Infineon MMBT2222ALT1HTSA1 NPN Bipolar Junction Transistor: Datasheet, Pinout, and Application Notes

The Infineon MMBT2222ALT1HTSA1 is a widely used NPN Bipolar Junction Transistor (BJT) housed in a compact SOT-23 surface-mount package. As a member of the ubiquitous 2N2222 family, this component is renowned for its general-purpose amplification and low-power switching capabilities. Its small form factor and reliable performance make it a common choice in modern electronic design for consumer, industrial, and automotive applications.

Datasheet Overview: Key Specifications

A thorough review of the datasheet reveals the electrical characteristics that define the transistor's operation:

Polarity: NPN

Collector-Emitter Voltage (V_CEO): 40 V – a key rating for switching inductive loads.

Collector Current (I_C): 600 mA (continuous) – suitable for driving relays, LEDs, and small motors.

DC Current Gain (h_FE): Typically 100 to 300 at 10 mA, 10 V, ensuring good amplification.

Power Dissipation (P_tot): 330 mW at 25°C, which is critical for thermal management.

Transition Frequency (f_T): 300 MHz minimum, indicating its usefulness in high-speed switching and RF amplification applications.

These parameters are essential for determining the transistor's suitability for a specific circuit, ensuring it operates within its Safe Operating Area (SOA).

Pinout (SOT-23 Package)

Correct connection is vital. The pinout for the SOT-23 package is as follows:

1. Pin 1 (Emitter): This is the source of electrons. It is typically connected to ground or the common low-voltage point in a circuit.

2. Pin 2 (Base): This is the control terminal. A small current applied here controls a larger current flow between the collector and emitter.

3. Pin 3 (Collector): This terminal collects the charge carriers. It is usually connected to the load being switched and the positive supply rail.

Application Notes

The MMBT2222ALT1HTSA1 excels in two primary functions:

1. Switching Mode: As an low-side switch, it is highly effective for controlling loads like LEDs, relays, or motors. A key design consideration is using a base resistor to limit the current into the base pin, ensuring it is driven into saturation for minimal voltage drop (V_CE(sat)) across the collector and emitter. A flyback diode is mandatory when switching inductive loads to protect the transistor from voltage spikes.

2. Amplification Mode: In amplifier circuits (common-emitter, common-collector), it is used to amplify small AC signals. Biasing the transistor correctly with resistor networks at the base is crucial to set the operating point (Q-point) in the linear region of its characteristics. Its high f_T makes it suitable for pre-amplifier stages in audio and RF applications.

ICGOODFIND: The Infineon MMBT2222ALT1HTSA1 stands as a robust and versatile SMD successor to the through-hole 2N2222. Its well-balanced specifications for voltage, current, and speed, combined with Infineon's quality and reliability, make it an excellent choice for designers seeking a dependable general-purpose NPN transistor for a vast array of circuit functions, from simple switching to signal amplification.

Keywords: NPN Transistor, SOT-23, Switching, Amplification, Datasheet