop redesign.	Use Scenario: Solid-state replacement for electromechanical relays in PLC output modules. IC Role / Device Role / Timing Role: High-current interface between microcontroller GPIO and relay coil (e.g., 24 V/100 mA). Use Value: −6 A I_CP accommodates relay coil inrush surges while maintaining <100 ns total switching delay.

DC–DC Converter

Motor Driver

Use Scenario: Step-down (buck) converter output stage in 24 V industrial power supplies.

IC Role / Device Role / Timing Role: PNP high-side switch controlling energy transfer to inductor and output capacitor.

Use Value: Low −125 mV V_CE(sat) reduces conduction loss by >40% vs. standard PNP transistors at 1 A load.

Use Scenario: H-bridge upper-leg switch for brushed DC motors in factory automation actuators.

IC Role / Device Role / Timing Role: High-side current sink enabling bidirectional control with complementary NPN/N-channel devices.

Use Value: Verified −50 V V_CEO withstands back-EMF spikes up to 40 V during motor commutation.

Lamp Driver

Relay Driver

Use Scenario: Constant-current LED array driver in emergency lighting systems.

IC Role / Device Role / Timing Role: Linear or PWM-controlled current regulator with emitter-follower configuration.

Use Value: h_FE = 200–560 ensures stable current regulation across temperature without feedback loop redesign.

Use Scenario: Solid-state replacement for electromechanical relays in PLC output modules.

IC Role / Device Role / Timing Role: High-current interface between microcontroller GPIO and relay coil (e.g., 24 V/100 mA).

Use Value: −6 A I_CP accommodates relay coil inrush surges while maintaining <100 ns total switching delay.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP high-current switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SA2125-TD-E	Pb-free but not halogen-free; identical electrical specs and SOT-89 mechanical form.	No difference in circuit function or layout; differs only in material compliance documentation.	Select when RoHS Pb-free compliance suffices and halogen-free certification is not mandated.
2SC5964-TD-H	NPN complement with matching V_CEO = 50 V, I_C = 3 A, f_T = 380 MHz, and same SOT-89 package.	Used in low-side switching or complementary pair configurations; not a drop-in replacement.	Choose for NPN-side matching in push-pull or totem-pole topologies requiring symmetrical performance.

Compared with 2SA2125-TD-E, the -TD-H variant adds halogen-free certification without electrical trade-offs; compared with 2SC5964-TD-H, it provides PNP polarity essential for high-side switching where NPN cannot be substituted without circuit rework.

Availability

2SA2125-TD-H is available at Aetrix Electronics and suitable for DC–DC converters, motor drivers, and relay drivers requiring stable component supply, long-term industrial lifecycle support, and halogen-free manufacturing compliance.

Supply support for 2SA2125-TD-H 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2SA2125-TD-H belongs to onsemi's general-purpose bipolar transistor product line, engineered for high-reliability discrete switching in industrial power conversion and motion control systems.

FAQ

What is the pin configuration of the 2SA2125-TD-H?

The 2SA2125-TD-H uses SOT-89 package with pin 1 = Base, pin 2 = Collector (connected to exposed tab), and pin 3 = Emitter. This layout is confirmed in the official onsemi datasheet (Order Number 2SA2125/D, page 2) and matches Case 419AU mechanical outline.

Is the 2SA2125-TD-H halogen-free and RoHS compliant?

Yes, the 2SA2125-TD-H is both halogen-free and RoHS compliant, as explicitly stated in the onsemi ordering information table (page 6): "Pb-Free & Halogen Free". This satisfies IEC 61249-2-21 and EU Directive 2011/65/EU requirements.

What is the maximum junction temperature rating for the 2SA2125-TD-H?

The 2SA2125-TD-H has a maximum junction temperature (T_j) rating of 150°C, as specified in the Absolute Maximum Ratings table (page 1) of the official datasheet. This allows reliable operation in enclosed industrial enclosures with ambient temperatures up to 85°C when properly heatsinked.

Can the 2SA2125-TD-H replace the 2SA2125-TD-E in existing designs?

Yes, the 2SA2125-TD-H is a direct replacement for the 2SA2125-TD-E in all electrical and mechanical respects; the only difference is halogen-free material content. No PCB or schematic changes are needed-both share identical SOT-89 footprint, pinout, and electrical specifications.

What is the typical gain-bandwidth product (f_T) of the 2SA2125-TD-H?

The typical f_T of the 2SA2125-TD-H is 390 MHz, measured at V_CE = −10 V and I_C = −500 mA (Electrical Characteristics table, page 2). This value is confirmed across production lots and supports high-frequency switching applications up to 50 MHz with adequate phase margin.

2SA2125-TD-H Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-243AA

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: PNP

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

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

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 100mA, 2A

Current - Collector Cutoff (Max):: 1µA (ICBO)

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

Power - Max:: 3.5 W

Frequency - Transition:: 390MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: PCP

2SA2125-TD-H FAQ

1.How can I place an order for 2SA2125-TD-H through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SA2125-TD-H 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 2SA2125-TD-H reliable?

The price and inventory of 2SA2125-TD-H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SA2125-TD-H is usually 5 days.

3.What payment methods are accepted for 2SA2125-TD-H?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SA2125-TD-H transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SA2125-TD-H?

2SA2125-TD-H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SA2125-TD-H 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 2SA2125-TD-H?

For technical support, including 2SA2125-TD-H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SA2125-TD-H requirements.

6.How does Aetrix verify that 2SA2125-TD-H is sourced from the original manufacturer or authorized distributors?

All 2SA2125-TD-H 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 2SA2125-TD-H meets industry standards.

7.What is the process for return or replacement of 2SA2125-TD-H?

All 2SA2125-TD-H units undergo pre-shipment inspection (PSI). If there is an issue with 2SA2125-TD-H, 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 2SA2125-TD-H part is unused and in its original packaging.

Return procedure for 2SA2125-TD-H:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…