MMBT4401LT1G - 40V 600mA NPN Switching Transistor SOT-23
MPN: MMBT4401LT1G ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.18 | $0.18 |
| 10 | $0.14 | $1.40 |
| 100 | $0.08 | $8.00 |
| 500 | $0.05 | $25.00 |
| 1,000 | $0.04 | $40.00 |
| 3,000 | $0.03 | $90.00 |
MMBT4401LT1G Overview
A bipolar junction transistor is a three-terminal semiconductor device that uses a small base current to control a much larger collector current, enabling amplification and switching. BJTs occupy the hypernym hierarchy bipolar transistor -> transistor -> discrete semiconductor -> semiconductor, and NPN variants such as the MMBT4401LT1G are the most common polarity used in low-voltage DC and digital-interface circuits. The 2N4401 is the through-hole legacy equivalent of this part, and the MMBT prefix designates the SOT-23 surface-mount form factor.
Key features include a 40 V collector-emitter voltage (VCEO), 60 V collector-base voltage (VCBO), 6 V emitter-base voltage (VEBO), 600 mA continuous collector current, and a 200 mA saturation current rating that supports low-side load switching. The device is Pb-free, halogen-free/BFR-free, and the SMMBT4401LT1G variant carries AEC-Q101 qualification and PPAP capability for automotive applications requiring unique site and control change requirements.
The MMBT4401LT1G uses an epitaxial planar NPN silicon die with self-aligned geometry that yields tight beta spread and low saturation voltage (VCE(sat) typically 0.4 V at IC=150 mA). The SOT-23 package provides a thermal resistance of approximately 625 C/W (junction to ambient on a standard 1 oz copper test board), which limits continuous dissipation but is acceptable for pulsed switching duty cycles typical of interface and driver circuits.
Typical applications include low-side switching of relays, LEDs and small solenoids, level shifters between 3.3 V microcontrollers and 5 V or 12 V loads, signal inversion, interface buffers, and general-purpose DC amplification in consumer electronics. It is also commonly used as a discrete inverter in 3.3 V to 5 V logic translation circuits.
When designing with this device, ensure base drive current is at least 1/10th of the desired collector current to guarantee saturation. For switching loads above 100 mA, place a flyback diode across inductive loads and respect the 300 mW continuous power dissipation limit by either derating at elevated ambient temperatures or by using pulsed operation.
This page synthesizes distributor pricing, drop-in alternative MPNs in the same SOT-23 footprint, and practical design notes not found in the manufacturer datasheet, giving procurement and design engineers a single-source decision aid.
Drop-in alternatives for MMBT4401LT1G — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SMMBT4401LT1G
✅ Drop-In📋 Reference alternative (not in catalog)
MMBT4401LT1
✅ Drop-In📋 Reference alternative (not in catalog)
MMBT4401
✅ Drop-In📋 Reference alternative (not in catalog)
MMBT4401
✅ Drop-In📋 Reference alternative (not in catalog)
PMBT4401
✅ Drop-In📋 Reference alternative (not in catalog)
MMBT4401
✅ Drop-In📋 Reference alternative (not in catalog)
MMBT4401LT1G Maximum Ratings & Electrical Characteristics
| Transistor Type | NPN Bipolar Junction Transistor |
| Package | SOT-23-3 (TO-236) |
| Mounting Type | Surface Mount |
| Collector-Emitter Voltage (Vceo) | 40 V |
| Collector-Base Voltage (Vcbo) | 60 V |
| Emitter-Base Voltage (Vebo) | 6 V |
| Continuous Collector Current (IC) | 600 mA |
| Power Dissipation (Pd) | 300 mW |
| Transition Frequency (ft) | 250 MHz |
| DC Current Gain (hFE) Min | 100 (at IC=150 mA, VCE=1 V) |
| Operating Temperature Range | -55C to +150C |
| Pin Count | 3 |
| RoHS Status | Compliant |
| Lead-Free / Halogen-Free | Yes / Yes |
| AEC-Q101 Qualified Variant | SMMBT4401LT1G (S-prefix) |
MMBT4401LT1G Pin Configuration
| Pin 1 | Base — Base control terminal; controls collector current via IB |
| Pin 2 | Emitter — Emitter terminal; typically tied to GND for low-side switching |
| Pin 3 | Collector — Collector terminal; load current path; tied to load |
Typical Applications
MMBT4401LT1G is suitable for 7 applications: Low-Side Relay Driver, 3.3V to 5V Logic Level Shifter, LED Driver and Indicator Switch, Signal Amplifier / General-Purpose Amplification, Portable / Battery-Powered Consumer Electronics, Automotive Body Electronics and Lighting Modules, Interface Buffer and Inverter for Microcontroller I/O.
