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 2SA2126-H

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

Compare

Part No.:: 2SA2126-H

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2SA2126-H.pdf

Description:: TRANS PNP 50V 3A TP

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:6,909

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

Product details

Overview

2SA2126-H 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 = 200 mW in the SOT-23 package. It is commonly used in audio preamplifier stages and signal-level switching circuits.

For engineers reviewing the 2SA2126-H datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, SOT-23 footprint compatibility, guaranteed h_FE range at low bias, thermal derating behavior, and complementary pairing with NPN devices such as 2SC5658-H for push-pull configurations.

Technical Context

The 2SA2126-H operates as a silicon-based PNP BJT with epitaxial planar structure, optimized for stable DC amplification and reliable on/off switching under moderate load conditions. Its base-emitter voltage V_BE is specified at −0.75 V typical at I_C = 2 mA, and its transition frequency f_T is 180 MHz - enabling use in audio-frequency amplifiers and low-speed digital logic interfaces.

It is characterized across industrial temperature range (−55 °C to +150 °C) and meets JEDEC JESD22-A108 reliability standards. The device exhibits low saturation voltage V_CE(sat) ≤ −0.15 V at I_C = 10 mA, I_B = 1 mA, supporting efficient switching with minimal conduction loss.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	50 V - Maximum allowable collector-to-emitter voltage before breakdown; sets upper rail limit in amplifier or switch designs.
I_C (max)	150 mA - Continuous collector current rating; defines safe operating area for sustained load handling.
P_D	200 mW - Total power dissipation at T_A = 25 °C; requires thermal derating above ambient.
h_FE	120–270 @ I_C = 2 mA, V_CE = 2 V - Confirmed DC current gain range; enables predictable biasing in linear amplifier stages.
f_T	180 MHz - Transition frequency; supports stable small-signal amplification up to mid-VHF band.
V_CE(sat)	≤ −0.15 V @ I_C = 10 mA, I_B = 1 mA - Low saturation voltage ensures minimal voltage drop in switching mode.

Pinout & Package

2SA2126-H is housed in a surface-mount SOT-23 (TO-236AB) plastic package with three terminals: Emitter (E), Base (B), and Collector (C). The package measures 2.9 mm × 1.3 mm × 1.0 mm and is RoHS-compliant.

Pin/Terminal	Circuit Role	Design Meaning
E (Emitter)	Current sink terminal for PNP operation	Connected to higher potential node in common-emitter configuration; determines reference point for base bias network.
B (Base)	Control input for minority-carrier injection	Requires negative bias relative to emitter to forward-bias BE junction; governs collector current via h_FE.
C (Collector)	Output current terminal	Typically tied to load and supply rail; voltage swing limited by V_CEO and thermal constraints.

Key Features

Feature	Design Value
High h_FE consistency	Guaranteed 120–270 range at standard test conditions supports repeatable bias design without trimming.
Low V_CE(sat)	≤ −0.15 V enables efficient switching in battery-powered logic interfaces and level translators.
SOT-23 footprint	Standardized 3-pin package allows automated placement and reflow compatibility with mainstream PCB assembly lines.
Wide operating temperature	Rated from −55 °C to +150 °C supports deployment in automotive cabin modules and industrial control enclosures.

Applications

Audio Preamp Stage	Level Translation Circuit
Use Scenario: Amplifying microphone or sensor output signals prior to ADC sampling in portable audio recorders. IC Role / Device Role / Timing Role: PNP BJT configured in common-emitter topology to provide voltage gain and impedance matching. Use Value: Stable h_FE range and low noise performance ensure consistent signal fidelity across production units.	Use Scenario: Converting 3.3 V logic outputs to interface with legacy 5 V TTL inputs in mixed-voltage microcontroller systems. IC Role / Device Role / Timing Role: Active pull-up switch implementing open-collector emulation with controlled rise time. Use Value: Low V_CE(sat) minimizes voltage offset error, while f_T > 100 MHz ensures clean edge transitions.
Complementary Pair Switch	Load Switch for Sensor Bias
Use Scenario: Forming a Class AB output stage with matched NPN 2SC5658-H in compact wearable audio amplifiers. IC Role / Device Role / Timing Role: PNP half of push-pull pair delivering current during negative half-cycle of AC waveform. Use Value: Matched thermal characteristics and h_FE symmetry reduce crossover distortion and improve THD performance.	Use Scenario: Enabling/disabling bias current to analog temperature sensors in energy-constrained IoT nodes. IC Role / Device Role / Timing Role: High-side switch controlling power delivery to sensor's reference leg. Use Value: 200 mW power rating and low standby leakage support ultra-low quiescent current operation.

Audio Preamp Stage

Level Translation Circuit

Use Scenario: Amplifying microphone or sensor output signals prior to ADC sampling in portable audio recorders.

IC Role / Device Role / Timing Role: PNP BJT configured in common-emitter topology to provide voltage gain and impedance matching.

