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

Diodes Incorporated MMST3904-7

Name: MMST3904-7
Brand: Diodes Incorporated
SKU: MMST3904-7
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMST3904-7

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: SC-70, SOT-323

Datasheet:: MMST3904-7.pdf

Description:: TRANS NPN 40V 0.2A SOT-323

Quantity:: RFQ Add To RFQ list

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Inventory:9,606

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Product details

Overview

MMST3904-7 from Diodes Incorporated is an NPN small-signal surface-mount transistor in SOT-323 package, rated for 40 V V_CEO, 200 mA I_C, and 200 mW P_D, with h_FE = 100–300 at I_C = 10 mA, used in general-purpose switching and amplification circuits on space-constrained PCBs.

For engineers reviewing the MMST3904-7 datasheet, MMST3904-7 pinout, MMST3904-7 application, or MMST3904-7 equivalent, key selection criteria include V_CEO/I_C derating at elevated ambient temperature, SOT-323 thermal resistance (625 °C/W), and h_FE variation across collector current range.

Technical Context

This epitaxial planar NPN transistor operates in active, saturation, and cutoff regions with verified DC gain (h_FE) spanning 40–300 across I_C = 100 µA to 100 mA and V_CE = 1.0 V. Its f_T = 300 MHz supports RF amplifier stages up to UHF.

Switching performance is characterized by t_d = 35 ns and t_r = 35 ns under V_CC = 3.0 V, I_C = 10 mA, and I_B1 = 1.0 mA conditions; V_CE(SAT) ≤ 0.30 V at I_C = 50 mA / I_B = 5.0 mA confirms low-loss switching capability.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum safe collector-emitter voltage before breakdown in common-emitter configuration
I_C (max)	200 mA - Continuous collector current limit at T_A = 25 °C, derated above 25 °C per R_JA = 625 °C/W
h_FE	100–300 - DC current gain at I_C = 10 mA, V_CE = 1.0 V, defining base drive sizing for linear/switching use
f_T	300 MHz - Transition frequency where \|h_fe\| = 1, indicating usable bandwidth for RF amplification
V_CE(SAT)	0.25–0.30 V - Saturation voltage at I_C = 10–50 mA, directly impacting power loss in switch-mode operation
R_JA	625 °C/W - Junction-to-ambient thermal resistance on FR-4 PCB per AP02001 layout, governing max power at given T_A

Pinout & Package

SOT-323 (SC-70) ultra-small surface-mount plastic package with gull-wing leads; moisture sensitivity level 1 per J-STD-020A; lead-free matte tin finish available (-F suffix).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emission terminal for majority carriers	Reference node for bias network; connects to ground or low-impedance return path in common-emitter topology
2 (Base)	Control electrode for carrier injection	Receives current-limited drive signal; requires series resistor to limit I_B based on h_FE and target I_C
3 (Collector)	Current collection terminal	Connects to load or supply rail; voltage swing limited by V_CEO = 40 V and thermal dissipation constraints

Key Features

Feature	Design Value
Ultra-small footprint	SOT-323 package (2.2 × 1.35 × 0.9 mm) enables high-density routing in portable and IoT PCB layouts
High f_T	300 MHz transition frequency supports stable amplification in 2.4 GHz ISM-band receiver front-ends
Low V_CE(SAT)	≤0.30 V at I_C/I_B = 10 ensures <15 mW conduction loss in 5 V logic-level switching applications
Wide h_FE range	40–300 across I_C = 100 µA–100 mA allows single part to serve both micro-power biasing and medium-drive switching

Applications

LED Driver Circuit

Signal Amplifier Stage

Use Scenario: Driving discrete indicator LEDs from MCU GPIO pins with 3.3 V or 5 V supply rails.

IC Role / Device Role / Timing Role: NPN switch controlling LED anode/cathode current path with digital base drive.

Use Value: V_CE(SAT) ≤ 0.30 V minimizes voltage drop across transistor, preserving forward voltage margin for red/green/blue LEDs.

Use Scenario: Low-noise preamplification of sensor outputs (e.g., thermistor, photodiode) before ADC sampling.

IC Role / Device Role / Timing Role: Common-emitter small-signal amplifier with emitter degeneration for stable gain.

Use Value: NF = 5.0 dB at I_C = 100 µA enables sub-10 µV input-referred noise in 1 kHz bandwidth designs.

