Transistor NPN BD139

• BD139 is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin. BD139 has a gain value of 40 to 160, this value determines the amplification capacity of the transistor. The maximum amount of current that could flow through the Collector pin is 1.5A, hence we cannot connect loads that consume more than 1.5A using this transistor. To bias a transistor we have to supply current to base pin, this current (IB) should be limited to 1/10th of the collector current and voltage across the base emitter pin should be 5V maximum. When this transistor is fully biased then it can allow a maximum of 1.5A to flow across the collector and emitter. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (V­CE) or Base-Emitter (VBE) could be 80V. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region.
• BD139 is a popular NPN transistor used in wide variety of electronic circuits, due to its high collector current and low cost it is an ideal transistor to be used in educational electronic projects and also in commercial electronics. It can drive loads upto 1.5A which is a good feature due to which you can drive many high current components such as high power LEDs, high current relays, motors etc. The collector emitter and collector base voltage is also very high therefore it can easily survive in an electronic circuit that is operated under 80 volts. The collector dissipation is 12.5W due to which it is also ideal to use it in audio amplifier circuits. The saturation voltage of the transistor is just 0.5V
• BD139 Equivalent NPN Transistors BD136, BD138
• BD139’s PNP Complementary is BD140

Applications

• RF Amplifiers
• Switching circuits
• Amplification circuits
• Audio amplifiers
• Load driver circuits