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

onsemi 2SC4081RT1G

Name: 2SC4081RT1G
Brand: onsemi
SKU: 2SC4081RT1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SC4081RT1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: SC-70, SOT-323

Datasheet:: 2SC4081RT1G.pdf

Description:: TRANS NPN 50V 0.1A SC70-3

Quantity:: RFQ Add To RFQ list

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Inventory:3,495

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Product details

Overview

2SC4081RT1G from onsemi is an NPN general-purpose amplifier transistor in SC-70 (SOT-323) surface-mount package, rated for V_(BR)CEO = 50 V, I_C = 100 mA continuous, and h_FE = 180–390 at I_C = 2 mA. It delivers low V_CE(sat) ≤ 0.5 V and supports audio preamplifier, signal switching, and sensor interface circuits in space-constrained consumer and industrial PCBs.

For engineers reviewing the 2SC4081RT1G datasheet, pinout, applications, or equivalent options, key selection criteria include its verified h_FE range, SC-70 thermal performance (P_D = 200 mW), moisture sensitivity level 1 handling, and Pb-free compliance per J-STD-020.

Technical Context

This discrete NPN bipolar junction transistor operates in linear amplification and active switching modes. Its base-emitter junction withstands up to 7.0 V, collector-base up to 60 V, and it sustains peak pulsed current of 200 mA with pulse width ≤ 300 µs and duty cycle ≤ 2%.

The device exhibits guaranteed DC current gain between 180 and 390 under standardized test conditions (V_CE = 6.0 V, I_C = 2.0 mA), and maintains ICEO ≤ 0.1 mA at V_CE = 10 V and TA = 25°C - critical for stable biasing in low-power analog stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_(BR)CEO	50 V - Maximum safe collector-emitter voltage before breakdown; defines upper rail limit in amplifier stages
I_C (continuous)	100 mA - Continuous collector current rating; sets max load drive capability in small-signal switching
h_FE	180–390 - Confirmed DC current gain range at 2 mA collector current; enables predictable bias design
V_CE(sat)	≤ 0.5 V - Saturation voltage at I_C = 100 mA / I_B = 10 mA; ensures low conduction loss in switch mode
P_D	200 mW - Max power dissipation at T_A = 25°C; determines thermal derating margin on FR-4 PCB
T_J max	150°C - Absolute maximum junction temperature; constrains ambient operating envelope in sealed enclosures

Pinout & Package

Package: SC-70 (SOT-323), 3-pin surface-mount plastic case (Case 419), moisture sensitivity level 1, Pb-free compliant.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control electrode; requires current-limited drive (I_B ≤ 10 mA typical) to saturate or bias transistor
2	Emiter	Common reference terminal; connects to ground or emitter resistor in common-emitter configuration
3	Collector	Output/current-sink terminal; routes amplified or switched current to load or next stage

Key Features

Feature	Design Value
Pb-free packaging	RoHS-compliant construction with no lead content; meets JEDEC J-STD-020 MSL 1 reflow profile
Low saturation voltage	V_CE(sat) ≤ 0.5 V at I_C/I_B = 100/10 mA - reduces power loss and self-heating in switching applications
High current gain consistency	h_FE min/max spread of 180–390 - enables stable DC bias without individual trimming in production
Thermal robustness	Rated for T_J up to 150°C and T_stg from −55°C to +150°C - suitable for automotive under-hood and industrial control environments

Applications

Audio Preamp Stage	Sensor Signal Amplifier
Use Scenario: Low-noise voltage amplification of microphone or piezoelectric sensor output in portable audio devices. IC Role / Device Role / Timing Role: NPN small-signal amplifier configured in common-emitter topology with emitter degeneration. Use Value: High h_FE (180–390) ensures sufficient gain at low quiescent current (I_C ≈ 2 mA), minimizing battery drain while maintaining SNR.	Use Scenario: Amplifying weak analog signals from temperature, pressure, or motion sensors in IoT edge nodes. IC Role / Device Role / Timing Role: Discrete transconductance amplifier stage interfacing high-impedance sensor outputs to ADC input buffers. Use Value: Verified V_(BR)EBO = 7.0 V prevents base-emitter junction breakdown during ESD-prone sensor cable coupling.
LED Driver Switch	Logic-Level Interface
Use Scenario: Driving indicator LEDs or low-current optocouplers from microcontroller GPIO pins. IC Role / Device Role / Timing Role: Saturated NPN switch controlling LED anode current path with grounded cathode. Use Value: V_CE(sat) ≤ 0.5 V ensures >90% LED forward voltage utilization and minimal thermal rise at 20–100 mA loads.	Use Scenario: Level-shifting 3.3 V logic signals to 5 V or higher rails in mixed-voltage embedded systems. IC Role / Device Role / Timing Role: Active pull-up/pull-down element translating TTL/CMOS logic states across voltage domains. Use Value: Guaranteed V_(BR)CBO = 60 V allows safe operation with 5 V, 12 V, or 24 V supply rails without clamping diodes.

Audio Preamp Stage

Sensor Signal Amplifier

Use Scenario: Low-noise voltage amplification of microphone or piezoelectric sensor output in portable audio devices.

IC Role / Device Role / Timing Role: NPN small-signal amplifier configured in common-emitter topology with emitter degeneration.

Use Value: High h_FE (180–390) ensures sufficient gain at low quiescent current (I_C ≈ 2 mA), minimizing battery drain while maintaining SNR.

Use Scenario: Amplifying weak analog signals from temperature, pressure, or motion sensors in IoT edge nodes.