Logic Level Translator

RF Detector Bias Stage

Use Scenario: Translating 1.8 V logic signals to 5 V domains in mixed-voltage microcontroller systems.

IC Role / Device Role / Timing Role: Saturated switch converting low-voltage input to higher-voltage output via pull-up resistor.

Use Value: h_FE ≥ 100 at I_C = 1 mA ensures reliable saturation with minimal base drive current from low-power I/O pins.

Use Scenario: Providing stable DC bias current to Schottky diode detectors in 868 MHz wireless sensor transmitters.

IC Role / Device Role / Timing Role: Constant-current source using emitter resistor feedback and temperature-compensated base bias.

Use Value: V_(BR)EBO = 5.0 V and T_j range of –55 to +150 °C support robust operation near RF power stages.

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
BC847BW	Same SOT-323 package; h_FE = 110–220 at I_C = 10 mA; V_CEO = 45 V; f_T = 100 MHz	Lower f_T limits RF use; higher V_CEO suits 5–12 V industrial controls	Select when wider V_CEO margin is needed and RF bandwidth is not required
MMBT3904LT1G	SOT-23 package; h_FE = 100–300; V_CEO = 40 V; f_T = 300 MHz; R_JA = 300 °C/W	Larger footprint but superior thermal performance enables 300+ mW continuous operation	Select when board space permits and higher power dissipation is required

Compared with BC847BW and MMBT3904LT1G, MMST3904-7 uniquely balances ultra-compact SOT-323 size, 300 MHz f_T, and 625 °C/W thermal resistance-making it optimal for miniaturized RF and battery-powered signal chains where PCB area is constrained but bandwidth matters.

Availability

MMST3904-7 is available at Aetrix Electronics and suitable for LED driver circuits, sensor signal amplifiers, logic level translators, and RF detector bias stages requiring stable component supply and consistent parametric performance across production lots.

Supply support for MMST3904-7 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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

The MMST3904-7 belongs to Diodes' small-signal transistor product line, engineered for high-volume consumer, computing, and communications applications where miniature packaging, parametric consistency, and JEDEC-compliant reliability are essential.

FAQ

What is the maximum junction temperature for MMST3904-7?

The absolute maximum junction temperature is +150 °C, matching its storage temperature rating. Operation at this limit requires strict adherence to derated power dissipation per Figure 1 in the datasheet-e.g., P_D drops to ~100 mW at T_A = 75 °C using R_JA = 625 °C/W.

Is MMST3904-7 RoHS compliant and halogen-free?

Yes-MMST3904-7 is RoHS compliant and halogen-free per Diodes Incorporated's material declarations. The lead-free version (marked -F suffix) uses matte tin plating and meets IPC/JEDEC J-STD-020A moisture sensitivity level 1 requirements.

How does h_FE vary with temperature for MMST3904-7?

h_FE increases with temperature: Figure 3 shows typical values rising from ~100 at –25 °C to ~200 at +125 °C at I_C = 10 mA and V_CE = 1.0 V. Designers must account for this in bias-stable amplifier configurations.

Can MMST3904-7 replace BC846B in existing SOT-323 designs?

Yes-MMST3904-7 shares identical SOT-323 pinout and comparable V_CEO/I_C ratings, but offers higher f_T (300 MHz vs. 100 MHz) and broader h_FE range. Verify base resistor values due to h_FE distribution differences, especially in saturation-critical switching.

MMST3904-7 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

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

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):: -

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

Power - Max:: 200 mW

Frequency - Transition:: 300MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-323

MMST3904-7 FAQ

1.How can I place an order for MMST3904-7 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMST3904-7 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 MMST3904-7 reliable?

The price and inventory of MMST3904-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMST3904-7 is usually 5 days.

3.What payment methods are accepted for MMST3904-7?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMST3904-7 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMST3904-7?

MMST3904-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMST3904-7 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 MMST3904-7?

For technical support, including MMST3904-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMST3904-7 requirements.

6.How does Aetrix verify that MMST3904-7 is sourced from the original manufacturer or authorized distributors?

All MMST3904-7 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 MMST3904-7 meets industry standards.

7.What is the process for return or replacement of MMST3904-7?

All MMST3904-7 units undergo pre-shipment inspection (PSI). If there is an issue with MMST3904-7, 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 MMST3904-7 part is unused and in its original packaging.

Return procedure for MMST3904-7:

1.Submit a request within 90 days.

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

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