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 2N4124G

Name: 2N4124G
Brand: onsemi
SKU: 2N4124G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 2N4124G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body

Datasheet:: 2N4124G.pdf

Description:: TRANS NPN 25V 0.2A TO92

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:5,016

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

Product details

Overview

2N4124G from onsemi is an NPN silicon general-purpose transistor in TO-92 package, rated for V_CEO = 25 V, I_C = 200 mA, and P_D = 625 mW at T_A = 25°C, with h_FE = 25–60 at I_C = 50 mA and f_T = 300 MHz - commonly used in low-power amplification and switching circuits in consumer electronics and industrial control interfaces.

For engineers reviewing the 2N4124G datasheet, pinout, applications, or equivalent options, key selection considerations include its V_CEO/V_CBO ratings, DC current gain range at defined bias points, saturation voltage under 50 mA/5 mA drive, thermal resistance (R_JA = 200°C/W), and Pb-free TO-92 mechanical compatibility.

Technical Context

The 2N4124G operates as a discrete bipolar junction transistor with fixed NPN polarity, optimized for linear amplification and saturated switching in low-voltage (<25 V) analog and digital signal paths. Its h_FE variation across I_C = 2–50 mA and temperature (−55°C to +150°C) is documented in Figure 9, and small-signal parameters (h_fe, C_ibo, C_cb) are specified at 1 kHz and 100 MHz.

Thermal design relies on R_JA = 200°C/W (ambient) and R_JC = 83.3°C/W (case), with derating of 5.0 mW/°C above 25°C ambient. Noise figure is 5.0 dB at I_C = 100 μA, V_CE = 5 V, R_S = 1 kΩ, f = 1 kHz - confirming suitability for low-noise preamplifier stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 Vdc - maximum collector-emitter voltage before breakdown; defines safe operating voltage headroom in switching applications.
I_C (max)	200 mAdc - continuous collector current limit; sets upper bound for load-driving capability in amplifier or switch configurations.
h_FE	25–60 at I_C = 50 mA, V_CE = 1 V - usable DC current gain range for predictable base drive sizing in saturation-critical designs.
f_T	300 MHz - transition frequency at I_C = 10 mA, V_CE = 20 V; supports RF amplification up to ~100 MHz with stable gain margin.
V_CE(sat)	≤0.3 V at I_C = 50 mA, I_B = 5 mA - low saturation voltage minimizes power loss and heating in digital logic interface or relay driver use cases.
R_JA	200°C/W - thermal resistance from junction to ambient; requires ≥0.5 cm² PCB copper pour for sustained 625 mW dissipation at room temperature.

Pinout & Package

2N4124G is housed in a Pb-free TO-92 (Case 29-11) plastic package with straight or bent leads, standardized for through-hole mounting and manual assembly. Dimensions comply with ANSI Y14.5M and ASME Y14.5M tolerancing; lead pitch is 2.54 mm (0.100 inch).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit path for majority carriers	Connected to circuit ground or low-impedance return; base-emitter junction forward-biased during conduction.
2 (Base)	Control terminal for minority carrier injection	Receives current-limited drive (e.g., via 1–10 kΩ resistor); determines collector current magnitude via h_FE.
3 (Collector)	Current entry path for majority carriers	Connected to load and supply rail; collector-emitter voltage swing must stay ≤25 V to avoid avalanche failure.

Key Features

Feature	Design Value
Pb-free TO-92 packaging	Complies with RoHS Directive 2011/65/EU; eliminates lead contamination risk in reflow and hand-soldering processes.
Low V_CE(sat) (≤0.3 V)	Reduces conduction loss in high-duty-cycle switching applications such as LED drivers and logic-level translators.
f_T = 300 MHz	Enables stable small-signal amplification in IF stages of AM/FM receivers and sensor signal conditioning up to 100 MHz.
Wide T_J range (−55°C to +150°C)	Supports operation in automotive engine compartments, industrial PLC I/O modules, and outdoor equipment without derating.
Low noise figure (5.0 dB)	Validated at audio frequencies with 1 kΩ source impedance; suitable for microphone preamps and sensor front-end amplifiers.

