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 2N4124_S00Z

Name: 2N4124_S00Z
Brand: onsemi
SKU: 2N4124_S00Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 2N4124_S00Z

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA)

Datasheet:: 2N4124_S00Z.pdf

Description:: TRANS NPN 25V 0.2A TO-92-3

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:5,133

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

Product details

Overview

2N4124_S00Z from Fairchild Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) designed for amplification and switching in low-to-medium power analog and digital circuits. It delivers DC current gain (h_FE) of 120–360 at I_C = 2 mA, supports 100 MHz small-signal bandwidth (f_T), and handles continuous collector current up to 200 mA - commonly used in audio preamplifiers, logic-level translators, and discrete driver stages.

For engineers reviewing the 2N4124_S00Z datasheet, pinout, applications, or equivalent options, key selection criteria include its V_CEO = 25 V rating, low V_CE(sat) = 0.3 V at I_C = 50 mA/I_B = 5 mA, thermal resistance R_θJA = 357 °C/W in SOT-23, and noise figure of 5.0 dB at 10 Hz–15.7 kHz - critical for low-noise signal conditioning and fast-switching control loops.

Technical Context

The 2N4124_S00Z operates as a silicon NPN BJT with epitaxial base construction, optimized for linear amplification and saturated switching. Its f_T = 300 MHz and h_fe = 120–480 (at V_CE = 10 V, I_C = 2 mA) support RF-capable analog stages up to ~100 MHz, while its low C_obo = 4.0 pF and C_ibo = 8.0 pF minimize high-frequency loading.

Thermally, it is rated for T_J = –55°C to +150°C and dissipates 350 mW in SOT-23 (derated at 2.8 mW/°C above 25°C). The device exhibits V_BE(sat) = 0.95 V and NF = 5.0 dB under specified bias conditions - enabling predictable biasing and acceptable SNR in front-end amplifier designs.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 V - maximum safe collector-emitter voltage before breakdown; defines rail headroom in switch/amplifier topologies.
I_C (continuous)	200 mA - usable collector current limit for sustained operation without thermal runaway in PCB-mounted SOT-23.
f_T	300 MHz - unity-gain bandwidth; enables stable small-signal amplification up to ~100 MHz with adequate phase margin.
h_FE	120–360 @ I_C = 2 mA - wide DC current gain range affecting bias stability and stage gain predictability.
V_CE(sat)	0.3 V @ I_C/I_B = 50 mA/5 mA - low saturation voltage reduces conduction loss in switching applications.
NF	5.0 dB @ I_C = 100 µA - quantified noise contribution in low-level signal amplification paths.
R_θJA	357 °C/W - thermal resistance from junction to ambient in SOT-23; determines temperature rise under 350 mW dissipation.

Pinout & Package

2N4124_S00Z is packaged in SOT-23 (TO-236AB), marked "ZC", with standard NPN pinout: Emitter (Pin 1), Base (Pin 2), Collector (Pin 3).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Emitter)	Current sink terminal	Reference node for bias network; connects to ground or emitter degeneration resistor in common-emitter configurations.
Pin 2 (Base)	Control input	Receives drive current to modulate collector current; requires series resistor to limit I_B and ensure saturation or linear operation.
Pin 3 (Collector)	Current source output	Delivers amplified/saturated output current; connects to load or next stage; must observe V_CEO and power limits.

Key Features

Feature	Design Value
High f_T / low capacitance	300 MHz f_T with C_obo = 4.0 pF enables broadband amplification without external compensation.
Low V_CE(sat)	0.3 V saturation voltage minimizes power loss and self-heating in digital switching and relay drivers.
Wide h_FE range	120–360 gain spread accommodates production variation while maintaining functional circuit margins.
Low-noise performance	5.0 dB noise figure at 100 µA supports use in microphone preamps and sensor signal conditioning.

Applications

Audio Preamp Stage	Logic-Level Translator
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling. IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier in common-emitter configuration with emitter degeneration. Use Value: Delivers >20 dB voltage gain with 5.0 dB noise figure and minimal distortion at I_C = 100–500 µA bias points.	Use Scenario: Converting 3.3 V CMOS logic outputs to interface with 5 V TTL inputs in mixed-voltage systems. IC Role / Device Role / Timing Role: Saturated NPN switch operating between cutoff and saturation with <100 ns switching times. Use Value: Achieves reliable level shift using V_CE(sat) ≤ 0.3 V and h_FE ≥ 120 to ensure full saturation with low-drive base current.
Discrete LED Driver	Low-Power Relay Control
Use Scenario: Driving indicator LEDs or low-current optocouplers from MCU GPIO pins with current limiting. IC Role / Device Role / Timing Role: Constant-current switch with base resistor selected for I_C = 20–100 mA per LED string. Use Value: Supports up to 200 mA total collector current while maintaining V_CE(sat) < 0.4 V, reducing heat generation on compact PCBs.	Use Scenario: Activating 5 V or 12 V electromagnetic relays requiring 10–50 mA coil current in industrial I/O modules. IC Role / Device Role / Timing Role: High-gain saturated switch providing galvanic isolation between control logic and relay coil. Use Value: Ensures robust turn-on with h_FE ≥ 60 at I_C = 50 mA, eliminating need for Darlington pairing in space-constrained designs.

Audio Preamp Stage

Logic-Level Translator

Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling.

IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier in common-emitter configuration with emitter degeneration.

Use Value: Delivers >20 dB voltage gain with 5.0 dB noise figure and minimal distortion at I_C = 100–500 µA bias points.

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

IC Role / Device Role / Timing Role: Saturated NPN switch operating between cutoff and saturation with <100 ns switching times.

