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

onsemi MMBT4124LT1

Name: MMBT4124LT1
Brand: onsemi
SKU: MMBT4124LT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBT4124LT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: MMBT4124LT1.pdf

Description:: TRANS NPN 25V 0.2A SOT23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MMBT4124LT1 from onsemi is an NPN silicon general-purpose transistor in SOT-23 package, rated for 25 V_CEO, 200 mA continuous collector current, and 300 MHz transition frequency (f_T). It serves as a low-power switching or amplification device in signal routing, level translation, and biasing circuits within consumer electronics and industrial control modules.

For engineers reviewing the MMBT4124LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include V_CE(sat) ≤ 0.3 V at I_C/I_B = 10, h_FE range of 120–360 at 2 mA, and thermal resistance R_JA = 556 °C/W on FR-5 board - critical for compact PCB layouts with moderate power dissipation.

Technical Context

This NPN bipolar junction transistor operates in active, saturation, and cutoff regions with verified DC current gain (h_FE) spanning 120–360 across 2–50 mA collector currents and V_CE = 1.0 V. Its f_T = 300 MHz confirms suitability for RF front-end buffering and audio-frequency amplification up to ~100 kHz small-signal bandwidth.

Thermal performance is defined for two mounting conditions: 225 W dissipation on FR-5 board (derating 1.8 mW/°C above 25°C) and 300 W on alumina substrate (derating 2.4 mW/°C), with corresponding R_JA values of 556 °C/W and 417 °C/W - enabling thermal design flexibility based on PCB material and layout.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 V - Maximum safe collector-emitter voltage before breakdown; defines rail compatibility in 3.3 V/5 V logic-level switching.
I_C (continuous)	200 mA - Sustained collector current handling; supports relay drivers, LED loads, and sensor interface stages.
f_T	300 MHz - Transition frequency at I_C = 10 mA, V_CE = 20 V; enables stable small-signal amplification up to mid-VHF band.
V_CE(sat)	≤ 0.3 V at I_C = 50 mA, I_B = 5 mA - Low saturation voltage minimizes conduction loss in digital switching applications.
h_FE	120–360 at I_C = 2 mA, V_CE = 1 V - Wide DC gain range allows predictable biasing without tight tolerance resistors.
C_ibo	≤ 8.0 pF at V_EB = 0.5 V - Input capacitance impacts high-frequency input impedance and Miller effect in amplifier stages.

Pinout & Package

SOT-23 (TO-236) surface-mount package, 2.90 × 1.30 × 1.00 mm, 3-pin configuration per Style 6 marking diagram.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Current-controlled input node; requires series resistor to limit base drive and ensure saturation under load.
2	Emitter	Common reference terminal; connected to ground or low-side return path in common-emitter configurations.
3	Collector	Output current sink; interfaces with load (e.g., LED anode, relay coil) tied to positive supply rail.

Key Features

Feature	Design Value
Pb-free, RoHS-compliant construction	Meets EU Directive 2011/65/EU; eliminates lead-based solder compatibility concerns in modern assembly lines.
Low V_CE(sat) at medium current	0.3 V max at 50 mA ensures <15 mW conduction loss - critical for battery-powered sensor nodes.
High f_T with low C_cb	300 MHz f_T and 4.0 pF C_cb support stable gain in broadband preamplifier stages up to 50 MHz.
Wide operating temperature range	−55°C to +150°C junction storage enables use in automotive under-hood and industrial motor-control environments.

Applications

LED Driver Circuit	Microcontroller GPIO Expander
Use Scenario: Driving discrete indicator LEDs from 3.3 V microcontroller outputs with current limiting via base resistor. IC Role / Device Role / Timing Role: NPN switch configured in common-emitter mode, sinking LED cathode current to ground. Use Value: V_CE(sat) ≤ 0.3 V ensures >90% of supply voltage reaches LED forward drop, maximizing brightness efficiency.	Use Scenario: Level-shifting and current boosting for MCU pins unable to source/sink >20 mA directly. IC Role / Device Role / Timing Role: Signal buffer and current amplifier between low-drive GPIO and external peripherals (e.g., optocouplers, small relays). Use Value: h_FE ≥ 120 at 2 mA enables reliable switching with minimal base current overhead - preserving MCU pin drive capability.
Audio Signal Preamp Stage	Power Supply Enable Switch
Use Scenario: Low-noise voltage amplification of microphone or sensor signals prior to ADC sampling. IC Role / Device Role / Timing Role: Common-emitter small-signal amplifier biased in active region with emitter degeneration. Use Value: NF ≤ 5.0 dB at I_C = 100 μA and R_S = 1 kΩ supports clean analog signal conditioning in portable audio devices.	Use Scenario: Controlling enable inputs of DC-DC converters or LDOs using logic-level signals from system controllers. IC Role / Device Role / Timing Role: High-side or low-side enable switch isolating power domain activation timing. Use Value: Fast switching times (t_d, t_r, t_f < 100 ns at I_C/I_B = 10) ensure precise sequencing in multi-rail power systems.

LED Driver Circuit

Microcontroller GPIO Expander

Use Scenario: Driving discrete indicator LEDs from 3.3 V microcontroller outputs with current limiting via base resistor.

IC Role / Device Role / Timing Role: NPN switch configured in common-emitter mode, sinking LED cathode current to ground.

Use Value: V_CE(sat) ≤ 0.3 V ensures >90% of supply voltage reaches LED forward drop, maximizing brightness efficiency.

Use Scenario: Level-shifting and current boosting for MCU pins unable to source/sink >20 mA directly.

