MJE340G ,It is a medium-power, high-voltage NPN Bipolar Junction Transistor (BJT) manufactured by companies such as onsemi (formerly ON Semiconductor) and STMicroelectronics.The "G" at the end indicates that the part is a lead-free (Pb-free / RoHS compliant) package, meeting environmental standards. • Transistor Type: NPN • Package Type: TO-126 / TO-225AA (Thermopad structure suitable for cooler mounting) • Collector-Emitter Voltage (\(V_{CEO}\)Maximum voltage :300 V(High voltage resistance is its most prominent feature) • Continuous Collector Current (\(I_{C}\)) :Maximum500 mA (0.5A) • Maximum Power Consumption (\(P_{D}\)Power : 20 W(with a suitable heatsink/cooler) • DC Current Gain\(h_{FE}\)) : Between 30 and 240 (\(I_C = 50\text{ mA}\) ,\(V_{CE} = 10\text{ V}\) while) • Transition Frequency (\(f_{T}\)) : ~10 MHz