Use Value: Achieves reliable level shift using V_CE(sat) ≤ 0.3 V and h_FE ≥ 120 to ensure full saturation with low-drive base current.

Discrete LED Driver

Low-Power Relay Control

Use Scenario: Driving indicator LEDs or low-current optocouplers from MCU GPIO pins with current limiting.

IC Role / Device Role / Timing Role: Constant-current switch with base resistor selected for I_C = 20–100 mA per LED string.

Use Value: Supports up to 200 mA total collector current while maintaining V_CE(sat) < 0.4 V, reducing heat generation on compact PCBs.

Use Scenario: Activating 5 V or 12 V electromagnetic relays requiring 10–50 mA coil current in industrial I/O modules.

IC Role / Device Role / Timing Role: High-gain saturated switch providing galvanic isolation between control logic and relay coil.

Use Value: Ensures robust turn-on with h_FE ≥ 60 at I_C = 50 mA, eliminating need for Darlington pairing in space-constrained designs.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT4124	Same die, identical electrical specs, SOT-23 package; marking "ZC" matches 2N4124_S00Z.	No functional difference; direct second-source part with identical qualification and traceability.	Select MMBT4124 when sourcing from alternate distribution channels or requiring standard JEDEC-compliant part number.
BC847B	h_FE = 200–450 (tighter bin), V_CEO = 45 V, f_T = 100 MHz - higher voltage rating but lower bandwidth.	Better suited for 5–12 V rail systems needing extra margin; less optimal for >50 MHz signal paths.	Choose BC847B where V_CEO derating or tighter h_FE tolerance is required, accepting reduced RF capability.

Compared with MMBT4124 and BC847B, the 2N4124_S00Z offers the highest f_T (300 MHz) among the three while maintaining industry-standard SOT-23 footprint and 25 V V_CEO, making it preferred for bandwidth-critical amplification where moderate voltage headroom suffices.

Availability

2N4124_S00Z is available at Aetrix Electronics and suitable for audio preamplifiers, logic-level translators, and discrete LED drivers requiring stable component supply across prototyping, pilot production, and long-lifecycle industrial programs.

Supply support for 2N4124_S00Z 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The 2N4124_S00Z belongs to Fairchild's legacy general-purpose BJT family, engineered for cost-sensitive, high-reliability linear and switching applications in consumer, industrial, and communications equipment.

FAQ

What is the maximum operating temperature for the 2N4124_S00Z?

The 2N4124_S00Z has a specified junction temperature range of –55°C to +150°C. Its maximum operating ambient temperature depends on power dissipation and PCB layout: at 25°C ambient, it can safely dissipate 350 mW in SOT-23; above that, derating is 2.8 mW/°C. Thermal design must ensure T_J stays within limits under worst-case load and airflow conditions. The 2N4124_S00Z datasheet confirms this via R_θJA = 357 °C/W.

Is the 2N4124_S00Z pin-compatible with TO-92 versions of the 2N4124?

No - the 2N4124_S00Z uses the SOT-23 package (3-pin, surface-mount), while through-hole TO-92 versions have different mechanical dimensions, lead spacing, and thermal characteristics. Although both share identical electrical specifications and NPN pinout (E-B-C), PCB layout, reflow profile, and thermal management differ significantly. The 2N4124_S00Z is not a drop-in replacement for TO-92 without board redesign.

What is the typical noise figure of the 2N4124_S00Z and under what conditions is it measured?

The 2N4124_S00Z has a typical noise figure of 5.0 dB, measured at I_C = 100 µA, V_CE = 5.0 V, R_S = 1.0 kΩ, and frequency range 10 Hz to 15.7 kHz. This value reflects its suitability for low-level analog signal amplification where SNR preservation is critical. The 2N4124_S00Z datasheet specifies this condition explicitly in the Small-Signal Characteristics table.

Can the 2N4124_S00Z be used in RF amplifier stages?

Yes - the 2N4124_S00Z has f_T = 300 MHz and low parasitic capacitances (C_obo = 4.0 pF, C_ibo = 8.0 pF), supporting stable small-signal amplification up to ~100 MHz. Its h_fe and output admittance remain usable in VHF front-ends, though matching networks and bias stability must be verified per application. The 2N4124_S00Z is not characterized for >200 MHz large-signal operation or PA use.

What does the "S00Z" suffix indicate in the 2N4124_S00Z part number?

The "S00Z" suffix identifies a specific Fairchild manufacturing variant: "S" denotes SOT-23 packaging, "00" indicates tape-and-reel packaging format, and "Z" corresponds to the die lot and marking code "ZC" laser-etched on the device body. This distinguishes it from TO-92 or bulk-packaged versions. The 2N4124_S00Z is fully electrically equivalent to MMBT4124 per Fairchild documentation.

2N4124_S00Z Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA)

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-92-3

2N4124_S00Z FAQ

1.How can I place an order for 2N4124_S00Z through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N4124_S00Z 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 2N4124_S00Z reliable?

The price and inventory of 2N4124_S00Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N4124_S00Z is usually 5 days.

3.What payment methods are accepted for 2N4124_S00Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N4124_S00Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N4124_S00Z?

2N4124_S00Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N4124_S00Z 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 2N4124_S00Z?

For technical support, including 2N4124_S00Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N4124_S00Z requirements.

6.How does Aetrix verify that 2N4124_S00Z is sourced from the original manufacturer or authorized distributors?

All 2N4124_S00Z 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 2N4124_S00Z meets industry standards.

7.What is the process for return or replacement of 2N4124_S00Z?

All 2N4124_S00Z units undergo pre-shipment inspection (PSI). If there is an issue with 2N4124_S00Z, 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 2N4124_S00Z part is unused and in its original packaging.

Return procedure for 2N4124_S00Z:

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…