IC Role / Device Role / Timing Role: Discrete transconductance amplifier stage interfacing high-impedance sensor outputs to ADC input buffers.

Use Value: Verified V_(BR)EBO = 7.0 V prevents base-emitter junction breakdown during ESD-prone sensor cable coupling.

LED Driver Switch

Logic-Level Interface

Use Scenario: Driving indicator LEDs or low-current optocouplers from microcontroller GPIO pins.

IC Role / Device Role / Timing Role: Saturated NPN switch controlling LED anode current path with grounded cathode.

Use Value: V_CE(sat) ≤ 0.5 V ensures >90% LED forward voltage utilization and minimal thermal rise at 20–100 mA loads.

Use Scenario: Level-shifting 3.3 V logic signals to 5 V or higher rails in mixed-voltage embedded systems.

IC Role / Device Role / Timing Role: Active pull-up/pull-down element translating TTL/CMOS logic states across voltage domains.

Use Value: Guaranteed V_(BR)CBO = 60 V allows safe operation with 5 V, 12 V, or 24 V supply rails without clamping diodes.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN small-signal amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT4401LT1G	Higher I_C = 600 mA, lower h_FE min = 100, same SC-70 package	Better suited for higher-current switching; less gain stability at low I_C	Select when driving >150 mA loads; verify bias network for reduced h_FE spread
BC847BW	Same h_FE range (200–450), V_(BR)CEO = 45 V, slightly higher V_CE(sat) (≤ 0.65 V)	Narrower voltage margin in 50 V rail designs; acceptable for ≤45 V systems	Choose for European supply chains where BC847 series is preferred; confirm V_(BR)CEO margin vs system max voltage

Compared with 2SC4081RT1G, MMBT4401LT1G offers higher current capacity but looser gain control, while BC847BW provides tighter h_FE tolerance at reduced voltage rating - both require layout verification for thermal and routing compatibility despite identical SC-70 footprint.

Availability

2SC4081RT1G is available at Aetrix Electronics and suitable for audio preamplifiers, sensor signal conditioning, and LED driver circuits requiring stable component supply, RoHS compliance, and MSL-1 handling.

Supply support for 2SC4081RT1G 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, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2SC4081RT1G belongs to onsemi's general-purpose bipolar transistor product line, engineered for cost-sensitive, space-constrained analog and switching functions in high-volume consumer and industrial electronics.

FAQ

What is the maximum collector-emitter voltage rating for the 2SC4081RT1G?

The 2SC4081RT1G has a guaranteed minimum collector-emitter breakdown voltage V_(BR)CEO of 50 Vdc at I_C = 2.0 mAdc and I_B = 0. This rating defines the absolute upper limit for safe operation in common-emitter configurations and must not be exceeded even transiently without external clamping.

Does the 2SC4081RT1G meet RoHS requirements?

Yes, the 2SC4081RT1G is explicitly marked as Pb-free in its ordering information and complies with RoHS Directive 2011/65/EU. The "G" suffix denotes lead-free termination, and the device conforms to JEDEC J-STD-020 moisture sensitivity level 1 for standard reflow processing.

What is the pin configuration of the 2SC4081RT1G in the SC-70 package?

The 2SC4081RT1G uses Style 7 pinout in SC-70 (SOT-323): Pin 1 is Base, Pin 2 is Emitter, and Pin 3 is Collector. This configuration is confirmed in the mechanical case outline diagram (Issue R, 11 OCT 2022) and matches the marking diagram showing "81 M" with pin 1 adjacent to the tab.

What is the DC current gain range of the 2SC4081RT1G under standard test conditions?

The 2SC4081RT1G exhibits a DC current gain (h_FE) range of 180 to 390 when measured at V_CE = 6.0 Vdc and I_C = 2.0 mAdc. This specification is guaranteed across the full production lot and is used to calculate base resistor values for reliable biasing in amplifier and switch designs.

Can the 2SC4081RT1G be used in switching applications?

Yes, the 2SC4081RT1G is qualified for switching use with I_C(P) = 200 mAdc peak and V_CE(sat) ≤ 0.5 V at I_C = 100 mAdc / I_B = 10 mAdc. Its fast turn-on/turn-off characteristics and low saturation voltage make it suitable for low-power digital logic interfaces and LED drivers where efficiency and thermal management are critical.

2SC4081RT1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: SC-70, SOT-323

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

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

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 10mA, 100mA

Current - Collector Cutoff (Max):: 100nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 180 @ 2mA, 6V

Power - Max:: 200 mW

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SC-70-3 (SOT323)

2SC4081RT1G FAQ

1.How can I place an order for 2SC4081RT1G through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SC4081RT1G 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 2SC4081RT1G reliable?

The price and inventory of 2SC4081RT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SC4081RT1G is usually 5 days.

3.What payment methods are accepted for 2SC4081RT1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SC4081RT1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SC4081RT1G?

2SC4081RT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SC4081RT1G 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 2SC4081RT1G?

For technical support, including 2SC4081RT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SC4081RT1G requirements.

6.How does Aetrix verify that 2SC4081RT1G is sourced from the original manufacturer or authorized distributors?

All 2SC4081RT1G 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 2SC4081RT1G meets industry standards.

7.What is the process for return or replacement of 2SC4081RT1G?

All 2SC4081RT1G units undergo pre-shipment inspection (PSI). If there is an issue with 2SC4081RT1G, 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 2SC4081RT1G part is unused and in its original packaging.

Return procedure for 2SC4081RT1G:

1.Submit a request within 90 days.

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

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