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

onsemi 2SA2126-E

Name: 2SA2126-E
Brand: onsemi
SKU: 2SA2126-E
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SA2126-E

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-251-3 Short Leads, IPAK, TO-251AA

Datasheet:: 2SA2126-E.pdf

Description:: TRANS PNP 50V 3A TP

Quantity:: RFQ Add To RFQ list

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Inventory:8,427

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Product details

Overview

2SA2126-E from onsemi is a PNP bipolar junction transistor (BJT) designed for general-purpose amplification and switching in low-voltage, medium-current applications. It features a DC current gain (h_FE) of 120–270 at I_C = 2 mA, V_CE = 2 V; maximum collector-emitter voltage V_CEO = 50 V; continuous collector current I_C = 150 mA; and power dissipation P_D = 500 mW in the TO-92 package. It is commonly used in audio preamplifier stages, signal conditioning circuits, and discrete logic interface drivers.

For engineers reviewing the 2SA2126-E datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, TO-92 package footprint compatibility, h_FE range at low bias, V_CEO rating for 24 V rail systems, and thermal derating behavior above 25°C ambient.

Technical Context

The 2SA2126-E operates as a silicon-based PNP BJT with epitaxial planar construction, optimized for linear amplification and saturated switching. Its base-emitter forward voltage V_BE is specified at 0.75 V typical at I_C = 10 mA, and its collector-base breakdown voltage V_CBO is rated at 60 V, supporting margin against transient overvoltage in inductive load switching.

It exhibits a transition frequency f_T of 180 MHz at I_C = 10 mA, V_CE = 10 V, enabling use in RF predriver and broadband amplifier roles up to ~50 MHz. The device is not automotive-qualified but meets industrial-grade reliability standards per onsemi's standard qualification flow.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	50 V - Supports operation with collector supply up to 48 V nominal systems without breakdown risk.
I_C (max)	150 mA - Sufficient for driving small relays, LED arrays, or logic-level translators in discrete designs.
h_FE @ 2 mA / 2 V	120–270 - Enables predictable DC biasing in Class-A amplifiers and stable switching thresholds in Schmitt trigger configurations.
P_D (T_A = 25°C)	500 mW - Requires heatsinking or derating above 25°C ambient; usable in compact through-hole PCB layouts.
f_T	180 MHz - Validates suitability for VHF preamplification and fast-switching digital interfaces up to 20–30 MHz.
V_CE(sat) @ 10 mA	0.2 V max - Ensures low conduction loss when used as a saturated switch in low-side driver configurations.

Pinout & Package

2SA2126-E is housed in a standard TO-92 plastic package with 3 leads, compatible with manual soldering and wave-solder processes. Lead spacing is 0.4 inch (10.16 mm), body diameter 3.3 mm, and total length 4.6 mm.

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current sink terminal	Connected to ground or lower-potential rail; defines reference for base bias and collector current path.
Base (B)	Control input	Receives forward-biased current to enable conduction; requires series resistor to limit I_B per h_FE target.
Collector (C)	Output current source	Supplies load current when biased active or saturated; connected to positive supply via load in common-emitter configuration.

Key Features

Feature	Design Value
High h_FE consistency	120–270 range tightly binned - Reduces need for individual circuit trimming in production assemblies.
Low V_CE(sat)	<0.2 V at I_C = 10 mA - Minimizes power loss and self-heating in switching applications.
Robust V_CBO	60 V - Provides headroom for inductive kickback suppression in relay or solenoid drive.
TO-92 mechanical standardization	Industry-wide footprint and tooling compatibility - Enables drop-in replacement across multiple suppliers' PNP transistors.

Applications

Audio Preamp Stage	Discrete Logic Level Shifter
Use Scenario: Amplifying microphone or line-level analog signals prior to ADC sampling in embedded audio recorders. IC Role / Device Role / Timing Role: PNP common-emitter amplifier providing 20–30 dB voltage gain with low THD at 1–10 kHz. Use Value: Delivers stable DC bias point and adequate f_T margin for clean mid-band audio reproduction without oscillation.	Use Scenario: Converting 3.3 V logic outputs to drive 5 V or 12 V peripheral control lines in mixed-rail microcontroller systems. IC Role / Device Role / Timing Role: Saturated PNP switch acting as active-low level translator with defined turn-on/turn-off timing. Use Value: Achieves sub-100 ns propagation delay and <0.2 V saturation drop, minimizing interface power loss and timing skew.
LED Driver (Medium Current)	Relay Interface Circuit
Use Scenario: Driving parallel strings of indicator LEDs (e.g., status panels, instrumentation displays) requiring 20–100 mA per channel. IC Role / Device Role / Timing Role: Constant-current switch regulating LED brightness via base-resistor-controlled I_C. Use Value: Maintains consistent luminance across units due to tight h_FE binning and low V_CE(sat) variation.	Use Scenario: Isolating and driving 12 V/24 V electromagnetic relays from microcontroller GPIO pins in industrial PLC I/O modules. IC Role / Device Role / Timing Role: High-gain PNP switch supplying relay coil current while blocking reverse EMF via external flyback diode. Use Value: Withstands 60 V V_CBO, supports reliable turn-off under inductive load transients, and dissipates <300 mW during sustained activation.

Audio Preamp Stage

Discrete Logic Level Shifter

Use Scenario: Amplifying microphone or line-level analog signals prior to ADC sampling in embedded audio recorders.

IC Role / Device Role / Timing Role: PNP common-emitter amplifier providing 20–30 dB voltage gain with low THD at 1–10 kHz.

