MMBT3904LT1G Transistor | Datasheet, Spice Model & On Semi onsemi

MMBT3904LT1G

The MMBT3904LT1G transistor is a small NPN transistor that’s very common in electronics projects. It comes in a compact SOT-23 surface-mount package, making it easy to solder and integrate into your circuit.

Specifically, it’s quite durable: it can handle voltages up to about 40 volts between the collector and emitter, and comfortably manage currents around 200mA. It’s ideal for small switching tasks or simple amplification circuits. Plus, its typical gain (hFE) ranges roughly between 100 and 300, and it supports operation at relatively high frequencies, around 250 MHz.

MMBT3904LT1G pinout and marking

MMBT3904LT1G replacement transistor

When selecting a replacement for the MMBT3904LT1G, ensure that the substitute transistor matches or exceeds the original’s specifications, particularly in terms of voltage (VCEO), current (IC), and power dissipation (PD). Also, consider the hFE (DC current gain) and transition frequency (fT) to ensure compatibility with your application’s requirements. Always verify the pin configuration and package type to ensure a proper fit in your circuit.

MMBT3904LT1G switching circuit design

Circuit Components:

• NPN Transistor: MMBT3904LT1G, used as the switching device.

• Resistor R1: Acts as a current-limiting resistor for the load. Its value depends on the load current and the supply voltage.

• Resistor R2: Provides current-limiting protection for the transistor’s base. Typically, R2 ranges from a few hundred ohms to several kilo-ohms to prevent excessive base current.

• Input Signal: Controls the ON/OFF state of the transistor.

Working Principle:

• When the input signal is HIGH (positive voltage): Current flows into the transistor’s base (B) through resistor R2. This forward-biases the transistor’s base-emitter junction, causing the transistor to turn on (saturate). Consequently, the transistor’s collector (C) and emitter (E) become conductive, allowing current to flow through resistor R1 and the load.

• When the input signal is LOW (ground or zero voltage): No base current flows into the transistor, leaving it turned off. The transistor remains in a high-impedance state, disconnecting the load from the circuit.

MMBT3904LT1G vs mmbt2222a comparison

• MMBT3904LT1G is typically used for low-current, small-signal amplification and switching applications.

• MMBT2222A offers higher current handling capabilities, making it suitable for medium-current amplification and general-purpose switching circuits.

MMBT3904LT1G led driver application

MMBT3904LT1G is a small-signal NPN transistor typically packaged in a SOT-23 format. It can handle a maximum continuous collector current (I_C) of 200 mA and features a maximum power dissipation rating of 225 mW. This makes it suitable for low-current switching tasks, signal amplification, and small load applications. For reliable operation, it’s important to avoid exceeding these current ratings to prevent transistor damage or reduced reliability.

MMBT3904LT1G current handling specs

The MMBT3904LT1G is a small NPN transistor widely used in LED driver applications. In these circuits, it typically functions as a simple electronic switch. When a microcontroller or logic circuit outputs a HIGH-level signal, the transistor turns on, allowing current to flow through the LED and lighting it up. Conversely, when the input signal is LOW, the transistor switches off, causing the LED to turn off as well. Such circuits are straightforward and efficient, making them ideal for applications like status indicator lights, backlighting, and display panel controls.