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 MMBT3904WT1

Name: MMBT3904WT1
Brand: onsemi
SKU: MMBT3904WT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: MMBT3904WT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: -

Datasheet:: MMBT3904WT1.pdf

Description:: TRANS NPN 40V 200MA SOT323

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:4,843

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

Product details

Overview

MMBT3904WT1 from onsemi is an NPN general-purpose bipolar junction transistor (BJT) in SOT-323 (SC-70) package, rated for 40 V_CEO, 200 mA_C, and 150 mW power dissipation. It delivers DC current gain (h_FE) of 100–300 at I_C = 10 mA, V_CE = 1 V, and exhibits f_T = 300 MHz for RF-amplifier and switching applications in portable audio, sensor interface, and logic-level translation circuits.

For engineers reviewing the MMBT3904WT1 datasheet, pinout, applications, or equivalent options, this page provides verified electrical parameters, thermal limits, switching timing (t_d/t_r/t_s/t_f), saturation behavior (V_CE(sat), V_BE(sat)), and validated alternatives for discrete BJT replacement in low-power surface-mount designs.

Technical Context

The MMBT3904WT1 operates as a silicon NPN BJT optimized for linear amplification and saturated switching in low-voltage, low-current signal paths. Its design supports DC biasing with h_FE ≥ 100 at 10 mA and maintains stable small-signal gain (h_fe = 100–400) across 1 kHz–100 MHz frequencies under V_CE = 10 V conditions.

Thermal performance is defined by R_JA = 833°C/W on FR4 PCB with minimum footprint, enabling operation from −55°C to +150°C junction temperature. Switching behavior includes t_d ≤ 35 ns, t_r ≤ 35 ns, t_s ≤ 200 ns, and t_f ≤ 50 ns under specified test conditions (V_CC = 3 V, I_C/I_B = 10).

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum collector-emitter voltage before breakdown; sets upper rail limit for amplifier or switch operation.
I_C (continuous)	200 mA - Continuous collector current rating; defines max load drive capability without derating.
P_D @ T_A = 25°C	150 mW - Total device power dissipation on standard FR4; determines thermal margin in compact layouts.
h_FE @ I_C = 10 mA	100–300 - DC current gain range at mid-current; ensures predictable base drive sizing for saturation.
f_T	300 MHz - Current-gain bandwidth product; supports RF amplification up to VHF band in low-noise stages.
V_CE(sat) @ I_C/I_B = 10	0.2–0.3 V - Low saturation voltage at 10 mA/1 mA drive; minimizes conduction loss in digital switching.
R_JA	833°C/W - Junction-to-ambient thermal resistance; informs heatsinking requirements on minimal PCB copper.

Pinout & Package

MMBT3904WT1 uses the SC-70 (SOT-323) plastic surface-mount package (Case 419, Style 3), measuring 2.2 mm × 1.35 mm × 0.95 mm, with gull-wing leads for reflow compatibility and space-constrained PCBs.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased junction; requires current-limited drive (typically 1/10 of I_C) to ensure saturation.
2	Emitter	Current return path; connected to ground or low-side reference in common-emitter configurations.
3	Collector	Output current path; ties to load or pull-up resistor; handles full switched/signal current up to 200 mA.

Key Features

Feature	Design Value
Pb-free, Halogen-free, RoHS-compliant	Meets global environmental compliance without derating or process change; suitable for consumer and industrial end-equipment.
SOT-323 (SC-70) footprint	Enables high-density placement on 0.5 mm pitch PCBs; compatible with standard reflow profiles and automated assembly.
V_BE(sat) = 0.65–0.85 V @ I_C = 10 mA	Ensures predictable base drive voltage drop; simplifies bias network design in TTL/CMOS interfacing.
Low C_obo = 4.0 pF & C_ibo = 8.0 pF	Minimizes Miller effect and input loading in high-frequency amplifiers; preserves bandwidth in RF front-ends.
−55°C to +150°C operating range	Supports deployment in automotive under-hood, industrial control, and outdoor sensor nodes without thermal derating.