Low-Side Relay Driver
The MMBT4401LT1G is widely used as a low-side switch for 12 V automotive relays and small signal relays in industrial control panels. With 40 V VCEO headroom and 600 mA continuous collector current, the device tolerates the inductive flyback of a relay coil when a flyback diode (such as 1N4148) is placed across the coil. A base drive of 5-10 mA from a 5 V microcontroller GPIO through a 1 kohm resistor reliably saturates the transistor at 200-400 mA collector current. Compared to a MOSFET solution, the BJT offers lower cost, simpler drive (no gate charge management), and predictable saturation at sub-amp currents.
Recommended
3.3V to 5V Logic Level Shifter
The MMBT4401LT1G is commonly used as a discrete inverter / level shifter between 3.3 V microcontroller logic and 5 V peripheral loads. The transistor pulls the output low through the collector when the base is driven high by the 3.3 V GPIO, and the collector pull-up resistor (typically 10 kohm to 5 V) provides the high level. With 250 MHz fT the level shifter handles signals well into the MHz range, and the 6 V VEBO rating accepts 3.3 V base drive without series attenuation. Compared to a dedicated level-shifter IC, this discrete approach costs under $0.05 per channel and supports bidirectional open-drain translation with a second device.
Recommended
LED Driver and Indicator Switch
The MMBT4401LT1G functions as a constant-current sink or low-side switch for driving indicator LEDs and LED arrays in consumer and industrial products. With 600 mA IC rating, the transistor easily drives a single high-brightness LED at 20-150 mA with a series resistor, or multiplexed LED matrix rows in small displays. The 40 V VCEO is comfortable for 12 V LED strings and indicator lamps. Compared to a MOSFET, the BJT provides more linear base-emitter characteristic that simplifies analog dimming applications, and the SOT-23 footprint allows dense PCB placement.
Recommended
Signal Amplifier / General-Purpose Amplification
The MMBT4401LT1G serves as a general-purpose linear amplifier in audio preamplifier stages, sensor signal conditioning, and small-signal RF amplifier blocks where its 250 MHz transition frequency provides ample bandwidth. With a minimum hFE of 100 at 150 mA, the device offers strong gain in common-emitter configurations, and the low-noise epitaxial planar die supports moderate signal-to-noise requirements. Compared to a dedicated op-amp, this discrete BJT solution handles higher output swings, operates from a single supply, and costs a fraction of an integrated alternative for non-precision applications.
Recommended
Portable / Battery-Powered Consumer Electronics
The MMBT4401LT1G is found in portable devices such as toys, remote controls, and handheld instruments where its low cost, small SOT-23 footprint, and 300 mW dissipation rating are well-matched to battery-powered design constraints. The device switches at microamp-level base drive, preserving battery life, and its 600 mA peak current capability is sufficient for buzzers, small motors, and IR LED drivers. Compared to a logic-level MOSFET, this BJT operates at logic-compatible base voltages (3.3 V and 5 V) without requiring a charge pump or gate-driver circuit.
Recommended
Automotive Body Electronics and Lighting Modules
The automotive-grade SMMBT4401LT1G variant is qualified to AEC-Q101 and supports PPAP, making it suitable for body-electronics modules such as interior lighting, door-lock drivers, and HVAC panel controls. The 40 V VCEO and 600 mA IC rating comfortably handle small lamp and solenoid loads on the 12 V automotive bus, and the -55C to +150C operating junction range covers under-hood thermal stress. Compared to the industrial-grade MMBT4401LT1G, the SMMBT4401LT1G variant provides traceable manufacturing change control and is the required choice for OEM automotive platforms.