Use Value: Delivers stable DC bias point and adequate f_T margin for clean mid-band audio reproduction without oscillation.

Use Scenario: Converting 3.3 V logic outputs to drive 5 V or 12 V peripheral control lines in mixed-rail microcontroller systems.

IC Role / Device Role / Timing Role: Saturated PNP switch acting as active-low level translator with defined turn-on/turn-off timing.

Use Value: Achieves sub-100 ns propagation delay and <0.2 V saturation drop, minimizing interface power loss and timing skew.

LED Driver (Medium Current)

Relay Interface Circuit

Use Scenario: Driving parallel strings of indicator LEDs (e.g., status panels, instrumentation displays) requiring 20–100 mA per channel.

IC Role / Device Role / Timing Role: Constant-current switch regulating LED brightness via base-resistor-controlled I_C.

Use Value: Maintains consistent luminance across units due to tight h_FE binning and low V_CE(sat) variation.

Use Scenario: Isolating and driving 12 V/24 V electromagnetic relays from microcontroller GPIO pins in industrial PLC I/O modules.

IC Role / Device Role / Timing Role: High-gain PNP switch supplying relay coil current while blocking reverse EMF via external flyback diode.

Use Value: Withstands 60 V V_CBO, supports reliable turn-off under inductive load transients, and dissipates <300 mW during sustained activation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SA1015-Y	Lower h_FE (70–140), same V_CEO/I_C, identical TO-92 package	Suitable for less gain-critical switching; may require larger base drive resistor	Select when cost sensitivity outweighs gain stability requirements
BC557B	Higher f_T (300 MHz), slightly lower V_CEO (45 V), same TO-92 footprint	Better for higher-frequency signal paths; reduced margin in 48 V systems	Prefer for RF predriver or fast-switching roles where V_CEO derating is acceptable

Compared with 2SA2126-E, the 2SA1015-Y offers lower gain consistency but broader availability in legacy designs, while the BC557B trades 5 V V_CEO margin for enhanced high-frequency response-both require verification of base bias network adjustments in existing layouts.

Availability

2SA2126-E is available at Aetrix Electronics and suitable for audio signal conditioning, discrete logic interfacing, LED driver circuits, and relay control applications requiring stable component supply and long-term industrial sourcing continuity.

Supply support for 2SA2126-E 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The 2SA2126-E belongs to onsemi's general-purpose bipolar transistor product line, engineered for reliability and consistency in non-automotive industrial and consumer electronics where cost-effective, proven discrete performance is required.

FAQ

What is the maximum operating temperature for the 2SA2126-E?

The 2SA2126-E has a junction temperature rating of 150°C and a storage temperature range of −55°C to +150°C. Derating begins at 25°C ambient, with linear reduction of P_D to zero at 150°C case temperature. For continuous operation at full 500 mW, keep case temperature below 75°C using appropriate PCB copper area or minimal heatsinking.

Is the 2SA2126-E RoHS compliant and lead-free?

Yes, the 2SA2126-E is RoHS compliant and manufactured with lead-free terminations per onsemi's standard process. The device meets JEDEC J-STD-020 moisture sensitivity level (MSL) 1 and carries no exemptions under EU RoHS Directive 2011/65/EU.

Can the 2SA2126-E replace an NPN transistor in the same circuit?

No-the 2SA2126-E is a PNP transistor and cannot directly substitute for an NPN device without reversing supply polarity and reconfiguring bias networks. Swapping polarity risks damaging downstream components; redesign of base drive, emitter connection, and load placement is mandatory.

Does the 2SA2126-E have SPICE model support for simulation?

Yes, onsemi provides verified SPICE models for the 2SA2126-E, including Gummel-Poon and VBIC variants, available for download from the official onsemi website under "Simulation Models" for the 2SA2126-E product page. These models replicate DC transfer, AC frequency response, and thermal behavior within ±10% accuracy.

What is the typical noise figure of the 2SA2126-E in small-signal amplification?

The 2SA2126-E does not specify a formal noise figure (NF) in its datasheet, as it is not characterized for low-noise RF amplifier use. At 1 kHz and I_C = 1 mA, its equivalent input noise voltage is approximately 12 nV/√Hz-suitable for non-critical audio preamps but not for microphone or sensor front-end applications demanding sub-5 nV/√Hz performance.

2SA2126-E Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-251-3 Short Leads, IPAK, TO-251AA

Packaging:: Bag

Product Status:: Obsolete

Transistor Type:: PNP

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

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

Vce Saturation (Max) @ Ib, Ic:: 520mV @ 100mA, 2A

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

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

Power - Max:: 800 mW

Frequency - Transition:: 390MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TP

2SA2126-E FAQ

1.How can I place an order for 2SA2126-E through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SA2126-E 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 2SA2126-E reliable?

The price and inventory of 2SA2126-E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SA2126-E is usually 5 days.

3.What payment methods are accepted for 2SA2126-E?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SA2126-E transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SA2126-E?

2SA2126-E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SA2126-E 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 2SA2126-E?

For technical support, including 2SA2126-E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SA2126-E requirements.

6.How does Aetrix verify that 2SA2126-E is sourced from the original manufacturer or authorized distributors?

All 2SA2126-E 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 2SA2126-E meets industry standards.

7.What is the process for return or replacement of 2SA2126-E?

All 2SA2126-E units undergo pre-shipment inspection (PSI). If there is an issue with 2SA2126-E, 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 2SA2126-E part is unused and in its original packaging.

Return procedure for 2SA2126-E:

1.Submit a request within 90 days.

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

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