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

Diodes Incorporated MMST4124-7

Name: MMST4124-7
Brand: Diodes Incorporated
SKU: MMST4124-7
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMST4124-7

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: -

Datasheet:: MMST4124-7.pdf

Description:: TRANS NPN 25V 0.2A SC70-3

Quantity:: RFQ Add To RFQ list

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Inventory:21

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Product details

Overview

MMST4124-7 from Diodes Incorporated is an NPN small-signal transistor in SOT323 package, rated for 25V V_CEO, 200mA I_C, and 200mW power dissipation. It features epitaxial planar die construction, AEC-Q101 qualification for automotive reliability, and operates across −55°C to +150°C. It serves as a general-purpose switching and amplification device in compact DC-DC feedback paths and sensor interface stages.

For engineers reviewing the MMST4124-7 datasheet, MMST4124-7 pinout, MMST4124-7 application, or MMST4124-7 equivalent, key selection criteria include its 300MHz f_T, low 0.30V V_CE(SAT) at 50mA/5mA drive, 120–600 h_FE range, ESD robustness (4kV HBM), and SOT323 footprint compatibility with space-constrained PCB layouts.

Technical Context

This NPN bipolar junction transistor uses epitaxial planar die construction to ensure stable gain and low leakage across temperature extremes. Its 300MHz current-gain bandwidth product supports high-speed switching up to ~100MHz in digital logic interfaces and pulse-width modulation circuits.

The device delivers 0.30V collector-emitter saturation voltage at 50mA collector current with 5mA base drive, enabling efficient low-voltage switching in 3.3V and 5V rail applications. Its 4pF output capacitance and 8pF input capacitance minimize signal distortion in RF-coupled preamplifier stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25V - Maximum safe collector-emitter voltage before breakdown; enables use in 24V industrial control nodes.
I_C	200mA - Continuous collector current rating; supports medium-current load switching (e.g., LED drivers, relay coils).
f_T	300MHz - Current-gain bandwidth product; suitable for RF preamp and fast digital signal conditioning up to 100MHz.
V_CE(SAT)	0.30V @ 50mA/5mA - Low saturation voltage reduces conduction loss and self-heating in high-duty-cycle switching.
h_FE	120–600 @ 2mA–50mA - Wide DC current gain range ensures consistent biasing across production lots and temperature.
ESD HBM	4,000V - Human Body Model rating confirms robustness during manual handling and board-level assembly.
R_θJA	625°C/W - Thermal resistance defines junction-to-ambient rise per watt; requires minimal copper area for thermal management.

Pinout & Package

SOT323 ultra-small surface-mount package: 3-pin, plastic-molded, lead-free, halogen-free, moisture sensitivity level 1. Dimensions: 2.15mm × 2.10mm × 0.95mm (L × W × H), weight ≈ 0.006g.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitting terminal for majority carriers	Connected to ground or low-side reference; determines current sink capability and bias stability.
2 (Base)	Control electrode for carrier injection	Receives drive current to modulate collector current; requires series resistor to limit I_B and prevent saturation overshoot.
3 (Collector)	Current collection node	Connected to load or supply rail; handles full switched current and must route heat via copper pad per JEDEC layout guidelines.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD stress - supports under-hood and ADAS sensor modules.
Ultra-small SOT323 footprint	2.15mm × 2.10mm outline enables placement in dense routing zones, such as portable medical sensor PCBs and wearables.
Low V_CE(SAT) at high I_C	0.30V at 50mA/5mA drive minimizes power loss and thermal rise in battery-powered 3.3V logic-level switching applications.
High f_T with low C_obo	300MHz gain-bandwidth with only 4pF output capacitance enables clean signal amplification in 10–50MHz analog front-ends.
Green, RoHS-compliant construction	Halogen- and antimony-free molding compound (<900ppm Br/Cl, <1000ppm Sb) meets IPC-1752A material declaration requirements.

Applications

Automotive Sensor Interface

Portable Medical Instrumentation

Use Scenario: Amplifying low-level thermistor or Hall-effect sensor outputs in vehicle cabin temperature or position sensing modules.

IC Role / Device Role / Timing Role: NPN amplifier stage providing 10–100× voltage gain with minimal offset drift over −40°C to +125°C.

Use Value: AEC-Q101 qualification and 150°C max operating temperature ensure long-term stability in unregulated ambient environments.

Use Scenario: Driving piezoelectric transducers or low-power OLED displays in handheld diagnostic devices.

IC Role / Device Role / Timing Role: Medium-current switch controlling 50–150mA loads from microcontroller GPIO pins.

Use Value: 0.30V V_CE(SAT) preserves battery life by limiting conduction loss in intermittent-use clinical equipment.

