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

onsemi MMBT4401K

Name: MMBT4401K
Brand: onsemi
SKU: MMBT4401K
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBT4401K

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: MMBT4401K.pdf

Description:: TRANS NPN 40V 0.6A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MMBT4401K from Fairchild Semiconductor is an NPN epitaxial silicon switching transistor in SOT-23 package, rated for 40 V V_CEO, 600 mA I_C, and 350 mW P_C. It delivers h_FE = 100 at I_C = 150 mA and V_CE = 1 V, with t_ON/t_OFF of 35 ns/255 ns, enabling fast-switching operation in low-voltage digital logic interfaces and LED driver stages.

For engineers reviewing the MMBT4401K datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO = 40 V, guaranteed h_FE ≥ 80 at I_C = 10 mA, SOT-23 footprint compatibility, saturation voltage ≤ 0.4 V at I_C/I_B = 150 mA/15 mA, and operating junction temperature up to +150°C.

Technical Context

This discrete NPN bipolar junction transistor uses epitaxial base construction to achieve high-speed switching performance and stable DC current gain across temperature. Its design supports active-mode amplification and saturated-switching operation with defined V_BE(sat) and V_CE(sat) under controlled I_C/I_B ratios.

The device operates within a -55°C to +150°C junction temperature range and exhibits f_T = 250 MHz at I_C = 20 mA, V_CE = 10 V, confirming suitability for medium-frequency signal switching-not RF amplification-while Cob = 6.5 pF at V_CB = 5 V supports predictable capacitive loading in gate-drive or level-shift circuits.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum collector-emitter voltage before breakdown under open-base condition; defines safe switching voltage headroom in 24 V and lower systems.
I_C	600 mA - Continuous collector current rating; supports load switching up to ~500 mA with derating above 25°C ambient.
P_C	350 mW - Maximum power dissipation at T_A = 25°C; requires thermal design consideration above 75°C ambient per derating curve.
h_FE	100 (min) at I_C = 150 mA - Confirmed DC current gain ensures reliable saturation with I_B ≥ 15 mA for full-load switching.
V_CE(sat)	0.4 V max at I_C = 150 mA, I_B = 15 mA - Low saturation voltage minimizes conduction loss in high-duty-cycle digital output stages.
f_T	250 MHz - Current-gain bandwidth product confirms usable switching speed up to ~10–20 MHz square-wave operation.

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads, 1.90 mm × 1.30 mm body size, 0.95 mm lead pitch, and 0.45–0.60 mm lead thickness. Marked "2XK" on top surface.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal; requires ≥15 mA drive current to saturate at I_C = 150 mA per h_FE and V_BE(sat) specs.
2	Emitter	Current return path; internally connected to substrate; must be tied to lowest potential in common-emitter configuration.
3	Collector	Output terminal; carries switched load current; electrically isolated from package tab (no thermal pad).

Key Features

Feature	Design Value
Epitaxial base structure	Enables consistent h_FE and fast t_ON/t_OFF across production lots and temperature ranges.
Guaranteed h_FE ≥ 80 at I_C = 10 mA	Ensures robust turn-on margin in microcontroller GPIO-driven switch applications without external gain staging.
V_CE(sat) ≤ 0.4 V @ I_C/I_B = 150 mA/15 mA	Reduces power loss to <100 mW in saturated switching, supporting thermally constrained PCB layouts.
Operating T_J up to +150°C	Validates reliability in enclosed industrial enclosures or near heat-generating components without forced cooling.

Applications

LED Driver Stage	Digital Logic Level Shifting
Use Scenario: Driving 20–50 mA indicator LEDs from 3.3 V or 5 V MCU GPIO pins with current-limiting resistor. IC Role / Device Role / Timing Role: Discrete NPN switch providing low-side current sink with defined saturation behavior. Use Value: V_CE(sat) ≤ 0.4 V ensures >95% of supply voltage reaches LED, maximizing brightness consistency across batches.	Use Scenario: Translating 1.8 V logic-high signals to 5 V rail for legacy peripherals using open-collector interface. IC Role / Device Role / Timing Role: Active pull-up switch enabling bidirectional level translation with sub-40 ns turn-on delay. Use Value: t_ON = 35 ns supports clean signal integrity up to 10 Mbps UART or I²C clock stretching modes.
Relay Coil Driver	Small-Signal Amplifier Stage
Use Scenario: Switching 12 V, 400 mA relay coils in programmable logic controllers with flyback diode protection. IC Role / Device Role / Timing Role: Medium-current saturated switch handling repetitive inductive loads with defined energy dissipation limits. Use Value: 600 mA I_C rating and 350 mW P_C allow safe operation at 50% duty cycle with minimal heatsinking.	Use Scenario: Low-gain preamplifier for sensor signals in battery-powered environmental monitors. IC Role / Device Role / Timing Role: Linear-mode amplifier biased at I_C = 1 mA with h_FE ≥ 40 ensuring stable small-signal gain. Use Value: h_FE = 40 min at I_C = 1 mA enables predictable bias point setting without trimming resistors.

LED Driver Stage

Digital Logic Level Shifting

Use Scenario: Driving 20–50 mA indicator LEDs from 3.3 V or 5 V MCU GPIO pins with current-limiting resistor.

IC Role / Device Role / Timing Role: Discrete NPN switch providing low-side current sink with defined saturation behavior.

Use Value: V_CE(sat) ≤ 0.4 V ensures >95% of supply voltage reaches LED, maximizing brightness consistency across batches.

Use Scenario: Translating 1.8 V logic-high signals to 5 V rail for legacy peripherals using open-collector interface.

IC Role / Device Role / Timing Role: Active pull-up switch enabling bidirectional level translation with sub-40 ns turn-on delay.