Recommended
Interface Buffer and Inverter for Microcontroller I/O
The MMBT4401LT1G functions as a discrete inverter or line driver for microcontroller GPIO expansion, particularly when a system needs additional current beyond the 20-40 mA source capability of typical MCU pins. With hFE of 100-300, the transistor buffers logic signals up to 600 mA, enabling direct drive of power MOSFETs, optocouplers, and optoisolators. The 250 MHz fT preserves signal rise/fall times for PWM signals into the MHz range. Compared to a MOSFET gate driver IC, this discrete BJT approach is the lowest-cost way to add current gain to a logic output.
Recommended
Recommended Products Summary
Engineering reference data for MMBT4401LT1G — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SMMBT4401LT1G | MMBT4401LT1 | MMBT4401 (Diodes Inc) | MMBT4401 (Vishay) | PMBT4401 | MMBT4401 (ROHM) |
|---|---|---|---|---|---|---|---|
| Package | SOT-23-3 (TO-236) | SOT-23-3 (TO-236) - same | SOT-23-3 (TO-236) - same | SOT-23-3 - same | SOT-23-3 - same | SOT-23-3 - same | SOT-23-3 - same |
| Brand | onsemi | onsemi | onsemi | Diodes Incorporated | Vishay Intertechnology | NXP Semiconductors | ROHM Semiconductor |
| VCEO (V) | 40 V | 40 V | 40 V | 40 V | 40 V | 40 V | 40 V |
| Continuous IC (mA) | 600 mA | 600 mA | 600 mA | 600 mA | 600 mA | 600 mA | 600 mA |
| Transition Frequency fT (MHz) | 250 MHz | 250 MHz | 250 MHz | 250 MHz | 250 MHz | 250 MHz | 250 MHz |
| AEC-Q101 Qualified | No (SMMBT variant qualified) | Yes | No | No | No | No | No |
| Pinout (1=B, 2=E, 3=C) | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- Automotive-grade qualified variant available in same SOT-23 footprint (vs MMBT4401 (Diodes Incorporated / Vishay))
- Industry-standard MMBT4401 nomenclature (vs MMBT4401LT1 (onsemi without G suffix))
- Wide cross-brand second-source availability (vs Niche SOT-23 NPN transistors)
Design Notes
The MMBT4401LT1G SOT-23 package has a thermal resistance of approximately 625 C/W (junction to ambient on a standard 1 oz copper 1 square inch test pad), which limits continuous power dissipation to 300 mW at 25C ambient. Estimated: at 50C ambient the maximum dissipation drops to approximately 200 mW. For switching loads above 100 mA, either derate the collector current or place the device on a thermal via array / copper pour to keep junction temperature below 150C. Below 200 mA load current and pulse widths under 100 ms the device typically runs well below thermal limits.
Do not exceed the 6 V VEBO rating by applying reverse base-emitter voltage. If the base can be driven below ground (for example in a high-side PNP-style driver circuit), add a base-emitter resistor of 10 kohm to limit reverse leakage. Also note that at very low collector currents (below 1 mA) hFE drops sharply - if your design depends on gain at sub-milliamp operation, consider a small-signal transistor such as BC847C or 2N3904 which has guaranteed gain at lower currents.
Place the base series resistor as close to the MMBT4401LT1G base pin as practical to limit parasitic oscillation at high dV/dt switching edges. Keep the collector trace short and wide enough to carry the load current without significant voltage drop. For switching above 100 mA at frequencies above 100 kHz, add a small RC snubber (100 ohm + 100 pF) from base to emitter to prevent ringing. The SOT-23 thermal pad (when present) should be soldered to a copper pour to maximize heat dissipation.
Estimated: a saturated switch at VCE(sat) of approximately 0.4 V at 200 mA collector current dissipates roughly 80 mW - well within the 300 mW rating. Verify saturation by ensuring base current is at least IC/10 (hFE=100 minimum). For switching inductive loads (relays, solenoids, motors) always place a flyback diode (1N4148 for small relays, or a Schottky such as B5819W for faster turn-off) across the load to clamp inductive kick below VCEO of 40 V.
Compliance Information
Pb-free and halogen-free per onsemi G-suffix convention. AEC-Q101 qualification and PPAP capability available on SMMBT4401LT1G (S-prefix) variant per onsemi datasheet.