BC557 Transistor Pinout Equivalent Uses& Feature

BC557 is a PNP transistor so the collector and emitter will be off (Forward biased) when the base pin is put at ground and will be on when a signal is provided to base pin. The amplification capacity of this transistor is 110-800. The maximum amount of current that could flow through the collector pin is 100mA, So its mean that load which consume more than 100mA can not be connected with this transistor.

When BC557 transistor is fully biased then it can allow a maximum of 100mA to flow across the collector and emitter. This stage is called Saturation Region. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region.

Pin Configuration of BC557 Transistor

Pin Configuration of BC557

Features / Technical Specifications:

  • Type of Transistor: PNP
  • Maximum Collector Current(IC): -100mA
  • Max Collector & Emitter Voltage (VCE): -45V
  • Max Collector & Base Voltage (VCB): -50V
  • Max Emitter to Base Voltage (VBE): -5V
  • Maximum Collector Dissipation (Pc): 500 Milliwatt
  • Transition Frequency max (fT): 100 MHz
  • Minimum and  Maximum DC Current Gain (hFE): 125 to 800
  • Storage and Operating temperature Should be: -65 to +150Centigrad
  • Package Type: TO-92

Where We Can Use BC557 NPN transistor

The BC557 is a general purpose widely used transistor therefore it is can  be used in variety of application such as audio amplifier, electronics buzzers, electronics bells, switching and sound circuits. It has very good gain of this transistor that is way it can also be used in audio preamplifier stages. Beside these uses BC557 can also use in switching application for 100mA load, it can be used to switch any part of an electronic circuit.

Alternate of BC557 transistor

BC556, 2N3906, 2N4403, BC327 can be used as alternate of BC557 but pin configuration can be different so please must check the pins before use any alternate.

Compliment Of BC557 Transistor

The NPN compliment of this transistor are BC547, BC548, 3904, 2n2222 etc.


  • Uses in Preamplifier
  • It can be use in small signal audio amplifier
  • Used in driving loads under 0.1mA or 100mA
  • Any general purpose application.

Safety of BC557 Transistor:

For the long life of this transistor in your electronic circuit this transistor is essential to not operate under -45V DC, this transistor does not provide more than-100mA load, always use suitable base resistor. The transistor around the operating and storage temperature should be under -65 to +150 Centigrade, and must be check the pinout of the transistor before use of  any transistor.

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