MMBT2222ALT1G | Datasheet & PDF | SOT23 | On Semiconductor onsemi

MMBT2222ALT1G

The MMBT2222ALT1G is an NPN small-signal transistor in a compact SOT-23 surface-mount package. It supports a maximum collector-emitter voltage (VCEO) of 40V and a maximum collector current (IC) of up to 600mA. With a typical high gain (hFE) ranging from 100 to 300 and a fast switching speed (up to about 250MHz), it’s commonly used in low-power switching circuits, signal amplification, and for driving LEDs or small relays.

MMBT2222ALT1G pinout function

• When using the MMBT2222ALT1G as a switch or amplifier, ensure the base current is limited appropriately to avoid damage from excessive base-emitter current.

• The emitter typically connects to the circuit’s negative side (ground) or the lower side of the load, while the collector connects to the positive power supply or the upper side of the load.

MMBT2222ALT1G equivalent npn smd transistor

MMBT2222ALT1G amplifier circuit example

Circuit Components:

• Transistor T3: Acts as the input-stage common-emitter amplifier, responsible for initial voltage amplification of the audio signal.

• Transistors T4 and T5: Form a push-pull output stage, providing current amplification to directly drive the speaker.

• Diode D4 (1N4148): Provides bias voltage for transistors T4 and T5, ensuring stable operation and reducing crossover distortion.

• Resistor R6 (82kΩ) and Resistor R7 (1.8kΩ): Set the operating current and biasing for the input stage, stabilizing the amplifier’s operation point.

• Capacitor C3 (0.47μF) and Capacitor C6 (100μF): Serve as DC-blocking capacitors, allowing only AC audio signals to pass. Additionally, capacitor C6 smooths and filters the output signal to the speaker.

Working Principle:

• The audio input signal enters the base of transistor T3 through capacitor C3, undergoing initial voltage amplification.

• The amplified signal is then passed to the push-pull stage formed by T4 and T5. In this stage, one transistor conducts while the other remains off, effectively amplifying the current to power the speaker.

• Diode D4 provides stable biasing for the output transistors, significantly reducing distortion, particularly crossover distortion.

• The amplified audio signal passes through capacitor C6 to the speaker, generating sound.

MMBT2222ALT1G with arduino

The MMBT2222ALT1G is a small-signal NPN transistor commonly used with Arduino boards. You can easily use an Arduino digital output pin to control its base, allowing the transistor to function as an electronic switch. This lets you manage higher-power components such as LED strips, small motors, or buzzers. It’s a simple, affordable, and reliable option for driving various low-power loads in Arduino projects.