2N3055 Power Transistor Technical Specifications
The 2N3055 transistor is a silicon NPN power transistor intended for general purpose applications. It was introduced in the early 1960's by RCA using their "hometaxial" power transistor process. It was one of the first silicon power transistors, offered unrivalled second breakdown immunity and found many applications particularly in audio power amplifiers and linear power supplies.
The exact specs depend on the manufacture, it is important to reference the datasheet for the exact device and brand you are dealing with.
Packaged in a TO3 can, it is a 15A amp, 60V volt, 115W watt power transistor with a Beta of 20 to 70 at a collector current of 4A. It gained popularity because it had 100 % safe-operating-area, (SOA), meaning that it could dissipate 115W at a collector voltage of 60V (Ic=1.9A), provided the case temperature did not exceed 25 deg.C. It was designed for medium current and high power circuits. Commercially, it was used in many linear power supplies, audio amplifiers and low frequency power converters. One limitation was that its frequency response was rather slow (typically the unity-gain frequency was 1 MHz) The 2N3055 power transistor was the first multi-amp silicon transistor to sell for less than one dollar! It was a huge success in the power supply market..
With changes to the technology, the original process became uneconomical and a similar device, now using the name 2N3055 transistor, was supplied using epitaxial base technology. The maximum voltage and current ratings of this device are the same as the original, but the power handling (safe operating area) is limited at high voltage to a lower current than the original. However, the cut-off frequency is higher, so allowing the newer type of 2N3055 transistor to be more efficient in switching power supplies. Also the higher frequency response improves the performance when used in audio amplifiers. Some suppliers offer a high safe-operating-area version of the 2N3055 power transistor using the "H" suffix.
The 2N3054 transistor is a lower power version of the 2N3055 transistor, rated at 25W, 55V and 4A, but became almost obsolete about the late 1980's when many TO-66 devices were withdrawn from mainstream manufacturers's lists. In many cases a TO-220 packaged version, such as MJE3055T, can be used instead of the 2N3054 as well as in some 2N3055 power transistor applications. An MJ2955 is a complementary (PNP) transistor for the 2N3055 transistor, which is also manufactured using the epitaxial process today.