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BC557 Transistor: Pinout, Datasheet, Circuit [Video]

  • Contents

BC557 is a popular PNP bipolar junction transistor that comes in a small TO-92 package. It is a general-purpose PNP transistor that can be used in electronic circuits as a switch or amplifier.

 

In today's blog, we'll gonna show u all about BC557 PNP transistor, its pinout, parameter, how does it work, where to use it and so on, hope this blog helps!

TOP3 Electronic Project Using BC557


Catalog

BC557 Description

BC557 Pinout

BC557 Features

BC557 Parameter

BC557 Equivalent

BC557 Working Principle

Where & How to use BC557

How to safely long run BC557 in a circuit

BC557 Typical Application

BC557 Package

BC557 Application

BC557 Manufacturer

Component Datasheet

FAQ


BC557 Description

BC557 is a popular PNP bipolar junction transistor that comes in a small TO-92 package. It is a general-purpose PNP transistor that can be used in electronic circuits as a switch or amplifier. Its HFE ratings range from 125 to 800, making it an ideal transistor for use as a small signal amplifier in electronic circuits such as audio signal amplification.

 

The HFE ratings of BC557 can be determined by the last letter after its number, for example, BC557A HFE ratings range from 110-220, BC557B HFE ratings range from 200-450, and BC557C HFE ratings range from 420-800. The maximum collector dissipation is 500 milliwatt, which is another advantage for using it in amplification stages.

 

Furthermore, it will perform well when used as a switch for loads less than 100mA. The transistor also has a good collector to emitter (VCE) value of -45V, so it can be used in circuits requiring 40 to 45 volts DC.


BC557 Pinout

BC557 transistor BC557 transistor pinout
BC557 transistor BC557 transistor pinout

 

Pin Number Pin Name Description
1 Collector Current flows in through collector
2 Base Controls the biasing of transistor
3 Emitter Current Drains out through emitter

BC557 Features

  • Bi-Polar PNP Transistor

  • DC Current Gain (hFE) is 300 maximum

  • Continuous Collector current (IC) is 100mA

  • Emitter Base Voltage (VBE) is 6V

  • Base Current(IB) is 5mA maximum

  • Available in To-92 Package


BC557 Parameter

Package / Case: TO-226-3 TO-92-3 (TO-226AA)
Base Product Number: BC557
Supplier Device Package: TO-92-3
Transistor Type: PNP
Vce Saturation (Max) @ Ib Ic: 650mV @ 5mA 100mA
Current - Collector Cutoff (Max): 15nA (ICBO)
DC Current Gain (hFE) (Min) @ Ic Vce: 110 @ 2mA 5V
Current - Collector (Ic) (Max): 100mA
Voltage - Collector Emitter Breakdown (Max): 45V

BC557 Equivalent

  • BC557 PNP equivalent transistor: BC157, BC558, 2N3906, 2SA1943, BD140, S8550, TIP127, TIP42

  • NPN Complementary: NPN Complementary of BC557 is BC547

  • The output pins of some equivalents are different please see pinout details of the equivalent transistor before replacing in the circuit.


BC557 Working Principle

In PNP transistors, holes are the majority carriers, whereas in NPN transistors, electrons are the majority carriers. Although holes are the majority carriers, the base terminal is still important in the overall operation of the transistor.

 

In the NPN case, holes are emitted from the emitter instead of electrons, and they are collectors via the collector terminal.

bc557 structureBC557 Structure

BC557 is known as a current controlled device because the small current present at the base side is used to control the large current present at the remaining terminals.

 

Remember that when the transistor is turned off, there is a current at the base terminal, whereas when the transistor is turned on, there is no current at the base terminal.


Where & How to use BC557

Because the BC557 is a general purpose transistor, it can be used in a wide range of general purpose applications, such as audio amplifiers in small radios, electronic buzzers, electronic bells, and other sound circuits that require low amplification.

 

This transistor can also be used in audio preamplifier stages due to its high gain. Aside from these applications, this transistor can also be used as a switch in electronic applications for a 100mA load, switching any part of an electronic circuit, other high-power transistors, LEDs, relays, and so on.


How to safely long run BC557 in a circuit

To safely run this transistor for good performance for a long time in your electronic circuit, do not operate it at -45V DC, always use a suitable base resistor, do not provide this transistor with more than -100mA load, the operating and storage temperature around the transistor should be between -65 and +150 degrees Celsius, and always check the transistor's pinout before placing it in the circuit.


BC557 Typical Application

1. BC557 Transistor as switch

 

When a transistor is used as a switch, it operates in the Saturation and Cut-Off Regions, as previously explained. As previously stated, a transistor will act as an open switch during forward bias and as a closed switch during reverse bias; this biasing can be accomplished by supplying the necessary amount of current to the base pin. As mentioned, the biasing current should be limited to a maximum of 5mA. Anything more than 5mA will destroy the transistor, so a resistor is always connected in series with the base pin. The resistor (RB) value can be calculated using the formula below:

 

RB  = VBE / IB

 

Where, the value of VBE should be 5V for BC557 and the Base current (IB depends on the Collector current (IC). The value of IB should not exceed mA.

 

2. BC557 Transistor as Amplifier

 

When in the active region, a transistor acts as an amplifier. It has the ability to amplify power, voltage, and current in a variety of configurations.

 

Some of the configurations used in amplifier circuits are:

 

  • Common emitter amplifier

  • Common collector amplifier

  • Common base amplifier

 

The most common and widely used configuration among the aforementioned emitter types is the common emitter type. The DC current gain of a transistor when used as an amplifier can be calculated using the following formula:

 

DC Current Gain = Collector Current (IC) / Base Current (IB)


BC557 Package

BC557 Package


BC557 Application

  • Preamplifier

  • Small signal audio amplifier

  • Driving Loads under 0.1mA or 100mA

  • Any general purpose application that comes under its ratings.


BC557 Manufacturer

ON Semiconductor (Nasdaq: ON) is driving energy efficient innovations, empowering customers to reduce global energy use. The company offers a comprehensive portfolio of energy efficient power and signal management, logic, discrete and custom solutions to help design engineers solve their unique design challenges in automotive, communications, computing, consumer, industrial, LED lighting, medical, military/aerospace and power supply applications. ON Semiconductor operates a responsive, reliable, world-class supply chain and quality program, and a network of manufacturing facilities, sales offices and design centers in key markets throughout North America, Europe, and the Asia Pacific regions.


Component Datasheet

BC557 Transistor Datasheet


FAQ

  • What is BC557 transistor?

BC557 is a widely used PNP bipolar junction transistor manufactured in small TO-92 package. It is a general purpose PNP transistor that can be used as a switch or amplifier in electronic circuits. ... The max collector dissipation is 500 milliwatt which is also an another good point to use it in amplification stages.

  • Can I use BC557 instead of BC547?

The BC547-9 series and BC557-9 series are functionally identical to the common BC107-9 series. All have a maximum power dissipation of 500mW. They have essentially similar specifications and can generally be substituted for one another (within the PNP and NPN groups of three each)

  • What does a transistor do?

A transistor, also known as a BJT (Bipolar Junction Transistor), is a current driven semiconductor device which can be used to control the flow of electric current in which a small amount of current in the Base lead controls a larger current between the Collector and Emitter.

 

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