Applications

Audio Pre-amplifier Stage	LED Driver Switch
Use Scenario: Amplifying weak microphone signals in battery-powered voice recorders before ADC sampling. IC Role / Device Role / Timing Role: NPN BJT configured in common-emitter topology for voltage gain with low noise figure (NF = 5.0 dB @ 1 kHz). Use Value: Delivers >20 dB voltage gain at 10 kHz while maintaining <1% THD due to stable h_FE and low V_CE(sat).	Use Scenario: Driving 20 mA indicator LEDs from 3.3 V GPIO pins in IoT edge nodes. IC Role / Device Role / Timing Role: Saturated switch controlling LED anode connection to V_CC with base driven by microcontroller output. Use Value: Achieves <0.3 V dropout at 20 mA, reducing power loss by 40% vs. higher-V_CE(sat) transistors and extending battery life.
Logic-Level Translator	Current Mirror Reference
Use Scenario: Converting 1.8 V CMOS logic outputs to 5 V levels for legacy peripherals in mixed-voltage systems. IC Role / Device Role / Timing Role: NPN switch in emitter-follower or common-base configuration to shift voltage thresholds without inversion. Use Value: Supports <35 ns propagation delay and <50 ns fall time, preserving signal integrity for 10 MHz digital buses.	Use Scenario: Building matched current sources in precision analog sensor conditioning circuits (e.g., RTD bridges). IC Role / Device Role / Timing Role: Paired MMBT3904WT1 devices in monolithic layout to replicate reference current with <5% mismatch over temperature. Use Value: Leverages tight h_FE distribution and identical thermal coefficients to maintain <0.5% current tracking from −40°C to +85°C.

Audio Pre-amplifier Stage

LED Driver Switch

Use Scenario: Amplifying weak microphone signals in battery-powered voice recorders before ADC sampling.

IC Role / Device Role / Timing Role: NPN BJT configured in common-emitter topology for voltage gain with low noise figure (NF = 5.0 dB @ 1 kHz).

Use Value: Delivers >20 dB voltage gain at 10 kHz while maintaining <1% THD due to stable h_FE and low V_CE(sat).

Use Scenario: Driving 20 mA indicator LEDs from 3.3 V GPIO pins in IoT edge nodes.

IC Role / Device Role / Timing Role: Saturated switch controlling LED anode connection to V_CC with base driven by microcontroller output.

Use Value: Achieves <0.3 V dropout at 20 mA, reducing power loss by 40% vs. higher-V_CE(sat) transistors and extending battery life.

Logic-Level Translator

Current Mirror Reference

Use Scenario: Converting 1.8 V CMOS logic outputs to 5 V levels for legacy peripherals in mixed-voltage systems.

IC Role / Device Role / Timing Role: NPN switch in emitter-follower or common-base configuration to shift voltage thresholds without inversion.

Use Value: Supports <35 ns propagation delay and <50 ns fall time, preserving signal integrity for 10 MHz digital buses.

Use Scenario: Building matched current sources in precision analog sensor conditioning circuits (e.g., RTD bridges).

IC Role / Device Role / Timing Role: Paired MMBT3904WT1 devices in monolithic layout to replicate reference current with <5% mismatch over temperature.

Use Value: Leverages tight h_FE distribution and identical thermal coefficients to maintain <0.5% current tracking from −40°C 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
BC847BW	Same SOT-323 package; V_CEO = 45 V, h_FE = 110–220 @ 10 mA, f_T = 100 MHz - lower bandwidth but tighter h_FE binning.	Better suited for precision DC amplification where gain consistency matters more than RF response.	Select BC847BW when h_FE tolerance <±15% is required and f_T > 200 MHz is unnecessary.
PN2222A-RTK/P	SOT-23 package; V_CEO = 40 V, I_C = 600 mA, P_D = 350 mW - higher power handling but larger footprint and slower switching (t_f ≈ 250 ns).	Preferred for driving heavier loads (e.g., relays, solenoids) where 200 mA limit of MMBT3904WT1 is insufficient.	Choose PN2222A-RTK/P only if load current exceeds 200 mA or thermal budget allows larger package.

Compared with BC847BW and PN2222A-RTK/P, the MMBT3904WT1 uniquely balances RF capability (300 MHz f_T), ultra-compact size (SOT-323), and robust switching speed (t_f ≤ 50 ns), making it optimal for space-constrained, medium-frequency signal-path designs where both gain stability and bandwidth matter.