Use Value: t_ON = 35 ns supports clean signal integrity up to 10 Mbps UART or I²C clock stretching modes.

Relay Coil Driver

Small-Signal Amplifier Stage

Use Scenario: Switching 12 V, 400 mA relay coils in programmable logic controllers with flyback diode protection.

IC Role / Device Role / Timing Role: Medium-current saturated switch handling repetitive inductive loads with defined energy dissipation limits.

Use Value: 600 mA I_C rating and 350 mW P_C allow safe operation at 50% duty cycle with minimal heatsinking.

Use Scenario: Low-gain preamplifier for sensor signals in battery-powered environmental monitors.

IC Role / Device Role / Timing Role: Linear-mode amplifier biased at I_C = 1 mA with h_FE ≥ 40 ensuring stable small-signal gain.

Use Value: h_FE = 40 min at I_C = 1 mA enables predictable bias point setting without trimming resistors.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN switching transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT2222A	V_CEO = 40 V, I_C = 600 mA, but h_FE = 100 min only at I_C = 150 mA; f_T = 300 MHz.	Higher f_T supports faster edge rates but tighter h_FE distribution at low I_C.	Prefer MMBT2222A when designing for >20 MHz switching or requiring tighter h_FE tolerance at I_C < 10 mA.
PN2222A	TO-92 package, same electrical specs, but P_C = 625 mW and slower t_OFF = 500 ns due to larger junction capacitance.	Through-hole mounting and higher power handling, but incompatible with SMT-only assembly.	Choose PN2222A only for prototyping, repair, or mixed-technology boards where SMT density is not required.

Compared with MMBT2222A and PN2222A, the MMBT4401K offers optimized h_FE linearity across 1–150 mA, fastest t_ON in its class, and strict SOT-23 footprint compliance-making it preferred for space-constrained, high-reliability digital switching where consistent saturation and thermal performance are critical.

Availability

MMBT4401K is available at Aetrix Electronics and suitable for LED driver stages, digital logic level shifting, relay coil driving, and small-signal amplifier applications requiring stable component supply across industrial control, instrumentation, and consumer electronics programs.

Supply support for MMBT4401K 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

Fairchild Semiconductor was a U.S.-based analog and discrete semiconductor manufacturer, acquired by ON Semiconductor in 2016; its legacy products remain widely supported and qualified for industrial use.

The MMBT4401K belongs to Fairchild's general-purpose bipolar transistor family designed specifically for cost-sensitive, high-volume switching applications where predictable gain, low saturation voltage, and SOT-23 manufacturability are essential.

FAQ

What is the maximum continuous collector current rating for MMBT4401K?

The MMBT4401K has a maximum continuous collector current (I_C) rating of 600 mA at T_A = 25°C. This rating decreases with rising ambient temperature per the derating curve in the datasheet, reaching approximately 300 mA at 75°C ambient. The MMBT4401K must be operated within this limit to avoid thermal runaway or permanent degradation.

Does MMBT4401K support switching at 10 MHz?

Yes, the MMBT4401K supports switching at 10 MHz in saturated mode due to its f_T = 250 MHz and t_ON/t_OFF = 35 ns/255 ns. However, practical square-wave operation at 10 MHz requires careful layout to minimize parasitic inductance and ensure adequate base drive. The MMBT4401K is not intended for linear RF amplification at this frequency.

What is the pin configuration of MMBT4401K in SOT-23 package?

The MMBT4401K uses standard SOT-23 pinout: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This matches JEDEC TO-236AB and is confirmed by Fairchild's mechanical drawing and marking "2XK" orientation. No alternate pinouts exist for this part number; incorrect orientation will result in circuit failure.

Is MMBT4401K suitable for automotive applications?

The MMBT4401K is not AEC-Q101 qualified and lacks automotive-grade screening or extended temperature validation beyond its specified -55°C to +150°C operating range. While it may function in non-safety-critical automotive subsystems, the MMBT4401K is intended for industrial, commercial, and consumer applications-not automotive safety or powertrain systems.

How does MMBT4401K compare to MMBT4403 in complementary pair usage?

The MMBT4401K (NPN) and MMBT4403 (PNP) form a complementary pair with matched V_CEO (40 V), I_C (600 mA), and package (SOT-23), but differ in h_FE profiles: MMBT4401K specifies h_FE ≥ 100 at I_C = 150 mA, while MMBT4403 specifies h_FE ≥ 50 at same conditions. The MMBT4401K thus provides higher gain in NPN roles, making it preferable for asymmetric drive requirements in push-pull outputs.

MMBT4401K 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):: 600 mA

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

Vce Saturation (Max) @ Ib, Ic:: 750mV @ 50mA, 500mA

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 150mA, 1V

Power - Max:: 350 mW

Frequency - Transition:: 250MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

MMBT4401K FAQ

1.How can I place an order for MMBT4401K through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBT4401K 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 MMBT4401K reliable?

The price and inventory of MMBT4401K are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBT4401K is usually 5 days.

3.What payment methods are accepted for MMBT4401K?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBT4401K transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBT4401K?

MMBT4401K orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBT4401K 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 MMBT4401K?

For technical support, including MMBT4401K datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBT4401K requirements.

6.How does Aetrix verify that MMBT4401K is sourced from the original manufacturer or authorized distributors?

All MMBT4401K 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 MMBT4401K meets industry standards.

7.What is the process for return or replacement of MMBT4401K?

All MMBT4401K units undergo pre-shipment inspection (PSI). If there is an issue with MMBT4401K, 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 MMBT4401K part is unused and in its original packaging.

Return procedure for MMBT4401K:

1.Submit a request within 90 days.

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

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