Applications

Audio Pre-amplifier Stage	Low-Voltage Switch Driver
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in portable audio devices. IC Role / Device Role / Timing Role: Discrete NPN transistor configured in common-emitter topology for voltage gain and impedance matching. Use Value: 5.0 dB noise figure and h_fe ≥200 at I_C = 2 mA ensure high signal-to-noise ratio and stable gain across battery voltage variations.	Use Scenario: Driving 12 V relays or indicator LEDs from 3.3 V or 5 V microcontroller GPIO pins. IC Role / Device Role / Timing Role: Saturated switch controlling load current with minimal V_CE drop and fast turn-on/turn-off. Use Value: V_CE(sat) ≤0.3 V at I_C/I_B = 10 ensures <15 mW power loss per switch, enabling direct MCU interfacing without level-shifting.
RF Intermediate Frequency Amplifier	Industrial Sensor Interface
Use Scenario: Boosting 455 kHz or 10.7 MHz IF signals in AM/FM radio receivers before demodulation. IC Role / Device Role / Timing Role: Small-signal amplifier biased for Class-A operation with emitter degeneration for linearity. Use Value: f_T = 300 MHz and h_fe = 120 at 10 mA provide >20 dB gain margin at 10 MHz, minimizing distortion in narrowband IF chains.	Use Scenario: Converting 4–20 mA current-loop sensor outputs to voltage levels for ADC input in PLC analog input modules. IC Role / Device Role / Timing Role: Transimpedance amplifier stage with emitter-follower output buffering. Use Value: R_JA = 200°C/W and T_J rating to +150°C allow reliable operation in unventilated industrial enclosures with ambient up to 85°C.

Audio Pre-amplifier Stage

Low-Voltage Switch Driver

Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in portable audio devices.

IC Role / Device Role / Timing Role: Discrete NPN transistor configured in common-emitter topology for voltage gain and impedance matching.

Use Value: 5.0 dB noise figure and h_fe ≥200 at I_C = 2 mA ensure high signal-to-noise ratio and stable gain across battery voltage variations.

Use Scenario: Driving 12 V relays or indicator LEDs from 3.3 V or 5 V microcontroller GPIO pins.

IC Role / Device Role / Timing Role: Saturated switch controlling load current with minimal V_CE drop and fast turn-on/turn-off.

Use Value: V_CE(sat) ≤0.3 V at I_C/I_B = 10 ensures <15 mW power loss per switch, enabling direct MCU interfacing without level-shifting.

RF Intermediate Frequency Amplifier

Industrial Sensor Interface

Use Scenario: Boosting 455 kHz or 10.7 MHz IF signals in AM/FM radio receivers before demodulation.

IC Role / Device Role / Timing Role: Small-signal amplifier biased for Class-A operation with emitter degeneration for linearity.

Use Value: f_T = 300 MHz and h_fe = 120 at 10 mA provide >20 dB gain margin at 10 MHz, minimizing distortion in narrowband IF chains.

Use Scenario: Converting 4–20 mA current-loop sensor outputs to voltage levels for ADC input in PLC analog input modules.

IC Role / Device Role / Timing Role: Transimpedance amplifier stage with emitter-follower output buffering.

Use Value: R_JA = 200°C/W and T_J rating to +150°C allow reliable operation in unventilated industrial enclosures with ambient up to 85°C.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N4123G	V_CEO = 30 V (vs. 25 V), h_FE = 50–120 at I_C = 2 mA, f_T = 250 MHz	Better voltage headroom but lower f_T; preferred where V_CE may exceed 25 V but RF performance is secondary	Select 2N4123G when higher breakdown margin is required and gain uniformity at low I_C is critical.
MPS6518	V_CEO = 25 V, h_FE = 30–150 at I_C = 10 mA, f_T = 250 MHz, R_JA = 200°C/W	Near-identical voltage/current ratings but wider h_FE spread; same thermal profile and TO-92 footprint	MPS6518 offers broader h_FE tolerance for cost-sensitive production where binning is impractical.

