Category: Transistor

Posted on by — Leave a comment

TIP3055 NPN BJT

It is a power transistor capable of handling power dissipation up to 90W for a few microseconds(generally less than 300 microseconds). Also, it has a Vceo of 60 V and a collector current of 15A.

TIP3055 is a widely used NPN power transistor that can handle high power and high voltage applications. It has a maximum collector-emitter voltage of 60V and a maximum collector current of 15A, making it ideal for use in power supplies, audio amplifiers, and motor control circuits. TIP3055 is a versatile transistor that can be used in a variety of circuit designs due to its high current gain and fast switching speeds. Its popularity can be attributed to its low cost, high reliability, and ease of use. With its ability to handle high power and voltage, TIP3055 is a go-to component for any circuit designer looking for a reliable power transistor.

It comes in a TO-247 package.
This is handy as it can be mounted to a heat sink with a nut bolt.

Datasheet Links

ST – https://www.st.com/resource/en/datasheet/tip3055.pdf

Onsemi – https://www.onsemi.com/pdf/datasheet/tip3055-d.pdf

Do all the companies that manufacture TIP3055 have exactly the same pinouts?

The TIP3055 transistor has a standardized pinout, which means that all manufacturers of this transistor must follow the same pinout configuration. The pinout configuration for the TIP3055 transistor is as follows:

  • Pin 1: Base
  • Pin 2: Collector
  • Pin 3: Emitter

Therefore, no matter which company manufactures the TIP3055 transistor, the pinout configuration should always be the same, and you can expect the same pinout configuration for TIP3055 transistors from different manufacturers. However, it is always recommended to check the datasheet provided by the manufacturer to confirm the pinout configuration and other specifications before using the transistor in a circuit.

Posted on by — Leave a comment

BD139 Pinout

The BD139 is a general-purpose NPN bipolar junction transistor (BJT). It has three pins:

  1. Base (B)
  2. Collector (C)
  3. Emitter (E)

There are two companies that manufacture the transistor

  1. STMicroelectronics
  2. onsemi

The pinout diagram according to STMicroelectronics is as follows:

When looking at the center hole and keeping the metal side down the pins are arranged from right to left as:

  1. Base (B)
  2. Collector (C)
  3. Emitter (E)

It’s important to note that the metal tab is connected to the Collector pin.

The pinout diagram according to ON Semiconductor is as follows:

When looking at the flat side of the transistor with the pins facing down and the metal tab facing up, the pins are arranged from left to right as follows:

  1. Emitter (E)
  2. Collector (C)
  3. Base (B)

It’s important to note that the metal tab is connected to the Collector pin.

Posted on by — Leave a comment

Power Bipolar Transistors are limited by DC operations.

Power transistors are big bulky because they have to deal with a large amount of current in a very short amount of time. They are the fastest of all the transistors.

Heat is the biggest enemy of the transistor. As silicon is heavily dependent on temperature. As the die temperature increases the more sensitive it becomes. And at a certain point, it burns out. At the moment of burning there is a short which generates so much heat that the silicon just burns itself off.

Even the TIP3055 can only handle instantaneous current pulses for a very short amount of time. If that same transistor is put under a continuous load it will burn out in a few instances.

If we look at the derating curve of any power transistor. We will find out that they are only good for up to 1Amps of DC operation. And even at 1 Amp, it will need a sizeable amount of aluminium heatsink.

Posted on by — Leave a comment

FAKE BD139 NPN transistors

I have recently found out that there are FAKE transistors in the market. I have a built a circuit design and when I bought the transistor from the Lajpat rai market in Delhi; I assembled the circuit on a test bench for measurements. But I was surprised that the BD139 did not work with 10mA at 30V and they began overheating. They heat up so much that bubbles appear on the front epoxy and it cracked. I thought that maybe it was damaged so I replaced the whole circuit with a new transistor set. But they also didn’t hold and this time they burnt a resistor along with them. I saw flames engulfing the 1/4 Watt resistors.

So I again made the circuit using the minuscule BC546B. Which neither get warm nor went into thermal runaway.

on the BD139 it was marked that it was manufactured by NXP. And I then checked the NXP website and found out that the NXP closed its manufacturing of this transistor in 2001.

There are a lot of BD139 transistors circulating in the market. It is essential that you must buy from a good source.