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

Diodes Incorporated MMBT3904-7

Name: MMBT3904-7
Brand: Diodes Incorporated
SKU: MMBT3904-7
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBT3904-7

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: MMBT3904-7.pdf

Description:: TRANS NPN 40V 0.2A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MMBT3904-7 from Diodes Incorporated is an NPN small-signal surface-mount transistor in SOT-23 package, rated for 40 V V_CEO, 200 mA I_C, and 350 mW P_D, used in medium-power amplification and switching circuits such as level-shifting stages in microcontroller I/O interfaces and LED driver bias networks.

For engineers reviewing the MMBT3904-7 datasheet, MMBT3904-7 pinout, MMBT3904-7 application, or MMBT3904-7 equivalent, key selection criteria include DC current gain (h_FE = 40–300), V_CE(SAT) ≤ 0.30 V at I_C = 50 mA, f_T = 300 MHz, thermal resistance R_JA = 357 K/W, and complementary pairing with MMBT3906.

Technical Context

This epitaxial planar NPN transistor operates in linear amplification and saturated switching modes, with verified h_FE spanning 40–300 across I_C = 100 µA to 100 mA and V_CE = 1.0 V. Its f_T of 300 MHz supports RF preamplifier and high-speed digital interface applications up to ~100 MHz.

Switching performance is characterized by t_d = 35 ns, t_r = 35 ns, t_s = 200 ns, and t_f = 50 ns under V_CC = 3.0 V, enabling use in 1–5 MHz pulse-width modulation drivers and logic-level translators.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum collector-emitter voltage before breakdown; sets safe operating range in 3.3 V/5 V logic-switched loads.
I_C (cont.)	200 mA - Continuous collector current limit; supports driving small relays, LEDs, or gate capacitance of low-side MOSFETs.
P_D	350 mW - Power dissipation at T_A = 25 °C; requires derating above 25 °C per R_JA = 357 K/W.
h_FE	40–300 - DC current gain range across I_C = 100 µA–100 mA; enables stable bias design in common-emitter amplifier stages.
f_T	300 MHz - Transition frequency; validates suitability for RF amplification up to VHF band and fast digital signal conditioning.
V_CE(SAT)	0.20–0.30 V - Saturation voltage at I_C/I_B = 10/1 mA and 50/5 mA; ensures low conduction loss in switching applications.
NF	5.0 dB - Noise figure at V_CE = 5 V, I_C = 100 µA, R_S = 1 kΩ; specifies low-noise capability for audio preamp front-ends.

Pinout & Package

Package: SOT-23 - Surface-mount plastic package with gull-wing leads, 0.008 g weight, JEDEC-compliant footprint (A: 0.37–0.51 mm, B: 1.19–1.40 mm, C: 2.10–2.50 mm).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or low-impedance return path; defines reference for V_BE and I_E flow.
2 (Base)	Control input	Receives bias current to modulate collector current; requires series resistor for current-limited drive from MCU GPIO.
3 (Collector)	Current source terminal	Delivers amplified/saturated output current to load; routed to V_CC via pull-up or connected to switched load.

Key Features

Feature	Design Value
Complementary PNP pair	MMBT3906 available - Enables push-pull output stages and differential amplifiers without cross-manufacturer sourcing.
High f_T	300 MHz - Supports broadband amplification and fast edge-rate signal buffering in communication interfaces.
Low V_CE(SAT)	≤ 0.30 V at I_C = 50 mA - Reduces power loss and self-heating in high-duty-cycle switching applications.
Wide h_FE range	40–300 - Accommodates production spread while maintaining functional margin in bias-critical analog stages.
Robust ESD rating	HBM > 8 kV - Meets IEC 61000-4-2 Level 4; reduces need for external protection in board-level ESD-prone environments.

Applications

LED Driver Stage

Microcontroller I/O Interface

Use Scenario: Driving 20 mA indicator LEDs from 3.3 V GPIO pins with current-limiting resistor.

IC Role / Device Role / Timing Role: NPN switch operating in saturation mode, controlled by digital output.

Use Value: V_CE(SAT) ≤ 0.30 V minimizes voltage drop, preserving LED forward voltage margin and ensuring consistent brightness.

Use Scenario: Level-shifting between 5 V sensor outputs and 3.3 V MCU inputs using open-collector configuration.

IC Role / Device Role / Timing Role: Active-low inverter with pull-up resistor, providing logic-compatible voltage translation.

Use Value: h_FE ≥ 40 ensures reliable turn-on with <100 µA base drive, reducing loading on upstream sensors.