IC Role / Device Role / Timing Role: Signal buffer and current amplifier between low-drive GPIO and external peripherals (e.g., optocouplers, small relays).

Use Value: h_FE ≥ 120 at 2 mA enables reliable switching with minimal base current overhead - preserving MCU pin drive capability.

Audio Signal Preamp Stage

Power Supply Enable Switch

Use Scenario: Low-noise voltage amplification of microphone or sensor signals prior to ADC sampling.

IC Role / Device Role / Timing Role: Common-emitter small-signal amplifier biased in active region with emitter degeneration.

Use Value: NF ≤ 5.0 dB at I_C = 100 μA and R_S = 1 kΩ supports clean analog signal conditioning in portable audio devices.

Use Scenario: Controlling enable inputs of DC-DC converters or LDOs using logic-level signals from system controllers.

IC Role / Device Role / Timing Role: High-side or low-side enable switch isolating power domain activation timing.

Use Value: Fast switching times (t_d, t_r, t_f < 100 ns at I_C/I_B = 10) ensure precise sequencing in multi-rail power systems.

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
PN2222A	TO-92 package; higher V_CEO = 40 V; lower f_T = 300 kHz typical; larger footprint.	Through-hole assembly only; unsuitable for space-constrained SMT designs.	Select when through-hole prototyping or legacy board repair is required and higher voltage margin is needed.
BC847B	SOT-23 package; same pinout (Style 6); V_CEO = 45 V; h_FE = 200–450 at 2 mA; slightly higher C_ibo = 12 pF.	Higher voltage rating and tighter h_FE binning support more deterministic biasing in precision analog stages.	Prefer for new designs requiring extended voltage headroom or improved gain consistency across production lots.

Compared with PN2222A and BC847B, the MMBT4124LT1 offers optimal balance of SMT compatibility, 25 V rating, and 300 MHz f_T - making it ideal for cost-sensitive, space-limited digital switching where moderate RF performance is beneficial but not primary.

Availability

MMBT4124LT1 is available at Aetrix Electronics and suitable for LED driver circuits, microcontroller GPIO expansion, and audio preamplifier stages requiring stable component supply and consistent parametric performance across production volumes.

Supply support for MMBT4124LT1 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, sensors, and connectivity solutions for automotive, industrial, and consumer markets.

The MMBT4124LT1 belongs to onsemi's general-purpose bipolar transistor product line, engineered for reliable low-voltage switching and amplification in cost-sensitive, high-volume applications where SMT scalability and RoHS compliance are mandatory.

FAQ

What is the maximum continuous collector current rating for the MMBT4124LT1?

The MMBT4124LT1 has a maximum continuous collector current (I_C) rating of 200 mA at T_A = 25°C on FR-5 board. Derating applies above 25°C at 1.8 mW/°C. This rating supports driving small relays, LEDs, and logic-level interface loads without forced-air cooling in standard PCB layouts.

Does the MMBT4124LT1 have a documented pinout configuration for SOT-23?

Yes, the MMBT4124LT1 uses SOT-23 Style 6 pinout: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This configuration is confirmed in the official onsemi datasheet (Publication Order Number MMBT4124LT1/D, Rev. 4, October 2024) and matches industry-standard NPN SOT-23 layouts for seamless PCB footprint reuse.

What is the typical noise figure of the MMBT4124LT1 in audio-frequency amplification?

The MMBT4124LT1 exhibits a noise figure (NF) of ≤ 5.0 dB at I_C = 100 μA, V_CE = 5.0 V, R_S = 1.0 kΩ, and f = 1.0 kHz. This value makes the MMBT4124LT1 suitable for low-noise preamplifier stages in microphone interfaces and sensor signal conditioning where signal integrity is critical.

Is the MMBT4124LT1 RoHS-compliant and halogen-free?

Yes, the MMBT4124LT1 is explicitly marked Pb-free, halogen-free/BFR-free, and RoHS-compliant per EU Directive 2011/65/EU. The "G" suffix in MMBT4124LT1G denotes this compliance, and the device meets JEDEC J-STD-609A Class 1 moisture sensitivity requirements for standard SMT reflow processes.

How does the MMBT4124LT1's f_T compare to other general-purpose SOT-23 transistors?

The MMBT4124LT1 delivers f_T = 300 MHz at I_C = 10 mA and V_CE = 20 V - significantly higher than standard equivalents like BC847B (f_T ≈ 100 MHz) and PN2222A (f_T ≈ 300 kHz). This enables the MMBT4124LT1 to maintain usable gain in RF buffer and broadband amplifier roles where others roll off prematurely.

MMBT4124LT1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

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:: -

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

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

Power - Max:: 225 mW

Frequency - Transition:: 300MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3 (TO-236)

MMBT4124LT1 FAQ

1.How can I place an order for MMBT4124LT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBT4124LT1 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 MMBT4124LT1 reliable?

The price and inventory of MMBT4124LT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBT4124LT1 is usually 5 days.

3.What payment methods are accepted for MMBT4124LT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBT4124LT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBT4124LT1?

MMBT4124LT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBT4124LT1 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 MMBT4124LT1?

For technical support, including MMBT4124LT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBT4124LT1 requirements.

6.How does Aetrix verify that MMBT4124LT1 is sourced from the original manufacturer or authorized distributors?

All MMBT4124LT1 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 MMBT4124LT1 meets industry standards.

7.What is the process for return or replacement of MMBT4124LT1?

All MMBT4124LT1 units undergo pre-shipment inspection (PSI). If there is an issue with MMBT4124LT1, 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 MMBT4124LT1 part is unused and in its original packaging.

Return procedure for MMBT4124LT1:

1.Submit a request within 90 days.

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

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