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

onsemi FMMT449

Name: FMMT449
Brand: onsemi
SKU: FMMT449
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FMMT449

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: FMMT449.pdf

Description:: TRANS NPN 30V 1A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

FMMT449 from ON Semiconductor is an NPN low-saturation transistor in SuperSOT™-3 package, rated for 2 A continuous collector current, 30 V V_CEO, and 500 mV V_CE(sat) at I_C = 1 A / I_B = 100 mA. It delivers high DC current gain (h_FE ≥ 70 at I_C = 1 A) and 150 MHz f_T, optimized for high-efficiency switching in compact DC-DC converters and load-switching circuits.

For engineers reviewing the FMMT449 datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CE(sat) at 1–2 A, thermal resistance (R_θJA = 250°C/W on FR-4), SuperSOT™-3 footprint compatibility, and guaranteed h_FE minimum across operating temperature range.

Technical Context

This device uses Fairchild's Process NB to achieve low saturation voltage while maintaining robust switching speed. Its 150 MHz transition frequency and 15 pF C_obo support medium-frequency switching up to several hundred kHz without excessive switching losses.

The SuperSOT™-3 package enables high power density with a 0.02 in² copper pad on FR-4 PCB, delivering 500 mW total dissipation at 25°C and derating linearly above that temperature. Junction temperature is rated from –55°C to +150°C, supporting industrial ambient operation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CE(sat)	500 mV max at I_C = 1 A, I_B = 100 mA - enables <1 W conduction loss in 1 A load-switching applications
h_FE	70–100 min at I_C = 1 A, V_CE = 2 V - ensures reliable base drive margin for discrete gate control
f_T	150 MHz at I_C = 50 mA, V_CE = 10 V - supports fast turn-on/turn-off in PWM-driven power stages
R_θJA	250°C/W on FR-4 (4.5″ × 5″, 0.02 in² 2 oz Cu) - defines thermal headroom for 1–2 A continuous operation
V_CEO	30 V - sets maximum blocking voltage in low-voltage DC-DC and battery-powered systems
I_C (cont)	2 A - specifies absolute maximum steady-state collector current under validated thermal conditions

Pinout & Package

Package: SuperSOT™-3 - surface-mount, 3-pin, thermally enhanced plastic package with exposed emitter pad; footprint compatible with industry-standard SOT-23 but with improved thermal performance.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitting terminal for majority carriers	Connected to ground or low-side return path; large copper pad improves heat transfer and current handling
2 (Base)	Control electrode for carrier injection	Receives current-limited drive signal; requires ~100 mA for full saturation at 1 A collector load
3 (Collector)	Current collection node	Connected to switched load or power rail; handles up to 2 A continuous with proper PCB thermal design

Key Features

Feature	Design Value
Low V_CE(sat)	500 mV max at 1 A - reduces conduction loss by >40% vs. standard general-purpose transistors
High h_FE	Min 70 at 1 A - lowers required base drive current and simplifies driver circuitry
Thermally optimized package	R_θJA = 250°C/W - enables higher current density than SOT-23 in space-constrained layouts
Wide operating temperature	–55°C to +150°C junction range - supports deployment in automotive under-hood and industrial motor-control environments

Applications

DC-DC Converter Switch	Load Switch for Industrial PLC
Use Scenario: Used as main switching element in non-synchronous buck converter operating at 200–500 kHz with 12 V input and 5 V/1.5 A output. IC Role / Device Role / Timing Role: NPN power switch controlled by external PWM controller; conducts during on-time, blocks during off-time. Use Value: Low 500 mV V_CE(sat) minimizes I²R loss at 1.5 A, improving efficiency by ~2.5% over standard transistors.	Use Scenario: Controls 24 V DC solenoid loads (1.2 A nominal) in programmable logic controller output modules. IC Role / Device Role / Timing Role: Discrete high-current load switch driven by microcontroller GPIO via base resistor network. Use Value: Guaranteed h_FE ≥ 70 ensures full saturation with ≤10 mA base current, reducing MCU drive burden and PCB component count.
LED Driver for Automotive Interior	Motor Commutation in Small BLDC Fan
Use Scenario: Drives 3-series white LED string (9 V forward, 350 mA) in automotive cabin lighting with PWM dimming. IC Role / Device Role / Timing Role: Low-side constant-current switch modulated at 1–5 kHz; handles peak pulses up to 500 mA. Use Value: 150 MHz f_T and low C_obo ensure clean PWM edges and minimal switching distortion at dimming frequencies.	Use Scenario: Implements low-side commutation in 12 V, 2-pole brushless DC fan with hall-effect sensor feedback. IC Role / Device Role / Timing Role: One of three synchronized NPN switches in half-bridge configuration; switches at ≤20 kHz. Use Value: 2 A I_C rating and 30 V V_CEO provide safe margin against inductive kickback and startup surges.

DC-DC Converter Switch

Load Switch for Industrial PLC

Use Scenario: Used as main switching element in non-synchronous buck converter operating at 200–500 kHz with 12 V input and 5 V/1.5 A output.

IC Role / Device Role / Timing Role: NPN power switch controlled by external PWM controller; conducts during on-time, blocks during off-time.

Use Value: Low 500 mV V_CE(sat) minimizes I²R loss at 1.5 A, improving efficiency by ~2.5% over standard transistors.

Use Scenario: Controls 24 V DC solenoid loads (1.2 A nominal) in programmable logic controller output modules.

