onsemi MMBT4401WT1

Overview

MMBT4401WT1 from onsemi is an NPN silicon switching transistor in SC-70 (SOT-323) package, rated for 40 V_CEO, 600 mA continuous collector current, and 150 mW power dissipation at 25°C. It delivers DC current gain (h_FE) from 20 to 300 across 0.1–500 mA I_C, with f_T = 250 MHz and V_CE(sat) ≤ 0.75 V at I_C = 500 mA/I_B = 50 mA - used in low-voltage digital logic interface and load switching circuits.

For engineers reviewing the MMBT4401WT1 datasheet, pinout, applications, or equivalent options, key selection criteria include its 150 mW thermal limit on FR-5 board, 833°C/W R_JA, AEC-Q101 qualification (NSV prefix variant), and verified switching performance with t_d ≤ 15 ns, t_r ≤ 20 ns, t_s ≤ 225 ns under 30 V/150 mA conditions.

Technical Context

The MMBT4401WT1 operates as a general-purpose NPN bipolar junction transistor optimized for medium-speed switching in space-constrained applications. Its h_FE variation (20–300) is explicitly characterized across five I_C test points, and its small-signal parameters - h_ie (1.0–15 kΩ), h_fe (40–500), h_re (0.1–8.0 × 10⁻⁴), and h_oe (1.0–30 mhos) - are specified at 1 kHz, 10 V_CE, and 25°C.

Switching behavior is validated using standardized test circuits with defined V_CC = 30 V, I_C/I_B = 10, and pulse conditions (300 µs width, 2% duty cycle). Capacitance values - C_cb ≤ 6.5 pF and C_eb ≤ 30 pF - support stable operation up to 250 MHz f_T, while thermal limits (T_J = −55 to +150°C) enable use in automotive and industrial ambient environments.

Key Specifications

Pinout & Package

MMBT4401WT1 uses the SC-70 (SOT-323) surface-mount package (Case 419, Style 3), measuring 2.2 mm × 1.35 mm × 0.95 mm with gull-wing leads. Thermal resistance is 833°C/W (junction-to-ambient, FR-5 board), and the device is Pb-free, halogen-free, and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT4401LT1 and BC847BW, the MMBT4401WT1 uniquely balances ultra-small SC-70 size, AEC-Q101 compliance, and 250 MHz f_T - making it optimal for space-constrained automotive and industrial switching where thermal budget is tight and frequency response matters.

Availability

MMBT4401WT1 is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor interfaces, and portable LED lighting systems requiring stable component supply and long-term lifecycle support.

Supply support for MMBT4401WT1 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, medical, and IoT markets.

The MMBT4401WT1 belongs to onsemi's general-purpose bipolar transistor family designed for reliable, low-cost switching and amplification in high-volume consumer, industrial, and automotive electronics - emphasizing manufacturability, qualification, and thermal robustness in miniature packages.

FAQ

What is the maximum continuous collector current rating for MMBT4401WT1?

The MMBT4401WT1 has a maximum continuous collector current (I_C) rating of 600 mA at T_A = 25°C. However, practical operation at 500 mA requires verification of V_CE(sat) ≤ 0.75 V and thermal derating based on R_JA = 833°C/W. At elevated ambient temperatures or on non-FR-5 boards, the usable I_C must be reduced to maintain junction temperature below 150°C. The MMBT4401WT1 datasheet specifies absolute maximum ratings, not recommended operating conditions.

Is MMBT4401WT1 suitable for automotive applications?

Yes - the NSV-prefixed variant (NSVMMBT4401WT1G) is AEC-Q101 qualified and PPAP capable, meeting automotive reliability requirements for temperature cycling, humidity, and mechanical shock. The standard MMBT4401WT1G shares identical electrical and thermal specifications but lacks formal automotive certification documentation. For production automotive use, specify the NSV prefix version; the MMBT4401WT1 itself is commonly used in industrial and commercial designs where AEC-Q101 is not mandated.

What is the pin configuration of MMBT4401WT1 in SC-70 package?

The MMBT4401WT1 uses SC-70 (SOT-323) package with pin 1 = Base, pin 2 = Emitter, pin 3 = Collector - confirmed by onsemi's marking diagram and mechanical outline (Case 419, Style 3). This pinout differs from SOT-23 variants like MMBT4401LT1 (pin 1 = Emitter), so PCB layout must match SC-70 footprint. The device marking "MMBT4401WT1G" appears adjacent to pin 1, and the package is Pb-free with optional microdot or "G" suffix indicating RoHS compliance.

How does the h_FE variation affect circuit design with MMBT4401WT1?

The MMBT4401WT1 exhibits wide h_FE spread - 20 to 300 depending on I_C - meaning circuit gain and saturation behavior vary significantly across units. Designers must use forced beta (I_B/I_C ≥ 1/10) to ensure saturation across all bins, or implement emitter degeneration for linear amplification. The datasheet provides curves for high- and low-gain units selected from MMBT4401WT1 lines, confirming this spread is intentional and production-validated. For MMBT4401WT1, avoid relying on minimum h_FE alone in switching designs.

What are the thermal limitations of MMBT4401WT1 on a standard PCB?

On FR-5 board at T_A = 25°C, the MMBT4401WT1 dissipates up to 150 mW before exceeding its 150°C maximum junction temperature. With R_JA = 833°C/W, each 1°C rise in ambient reduces allowable power by ~0.18 mW. At 85°C ambient, maximum safe dissipation drops to ~35 mW - limiting continuous I_C to ~100 mA with V_CE(sat) ≈ 0.4 V. Layout enhancements (copper pour, thermal vias) improve R_JA, but the MMBT4401WT1 has no exposed thermal pad, so gains are modest versus larger packages.