Use Value: Stable h_FE range and low noise performance ensure consistent signal fidelity across production units.

Use Scenario: Converting 3.3 V logic outputs to interface with legacy 5 V TTL inputs in mixed-voltage microcontroller systems.

IC Role / Device Role / Timing Role: Active pull-up switch implementing open-collector emulation with controlled rise time.

Use Value: Low V_CE(sat) minimizes voltage offset error, while f_T > 100 MHz ensures clean edge transitions.

Complementary Pair Switch

Load Switch for Sensor Bias

Use Scenario: Forming a Class AB output stage with matched NPN 2SC5658-H in compact wearable audio amplifiers.

IC Role / Device Role / Timing Role: PNP half of push-pull pair delivering current during negative half-cycle of AC waveform.

Use Value: Matched thermal characteristics and h_FE symmetry reduce crossover distortion and improve THD performance.

Use Scenario: Enabling/disabling bias current to analog temperature sensors in energy-constrained IoT nodes.

IC Role / Device Role / Timing Role: High-side switch controlling power delivery to sensor's reference leg.

Use Value: 200 mW power rating and low standby leakage support ultra-low quiescent current operation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP BJT amplification and switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SA1774-TL-E	Higher V_CEO (60 V), lower h_FE (82–180), same SOT-23 package	Better suited for higher-voltage industrial controls where margin above 50 V is required	Select when system rail exceeds 45 V or tighter thermal management is needed due to higher P_D rating
MMBT2907ALT1G	Same V_CEO (60 V), wider h_FE range (100–300), slightly higher f_T (200 MHz)	Preferred for high-speed switching or where broader gain tolerance is acceptable	Choose when interoperability with existing MMBT2907A-based designs is prioritized over exact h_FE match

Compared with 2SA2126-H, 2SA1774-TL-E offers greater voltage headroom but reduced gain consistency, while MMBT2907ALT1G provides higher speed and broader gain spread - both require validation of bias network stability under target operating conditions.

Availability

2SA2126-H is available at Aetrix Electronics and suitable for audio preamplification, level translation, and complementary switching applications requiring stable component supply, consistent h_FE binning, and SOT-23 footprint compatibility.

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

The 2SA2126-H belongs to onsemi's general-purpose bipolar transistor product line, engineered for cost-sensitive, space-constrained designs where predictable DC gain, low saturation voltage, and robust thermal performance are essential.

FAQ

What is the maximum collector-emitter voltage rating for the 2SA2126-H?

The 2SA2126-H has a maximum collector-emitter voltage (V_CEO) rating of 50 V. This value represents the highest voltage that can be applied between collector and emitter with the base open, beyond which avalanche breakdown may occur. Designers must ensure operating V_CE remains below this limit under all conditions, including transients, to maintain reliability of the 2SA2126-H.

Does the 2SA2126-H have a guaranteed h_FE range, and at what test conditions?

Yes, the 2SA2126-H guarantees an h_FE range of 120 to 270 when tested at I_C = 2 mA and V_CE = 2 V. This specification is verified per onsemi's production test flow and applies to all units shipped as 2SA2126-H. The gain range supports deterministic biasing in linear amplifier designs without requiring post-manufacturing sorting or adjustment.

Is the 2SA2126-H suitable for use in high-frequency amplifier circuits?

The 2SA2126-H has a transition frequency (f_T) of 180 MHz, making it suitable for small-signal amplification up to mid-VHF frequencies. However, it is not intended for RF power amplification or GHz-range applications. For audio and low-speed data interface circuits - such as microphone preamps or logic-level shifters - the 2SA2126-H delivers stable gain and phase response, confirmed in onsemi's characterization data for the 2SA2126-H.

What is the package type and thermal resistance of the 2SA2126-H?

The 2SA2126-H uses the SOT-23 (TO-236AB) surface-mount package. Its junction-to-ambient thermal resistance (R_θJA) is 625 °C/W under standard JEDEC PCB mounting conditions. This value implies significant thermal derating above 25 °C ambient - for example, maximum power dissipation drops to ~120 mW at 70 °C ambient. Proper PCB copper area and airflow should be considered in thermal design for the 2SA2126-H.

Can the 2SA2126-H be used as a direct replacement for the 2SA1037 in existing designs?

No, the 2SA2126-H is not a direct replacement for the 2SA1037. While both are PNP BJTs in SOT-23 packages, the 2SA1037 has V_CEO = 60 V and h_FE = 120–270 at I_C = 10 mA - differing in test current and voltage rating. Substituting the 2SA2126-H into a 2SA1037 design requires verification of bias point stability, saturation margin, and transient voltage compliance. Always validate circuit behavior with the actual 2SA2126-H parameters before integration.

2SA2126-H Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

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-H FAQ

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

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

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

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

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

Note: Certain payment methods may incur a processing fee.

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

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

Once your 2SA2126-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 2SA2126-H?

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

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

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

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

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

Return procedure for 2SA2126-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…