Diodes Incorporated MMBT3904-7-F

Overview

MMBT3904-7-F from Diodes Incorporated is a 40 V, 200 mA NPN small-signal transistor in SOT23 package, optimized for medium-power amplification and switching functions with h_FE = 100–300 at I_C = 10 mA, V_CE = 1.0 V, and V_CE(sat) ≤ 0.20 V at I_C = 10 mA / I_B = 1.0 mA. It serves as a general-purpose gain stage or digital switch in low-voltage logic interfaces, sensor signal conditioning, and LED driver bias circuits.

For engineers reviewing the MMBT3904-7-F datasheet, MMBT3904-7-F pinout, MMBT3904-7-F application, or MMBT3904-7-F equivalent, key selection criteria include DC current gain linearity across 0.1–100 mA collector current, low saturation voltage under defined drive conditions, thermal resistance (R_θJA = 403 °C/W on minimum pad layout), and ESD robustness (HBM = 4 kV).

Technical Context

This NPN bipolar junction transistor operates in active, saturation, and cutoff regions with verified DC gain (h_FE) spanning 40–300 across I_C = 100 µA to 100 mA and V_CE = 1.0 V. Its f_T = 300 MHz supports RF preamplifier use up to VHF band when biased at I_C = 10 mA, V_CE = 20 V.

Switching performance is characterized by td/tr/ts/tf = 35/35/200/50 ns under V_CC = 3.0 V, I_C = 10 mA, and I_B1 = I_B2 = 1.0 mA. C_obo = 4.0 pF and C_ibo = 8.0 pF at specified reverse-bias conditions confirm suitability for <100 MHz signal routing where parasitic capacitance must remain below 10 pF.

Key Specifications

Pinout & Package

Package: SOT23 - Surface-mount plastic package with 3-terminal leadframe, 0.008 g mass, UL 94V-0 flammability rating, and matte tin-plated leads solderable per MIL-STD-202 Method 208.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN small-signal transistor applications.

Compared with BC847B,215 and PN2222A, MMBT3904-7-F delivers optimal balance of SOT23 footprint compatibility, 310 mW power dissipation, and tightly specified V_CE(sat) for high-efficiency switching in volume production PCBs.

Availability

MMBT3904-7-F is available at Aetrix Electronics and suitable for LED driver bias stages, microcontroller GPIO interfaces, sensor signal conditioning, and low-voltage power switches requiring stable component supply and full RoHS 3 compliance.

Supply support for MMBT3904-7-F 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, specializing in high-reliability components for industrial, computing, consumer, and automotive markets.

The MMBT3904 belongs to Diodes' general-purpose small-signal transistor product line, engineered for cost-sensitive, high-volume applications demanding consistent gain, low saturation voltage, and robust ESD protection.

FAQ

What is the maximum continuous collector current for MMBT3904-7-F?

The absolute maximum continuous collector current is 200 mA at T_A = +25°C. Derating applies above 25°C ambient per the published thermal resistance (R_θJA = 403 °C/W) and power dissipation limit (P_D = 310 mW on minimum pad layout). At 75°C ambient, maximum usable I_C drops to approximately 140 mA assuming V_CE(sat) remains constant.

Is MMBT3904-7-F suitable for automotive applications?

The standard MMBT3904-7-F is not AEC-Q101 qualified. However, Diodes offers the MMBT3904Q variant, which undergoes automotive-grade stress testing and is documented in a separate datasheet. For production automotive systems, MMBT3904Q must be specified; the -7-F version is intended for industrial, consumer, and computing applications.

How does the h_FE variation affect base resistor selection?

h_FE ranges from 40 to 300 depending on I_C and test condition. For reliable saturation at I_C = 10 mA, design for h_FE(min) = 40 at that current - requiring I_B ≥ 250 µA. Using h_FE = 100 as a typical value yields I_B = 100 µA, but worst-case analysis mandates the minimum gain to ensure V_CE(sat) stays within spec.

What is the recommended PCB pad layout for thermal performance?

Diodes specifies two thermal test conditions: minimum recommended pad layout (R_θJA = 403 °C/W) and 15 mm × 15 mm 1 oz copper (R_θJA = 357 °C/W). The minimum layout uses 2.0 mm × 0.8 mm pad dimensions with 1.35 mm X1 spacing. Full thermal performance requires adherence to the SOT23 outline drawing and avoiding excessive copper removal near the device body.