Compared with 2N4124G, the 2N4123G provides higher V_CEO for improved safety margin in variable-supply systems, while the MPS6518 delivers extended h_FE range for consistent biasing across manufacturing lots - both retain TO-92 compatibility and thermal behavior.

Availability

2N4124G is available at Aetrix Electronics and suitable for audio pre-amplifier stages, low-voltage switch drivers, RF intermediate frequency amplifiers, industrial sensor interfaces, and general-purpose analog signal conditioning requiring stable component supply and RoHS-compliant packaging.

Supply support for 2N4124G 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 management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2N4124G belongs to onsemi's legacy general-purpose transistor product line, designed for cost-effective, reliable amplification and switching in non-critical analog and digital circuits across broad industrial and consumer applications.

FAQ

What is the maximum collector-emitter voltage rating for the 2N4124G?

The 2N4124G has a maximum collector-emitter voltage (V_CEO) rating of 25 Vdc, verified per onsemi's datasheet under test condition I_C = 1.0 mAdc and I_E = 0. Exceeding this voltage risks avalanche breakdown and permanent device damage. Designers should maintain at least 20% margin below 25 V in worst-case operating conditions for long-term reliability of the 2N4124G.

Does the 2N4124G support Pb-free soldering processes?

Yes, the 2N4124G is explicitly marked as a Pb-free package in onsemi's documentation and conforms to RoHS Directive 2011/65/EU. Its TO-92 body uses lead-free molding compound and termination plating, supporting standard reflow profiles (J-STD-020) and hand-soldering without lead contamination concerns - a confirmed specification for the 2N4124G.

What is the typical DC current gain (h_FE) range for the 2N4124G at 50 mA collector current?

The 2N4124G exhibits a DC current gain (h_FE) range of 25 to 60 when tested at I_C = 50 mAdc and V_CE = 1.0 Vdc, as specified in the "ON CHARACTERISTICS" table of the official datasheet. This range reflects unit-to-unit variation and must be accounted for in base resistor calculations for the 2N4124G to ensure robust saturation or linear operation.

Can the 2N4124G be used in RF amplifier applications?

Yes, the 2N4124G is characterized with f_T = 300 MHz at I_C = 10 mAdc and V_CE = 20 Vdc, making it suitable for RF amplification up to approximately 100 MHz. Its documented C_ibo = 8.0 pF and C_cb = 4.0 pF support stable matching network design - a verified RF capability for the 2N4124G in IF and low-band VHF stages.

What is the thermal resistance from junction to ambient (R_JA) for the 2N4124G?

The 2N4124G has a thermal resistance from junction to ambient (R_JA) of 200°C/W when mounted on a standard FR-4 PCB with no added copper pour, per onsemi's thermal characteristics table. This value assumes natural convection and defines the temperature rise per milliwatt dissipated - a critical parameter for thermal management of the 2N4124G in enclosed or high-ambient environments.

2N4124G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 200 mA

Voltage - Collector Emitter Breakdown (Max):: 25 V

Vce Saturation (Max) @ Ib, Ic:: 300mV @ 5mA, 50mA

Current - Collector Cutoff (Max):: 50nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 120 @ 2mA, 1V

Power - Max:: 625 mW

Frequency - Transition:: 300MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

2N4124G FAQ

1.How can I place an order for 2N4124G through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N4124G 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 2N4124G reliable?

The price and inventory of 2N4124G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N4124G is usually 5 days.

3.What payment methods are accepted for 2N4124G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N4124G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N4124G?

2N4124G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N4124G 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 2N4124G?

For technical support, including 2N4124G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N4124G requirements.

6.How does Aetrix verify that 2N4124G is sourced from the original manufacturer or authorized distributors?

All 2N4124G 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 2N4124G meets industry standards.

7.What is the process for return or replacement of 2N4124G?

All 2N4124G units undergo pre-shipment inspection (PSI). If there is an issue with 2N4124G, 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 2N4124G part is unused and in its original packaging.

Return procedure for 2N4124G:

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…