It is mostly used in embedded and automation projects.It is typically used in automation & embedded projects.It is used for PWM due to its quick response.As compared to the normal NPN BC547 transistor, the 2N2222 is extremely similar, but 2N2222 allows 800mA of collector current & also 652mW of power dissipation which can be utilized for driving larger loads as compared toBC547.Saturation Region is also primarily used in switching and digital logic circuits. The transistor is fully switched on in this mode, and the circuit is closed. With almost zero resistance, current flows freely from collector to emitter. The emitter-base and collector-base junctions are forward biased in this region. Switching and digital logic circuits are primarily used in the Cutoff Region. In this mode, the BJT is switched off and the circuit is an open circuit. There is no current flow except small leakage currents because both PN Junctions are reverse biased (usually in the order of a few nanoamps or pico amps). The collector-base junction and the emitter-base junction are reverse biased in this mode. Current flows between the emitter and the collector in this mode, with the amount of current flow proportional to the base current. Two junctions are biased differently in active mode, with the emitter-base junction being forward biased and the collector-base junction being reverse biased. The transistor is generally used as a current amplifier in this mode.

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