BC557 Transistor

BC557 Transistor

BC557 transistor is a general-purpose transistor, used like an amplifier or a switch in electronic circuits. Its hFE ratings of this transistor range from 125 to 800 to make the transistor ideal by using like an amplifier within electronic circuits like audio signal amplification.

• PNP-Type
• Max voltages Collector-Emitter: -45 V
• Maximum Collector-Base Voltage: -50 V
• Max Emitter-Base Voltage: -5 V
• Collector Current: -0.1 A
• Collector Dissipation – 0.5 W
• Current Gain (hfe) – 110 to 800
• Frequency of BC557  – 150 MHz
• 2 dB Noise Figures
• Operating Temperature Range -65 to +150 °C
• TO-92 Package

BC557 Pin Configuration

BC557 has a gain value of 110 to 800, this value determines the amplification capacity of the transistor. The maximum amount of current that could flow through the Collector pin is 100mA, hence we cannot connect loads that consume more than 100mA using this transistor. To bias a transistor, we have to supply current to base pin, this current (IB) should be limited to 5mA.

When this 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 and the typical voltage allowed across the Collector-Emitter (V­CE) or Base-Emitter (VBE) could be 200 and 900 mV respectively.

When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region and the Base Emitter voltage could be around 660 mV. BC557 Transistor as switch When a transistor is used as a switch it is operated in the Saturation and Cut-Off Region as explained above. As discussed a transistor will act as an Open switch during Forward Bias and as a Closed switch during Reverse Bias, this biasing can be achieved by supplying the required amount of current to the base pin.

As mentioned the biasing current should maximum of 5mA. Anything more than 5mA will kill the Transistor; hence a resistor is always added in series with base pin. The value of this resistor (RB) can be calculated using below formulae. 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. BC557 Transistor as Amplifier A Transistor acts as an Amplifier when operating in Active Region. It can amplify power, voltage and current at different configurations.

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Also do not forget to check out our other transistors in the Transistors section.

What is difference between BC547 and BC557?

BC557 is a PNP transistor, nevertheless, BC547 is an NPN transistor.

BC557 Transistor – check out the best price in Bangladesh