The MJE243G is an NPN Bipolar Transistor manufactured by ON Semiconductor. It is a 4 Amp, 100 Volt, 15 Watt device designed for use in switching, power bipolar transistor applications. This device has an integrated ECOPack packaging, and is capable of operating at temperatures up to 150 degrees Celsius. It has a wide range of features, including a low ON-state collector current, low ON-state voltage drop, and fast switching. The unit features a max surge rating of 500 Amps, and comes in a TO-270 plastic package.