BC547 transistor Pinout, Specs, Datasheet, Equivalent and Uses

BC547 transistor pinout or pin diagram has three pins, starting from left: collector, emitter, and base respectively. It is available in two packages: SMD and TO-92 package.

A transistor is a semiconductor device used for amplifying or switching an electronic signal.

BC547 is an NPN Bipolar Junction Transistor. And like all other transistors, BC547 has three pins called the emitter, collector, and base respectively.

BC547 transistor acts as a switch between the collector and emitter. If the base of the transistor is given enough current, this switch closes and the current flows from the collector to the emitter.

So a small current to the base pin of the transistor switches the large current between the collector and the emitter.

BC547 is also used for the amplification of the input signals. A small amount of current at the base is used to control a large amount of current between the collector and emitter. So basic applications of BC547 are switching and amplification.

Pinout of BC547: Pin diagram

The BC547 transistor pinout shows 3 pins from left: Collector, base, and emitter respectively.

BC547 transistor Pinouts
BC547 transistor Pinouts
Pin NumberPin NameDescription
1CollectorThis pin act as an inlet as the current enters the transistor from here. The collector is denoted by ‘C’.
2BaseThis pin controls the transistor biasing. The base is denoted by ‘B’.
3EmitterThis pin act as an outlet and the current comes out of the transistor from here. The emitter is denoted by ‘ E’.

 

BC547 Datasheet:

BC547 comes in two packages SMD package and the TO-92 package.

Click this link to view the entire DATASHEET of BC547

You can find detailed information on BC547 in the datasheet given above. Specifications and characteristics like Absolute maximum ratings, Block diagram, biasing methods, and package dimensions can be found in the datasheet.

Technical specifications of BC547:

  • Package-Type: TO-92
  • Transistor Type: NPN
  • Max Collector Current (IC): 100mA
  • Max Collector-Emitter Voltage (VCE): 45V
  • Max Collector-Base Voltage (VCB): 50V
  • Max Emitter-Base Voltage (VEBO): 6V
  • Max Collector Dissipation (Pc): 500 milliwatt
  • Max Transition Frequency (fT): 300 MHz
  • Minimum & Maximum DC Current Gain (hFE): 110 – 800
  • Max Storage & Operating temperature Should Be: -65 to +150 Centigrade
  • Low Noise: 2-10 dB

BC547 transistor Uses and Applications:

  • The highest transition frequency of BC547 is 300MHz. Thus, it can also be used in RF circuits.
  • Amplification of current
  • Audio Amplifiers
  • Switching Loads < 100mA
  • Transistor Darlington Pairs
  • Amplifiers like Audio, signal, etc.
  • Darlington pair
  • Quick switching
  • PWM (Pulse Width Modulation)

BC547 Transistor Equivalent

BC547 transistor can be used as an alternative to many transistors:

BC548, BC549, BC636, BC639, 2N2222 TO-92, 2N2222 TO-18, 2N2369, 2N3055 and 2N3904 all are BC547 transistor equivalent.

BC547 TO-92 Package Dimensions

BC547 transistor package dimensions
BC547 transistor package dimensions

BC547 Transistor Projects

BC547 transistor can be used to create many cool projects. Some of the beginner transistor projects using B547 are listed below:

Not Gate using a Transistor on Breadboard

NOR Gate using a Transistor on Breadboard

Rain Sensor Alarm using two BC547 Transistor

Working States OR Modes of Operation of BC547:

Like every other transistor BC547 transistor works in three regions:

  • Active Region.
  • Saturation Region.
  • Cut off Region
Modes of operation of BC547
Modes of operation of BC547

(a) Active region

The active region lies between the cut-off and saturation regions. In the active region, the transistor emitter junction is forward biased and the collector junction is reverse biased. In the active region, the collector current is β times the base current, i.e.,

IC=β IB

here, IC = collector current

Β = current amplification factor

IB = base current

So the collector current increases in proportional to the base current.

(b) Saturation region

In this region, transistor works like a short circuit. The collector and Emitter currents are maximum in this region. In the saturation region, both the emitter and collector junctions are forward biased. In other words, the transistor operates as a closed switch or short circuit carrying maximum current which implies:

IC=IE

here IC = collector current and IE = emitter current.

(c) Cut-off region

In this region, transistor works as an open switch or open circuit. The collector, emitter, and base currents are all zero in this region. In the cut-off region, both the emitter and collector junctions are reverse biased. As in the cut-off region, the collector, emitter, and base current are zero, which gives

IC=IE=IB=0

here IC = collector current, IE = emitter current, and IB = base current.

BC547 TRANSISTOR AS A SWITCH

The region responsible for a transistor to work as a switch are Saturation Region and the Cut-off Region. When we apply high enough current at the base of the transistor, it makes a path for the collector current to go through the base towards the emitter.

In order to use the transistor as a switch, it must be driven into the saturation region with enough base current. And a transistor operates as a closed switch under the saturation region.

Transistor as a closed switch
Transistor as a closed switch

As soon as a positive signal (in form of voltage and current) is removed across the base of the transistor, the flow of electric current between the collector and emitter becomes zero. And the transistor behaves like an open switch under the cut-off region.

Transistor as an open switch
Transistor as an open switch

This simply implies if we apply signal (voltage/current) across the collector and emitter but not across the base, the transistor will not work. But a small signal across the base is enough to make it work.

BC547 TRANSISTOR AS AN AMPLIFIER

A transistor acts as an amplifier by increasing the strength of a weak signal applied at its base. Transistors work as an amplifier in the active region or linear region. The figure given below shows how to use a transistor as an emitter amplifier.

 BC547 Transistor as an amplifier
BC547 Transistor as an amplifier

**Image Source: instrumentationtools

In this region, with the increase in the base current, the collector current also increases proportionally according to the formula:

IC=β IB

Here, IC = collector current

Β = current amplification factor

IB = base current

Thus, a small input signal results in a large output, which implies that the transistor works as an amplifier.

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