IC Role / Device Role / Timing Role: Discrete high-current load switch driven by microcontroller GPIO via base resistor network.

Use Value: Guaranteed h_FE ≥ 70 ensures full saturation with ≤10 mA base current, reducing MCU drive burden and PCB component count.

LED Driver for Automotive Interior

Motor Commutation in Small BLDC Fan

Use Scenario: Drives 3-series white LED string (9 V forward, 350 mA) in automotive cabin lighting with PWM dimming.

IC Role / Device Role / Timing Role: Low-side constant-current switch modulated at 1–5 kHz; handles peak pulses up to 500 mA.

Use Value: 150 MHz f_T and low C_obo ensure clean PWM edges and minimal switching distortion at dimming frequencies.

Use Scenario: Implements low-side commutation in 12 V, 2-pole brushless DC fan with hall-effect sensor feedback.

IC Role / Device Role / Timing Role: One of three synchronized NPN switches in half-bridge configuration; switches at ≤20 kHz.

Use Value: 2 A I_C rating and 30 V V_CEO provide safe margin against inductive kickback and startup surges.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN low-saturation transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZXTN25050DFH	Higher V_CEO (50 V), lower R_θJA (150°C/W), same SuperSOT™-3 package	Better suited for 24–48 V systems; superior thermal performance allows higher continuous current	Select when operating voltage exceeds 30 V or board-level thermal management is limited
MMBT4401	Lower I_C rating (600 mA), higher V_CE(sat) (750 mV), SOT-23 package	Not suitable for >0.6 A loads; lacks thermal capability for sustained 1 A operation	Acceptable only for signal-level or low-power switching where current and thermal demands are significantly lower

Compared with ZXTN25050DFH, FMMT449 offers lower cost and adequate voltage margin for 12–24 V systems, while MMBT4401 serves only light-duty roles-neither is pin-compatible, but both require layout adaptation for replacement.

Availability

FMMT449 is available at Aetrix Electronics and suitable for DC-DC converters, industrial load switching, automotive LED drivers, and small BLDC motor commutation requiring stable component supply and long-term industrial availability.

Supply support for FMMT449 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

FMMT449 belongs to ON Semiconductor's legacy Fairchild low-saturation transistor product line, engineered specifically for high-current, low-loss discrete switching in space- and thermally constrained power management applications.

FAQ

What is the maximum continuous collector current rating for FMMT449?

The FMMT449 is rated for 2 A continuous collector current under specified thermal conditions: mounted on a 4.5″ × 5″ FR-4 PCB with a 0.02 in² 2 oz copper pad. This rating assumes ambient temperature ≤25°C and accounts for the device's 500 mW total dissipation limit and 250°C/W junction-to-ambient thermal resistance. Exceeding 2 A requires derating or enhanced cooling.

Does FMMT449 have a guaranteed minimum DC current gain (h_FE) at 1 A collector current?

Yes, the FMMT449 guarantees h_FE ≥ 70 at I_C = 1 A, V_CE = 2 V, and T_A = 25°C. This minimum gain is confirmed across production lots and supports robust base drive design for saturation in load-switching applications. The datasheet also specifies h_FE ≥ 40 at I_C = 2 A, ensuring usable gain even near maximum current.

What is the typical saturation voltage V_CE(sat) of FMMT449 at 1 A collector current?

The FMMT449 has a maximum V_CE(sat) of 500 mV at I_C = 1 A and I_B = 100 mA. Typical values measured under these conditions are approximately 350–400 mV. This low saturation voltage directly reduces conduction losses in high-current switching paths, making the FMMT449 especially effective in battery-powered and thermally sensitive designs.

Is FMMT449 suitable for use in automotive under-hood applications?

Yes, the FMMT449 supports junction temperatures from –55°C to +150°C and is qualified for industrial and automotive under-hood environments when properly heatsinked. Its SuperSOT™-3 package and Process NB fabrication deliver stable electrical characteristics across this range. However, it is not AEC-Q101 qualified, so system-level validation is required for safety-critical automotive functions.

What package type does FMMT449 use, and how does it differ from standard SOT-23?

FMMT449 uses the SuperSOT™-3 package - a proprietary Fairchild/ON Semiconductor variant of SOT-23 with an enlarged exposed emitter pad for improved thermal conduction. While pin-compatible with SOT-23 footprints, SuperSOT™-3 achieves R_θJA = 250°C/W versus ~350°C/W for standard SOT-23, enabling higher continuous current capability without board redesign.

FMMT449 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

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):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 200mA, 2A

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 500mA, 2V

Power - Max:: 500 mW

Frequency - Transition:: 150MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

FMMT449 FAQ

1.How can I place an order for FMMT449 through Aetrix?

Please submit a Request for Quotation (RFQ) for FMMT449 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 FMMT449 reliable?

The price and inventory of FMMT449 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FMMT449 is usually 5 days.

3.What payment methods are accepted for FMMT449?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FMMT449 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FMMT449?

FMMT449 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FMMT449 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 FMMT449?

For technical support, including FMMT449 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FMMT449 requirements.

6.How does Aetrix verify that FMMT449 is sourced from the original manufacturer or authorized distributors?

All FMMT449 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 FMMT449 meets industry standards.

7.What is the process for return or replacement of FMMT449?

All FMMT449 units undergo pre-shipment inspection (PSI). If there is an issue with FMMT449, 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 FMMT449 part is unused and in its original packaging.

Return procedure for FMMT449:

1.Submit a request within 90 days.

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

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