BD139 | Transistor Datasheet, Circuit Diagram & PDF STMicroelectronics

BD139 Circuit Diagram

BD139 is a kind of PNP transistor which is often used in a wide range of applications, such as switching circuits, power amplifier circuits, audio amplifier circuits and so on. The next section describes the BD139 principle of operation in detail.

Introduction to BD139

BD139 Pinout Diagram

The BD139 is a bipolar NPN transistor (BJT) in a TO-126 package that is primarily used in power amplification circuits, especially low and intermediate frequency amplification circuits. It can withstand large currents (maximum collector current of 1.5A) and voltages (maximum collector and emitter withstand voltages of 80V), making it ideally suited for driving high power loads. It also has a low saturation voltage drop and high switching speed, making it widely used in switching circuits as well. Thanks to good temperature characteristics (from -55 to +150°C) and stability, reliable performance is maintained even under extreme operating conditions.
The amplification range of BD139 is from 40 to 160, (this is the amplification capability of BD139), meaning that the current flowing from the base can be amplified by a maximum of 160 times, but from the datasheet, it can be seen that the current passing through the collector pin can not exceed 1.5A (if you leave a margin of twenty per cent according to that, i.e., it can not exceed 1.5*0.8=1.2), i.e., the current before amplification Can not exceed 1.2/160 (this should be calculated according to the specific amplification).

Application:

The figure is to use the amplification ability of BD139 to control the fan rotation. One of the 1k resistor is to limit the current, to prevent the base current is too large burned BD139; 1n4007 role is to play a protective role in preventing the power supply reversed damage to other components; 100uf capacitor role is to filter out the low-frequency noise in the circuit, so that the circuit works more stable.

BD139 USE Picture