Audio Pre-amplifier

Small Relay Driver

Use Scenario: First-stage gain block in electret microphone amplifier with 1 kΩ collector load.

IC Role / Device Role / Timing Role: Common-emitter amplifier biased at I_C ≈ 1 mA for optimal NF and linearity.

Use Value: NF = 5.0 dB and h_FE = 100–400 (h_fe) enable SNR > 60 dB in battery-powered voice recorders.

Use Scenario: Driving 12 V, 40 mA coil of SPST relay from 3.3 V MCU via base resistor network.

IC Role / Device Role / Timing Role: Medium-current saturated switch with forced β = 10 to ensure deep saturation.

Use Value: I_C = 200 mA rating and t_f = 50 ns support clean relay deactivation without contact arcing or bounce.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC847B,115 (Nexperia)	V_CEO = 45 V, h_FE = 200–450 at I_C = 2 mA, R_JA = 375 K/W	Higher h_FE improves low-current bias stability but slightly lower power rating	Preferred for precision bias networks where gain consistency at µA-level I_C is critical
PN2222A (ON Semiconductor)	TO-92 package, V_CEO = 40 V, I_C = 800 mA, P_D = 1 W, f_T = 300 MHz	Through-hole, higher current/power, same f_T; not SMT-compatible	Used when board space allows through-hole mounting and higher surge current handling is required

Compared with BC847B and PN2222A, MMBT3904-7 offers optimal balance of SOT-23 footprint, 200 mA capability, and 300 MHz f_T, making it preferred for space-constrained, medium-speed digital and analog designs requiring surface-mount assembly.

Availability

MMBT3904-7 is available at Aetrix Electronics and suitable for LED driver stages, microcontroller I/O interfaces, audio pre-amplifiers, and small relay drivers requiring stable component supply across industrial control, consumer electronics, and IoT endpoint designs.

Supply support for MMBT3904-7 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability, cost-optimized components for power management, signal integrity, and interface applications.

The MMBT3904-7 belongs to Diodes' small-signal transistor product line, engineered for general-purpose amplification and switching in compact, high-volume PCB assemblies where thermal efficiency and SMT compatibility are essential.

FAQ

What is the maximum junction temperature for MMBT3904-7?

The absolute maximum junction temperature is +150 °C, with storage temperature also rated from –55 °C to +150 °C. Derating begins at T_A > 25 °C using R_JA = 357 K/W; at T_A = 70 °C, maximum allowable P_D drops to approximately 200 mW.

Is MMBT3904-7 RoHS compliant and halogen-free?

Yes, MMBT3904-7 meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. The SOT-23 package uses lead-free matte tin plating and complies with JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) for unlimited floor life at ≤30 °C/85% RH.

How does MMBT3904-7 differ from MMBT3904 (no suffix)?

The "-7" suffix denotes tape-and-reel packaging per EIA-481 standard, with 3,000 units per reel and 8 mm carrier tape width. Electrically and thermally identical to MMBT3904, the suffix indicates packaging format only-no parametric or reliability differences exist between versions.

Can MMBT3904-7 replace BC547 in existing designs?

Yes, with verification of layout and bias conditions: both are NPN transistors with similar V_CEO (45 V for BC547), h_FE, and f_T. However, MMBT3904-7's SOT-23 footprint requires pad redesign, and its lower P_D (350 mW vs. 500 mW for BC547 in TO-92) demands thermal validation in high-duty-cycle operation.

MMBT3904-7 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 40 V

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

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 10mA, 1V

Power - Max:: 300 mW

Frequency - Transition:: 300MHz

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

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

MMBT3904-7 FAQ

1.How can I place an order for MMBT3904-7 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBT3904-7 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 MMBT3904-7 reliable?

The price and inventory of MMBT3904-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBT3904-7 is usually 5 days.

3.What payment methods are accepted for MMBT3904-7?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBT3904-7 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBT3904-7?

MMBT3904-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBT3904-7 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 MMBT3904-7?

For technical support, including MMBT3904-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBT3904-7 requirements.

6.How does Aetrix verify that MMBT3904-7 is sourced from the original manufacturer or authorized distributors?

All MMBT3904-7 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 MMBT3904-7 meets industry standards.

7.What is the process for return or replacement of MMBT3904-7?

All MMBT3904-7 units undergo pre-shipment inspection (PSI). If there is an issue with MMBT3904-7, 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 MMBT3904-7 part is unused and in its original packaging.

Return procedure for MMBT3904-7:

1.Submit a request within 90 days.

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

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