Industrial PLC I/O Expansion

Consumer Audio Signal Conditioning

Use Scenario: Level-shifting and buffering digital signals between 3.3V MCU and 24V fieldbus peripherals in modular controllers.

IC Role / Device Role / Timing Role: Digital switch translating logic states with fast turn-on/turn-off times enabled by 300MHz f_T.

Use Value: 25V V_CEO withstands transient surges on industrial backplanes without clamping diodes.

Use Scenario: Biasing JFET-input op-amp stages or forming active filters in Bluetooth speaker audio paths.

IC Role / Device Role / Timing Role: Small-signal amplifier providing stable h_FE across 2mA–20mA bias currents for low-noise gain blocks.

Use Value: 8pF C_ibo and 4pF C_obo reduce high-frequency roll-off and phase shift in 20kHz–100kHz bandpass networks.

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
MMST3904-7	Higher h_FE (min 100 @ 10mA), lower V_CE(SAT) (0.2V), same SOT323 package and pinout.	Preferred where tighter gain tolerance and lower saturation loss are required in precision analog switches.	Select MMST3904-7 when replacing MMST4124-7 in new designs requiring improved consistency at low I_C.
BC846B-7-F	Same V_CEO (65V), higher I_C (100mA continuous), different h_FE binning (200–450), SOT23 package.	Requires PCB redesign due to SOT23 footprint; suited for higher-voltage, lower-current bias networks.	Choose BC846B-7-F only if board revision allows SOT23 pad changes and system demands >25V blocking capability.

Compared with MMST4124-7, MMST3904-7 offers superior gain consistency and lower saturation voltage in identical packaging, while BC846B-7-F trades SOT323 compatibility for higher voltage rating and different thermal profile - making MMST3904-7 the preferred drop-in upgrade path.

Availability

MMST4124-7 is available at Aetrix Electronics and suitable for automotive sensor interfaces, portable medical instrumentation, and industrial PLC I/O expansion requiring stable component supply despite its obsolete status.

Supply support for MMST4124-7 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 centers across Asia and manufacturing in China, Taiwan, and Malaysia.

The MMST4124-7 belongs to Diodes' AEC-Q101-qualified small-signal transistor family, engineered for reliability in automotive, industrial, and portable electronics where miniaturization and thermal resilience are critical.

FAQ

Is MMST4124-7 still in production?

No. Diodes Incorporated has discontinued MMST4124-7 and marked it obsolete as of June 2021. Aetrix Electronics maintains limited legacy stock for continuity support, but new designs should migrate to MMST3904-7, which shares identical SOT323 packaging and improved electrical specs.

What is the correct pinout orientation for MMST4124-7 in SOT323?

With the marking side up and the tab facing away, pin 1 (Emitter) is leftmost, pin 2 (Base) is center, and pin 3 (Collector) is rightmost. This matches the top-view diagram in DS30163 Rev. 11–4, page 2, and is consistent with JEDEC standard SOT323 pin assignment.

Can MMST4124-7 be used in place of BC847 in SOT23?

No. MMST4124-7 uses SOT323 (2.15mm × 2.10mm), while BC847 uses SOT23 (3.0mm × 1.4mm); their footprints are incompatible. Electrical differences - including lower V_CEO (25V vs. 45V) and different h_FE bins - further preclude direct substitution without circuit validation.

Does MMST4124-7 require derating above 25°C ambient?

Yes. Its 200mW maximum power dissipation linearly derates above 25°C at 0.32mW/°C (based on R_θJA = 625°C/W). At 70°C ambient, usable power drops to 56mW. Layout must follow Diodes' recommended SOT323 pad dimensions to maintain thermal performance.

MMST4124-7 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: *

Package/Case:: -

Packaging:: Cut Tape (CT)

Product Status:: Active

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:: -

MMST4124-7 FAQ

1.How can I place an order for MMST4124-7 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMST4124-7 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 MMST4124-7 reliable?

The price and inventory of MMST4124-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMST4124-7 is usually 5 days.

3.What payment methods are accepted for MMST4124-7?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMST4124-7 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMST4124-7?

MMST4124-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMST4124-7 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 MMST4124-7?

For technical support, including MMST4124-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMST4124-7 requirements.

6.How does Aetrix verify that MMST4124-7 is sourced from the original manufacturer or authorized distributors?

All MMST4124-7 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 MMST4124-7 meets industry standards.

7.What is the process for return or replacement of MMST4124-7?

All MMST4124-7 units undergo pre-shipment inspection (PSI). If there is an issue with MMST4124-7, 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 MMST4124-7 part is unused and in its original packaging.

Return procedure for MMST4124-7:

1.Submit a request within 90 days.

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

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