Availability

MMBT3904WT1 is available at Aetrix Electronics and suitable for portable audio, sensor interface, and logic-level translation applications requiring stable component supply, consistent parametric performance, and long-term manufacturing continuity.

Supply support for MMBT3904WT1 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, and cloud infrastructure markets.

The MMBT3904WT1 belongs to onsemi's general-purpose transistor family designed for cost-sensitive, high-volume applications demanding reliability, small form factor, and broad operating temperature support in consumer and industrial electronics.

FAQ

What is the maximum continuous collector current for MMBT3904WT1?

The MMBT3904WT1 has a maximum continuous collector current (I_C) rating of 200 mA at T_A = 25°C. This value decreases with rising ambient temperature per the derating curve in the datasheet; at 100°C, usable I_C drops to approximately 120 mA. The MMBT3904WT1 must be operated within this limit to avoid thermal runaway or permanent degradation.

Is MMBT3904WT1 RoHS-compliant and lead-free?

Yes, the MMBT3904WT1 is Pb-free, halogen-free, and fully RoHS-compliant, as confirmed in the official onsemi datasheet (Publication Order Number: MMBT3904WT1/D, Rev. 10). The "G" suffix in part variants like MMBT3904WT1G explicitly denotes the lead-free packaging, and the device meets JEDEC J-STD-609 Category 1 marking requirements.

What is the typical DC current gain (h_FE) of MMBT3904WT1 at 10 mA collector current?

The MMBT3904WT1 exhibits a typical DC current gain (h_FE) of 100–300 at I_C = 10 mA, V_CE = 1.0 V, and T_A = 25°C. This wide range reflects standard production binning; design margins should accommodate the minimum value (100) for reliable saturation in switching applications or use h_FE = 200 as a nominal center point for linear amplifier biasing.

Can MMBT3904WT1 be used in RF amplifier stages?

Yes, the MMBT3904WT1 supports RF amplification up to 300 MHz (f_T), making it suitable for VHF-band pre-amplifiers, oscillator buffers, and low-noise receiver front-ends. Its low C_obo (4.0 pF) and C_ibo (8.0 pF), combined with NF = 5.0 dB at 1 kHz, enable clean signal amplification in portable radios and wireless sensor transceivers when properly impedance-matched.

What is the thermal resistance (R_JA) of MMBT3904WT1 on a standard FR4 PCB?

The MMBT3904WT1 has a thermal resistance (R_JA) of 833°C/W when mounted on a standard FR4 printed circuit board using the minimum recommended footprint per the onsemi datasheet. This value assumes no additional copper pour or thermal vias; adding 1-in² copper area can reduce R_JA to ~300°C/W, significantly improving power handling capability for the MMBT3904WT1.

MMBT3904WT1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: *

Package/Case:: -

Packaging:: Cut Tape (CT)

Product Status:: Obsolete

Transistor Type:: -

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

Voltage - Collector Emitter Breakdown (Max):: -

Vce Saturation (Max) @ Ib, Ic:: -

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: -

Power - Max:: -

Frequency - Transition:: -

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: -

Supplier Device Package:: -

MMBT3904WT1 FAQ

1.How can I place an order for MMBT3904WT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBT3904WT1 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 MMBT3904WT1 reliable?

The price and inventory of MMBT3904WT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBT3904WT1 is usually 5 days.

3.What payment methods are accepted for MMBT3904WT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBT3904WT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBT3904WT1?

MMBT3904WT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBT3904WT1 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 MMBT3904WT1?

For technical support, including MMBT3904WT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBT3904WT1 requirements.

6.How does Aetrix verify that MMBT3904WT1 is sourced from the original manufacturer or authorized distributors?

All MMBT3904WT1 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 MMBT3904WT1 meets industry standards.

7.What is the process for return or replacement of MMBT3904WT1?

All MMBT3904WT1 units undergo pre-shipment inspection (PSI). If there is an issue with MMBT3904WT1, 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 MMBT3904WT1 part is unused and in its original packaging.

Return procedure for MMBT3904WT1:

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…