BC557 PNP Transistor

Description

BC557 Pin Configuration 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 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 Note: Complete Technical Details can be found at the BC557 datasheet given at the end of this page. BC557 Equivalent PNP Transistors BC157, BC558, 2N3906, 2SA1943, BD140, S8550, TIP127, TIP42 Brief Description on BC557 Transistor BC557 is a PNP transistor hence the collector and emitter will be closed (Forward biased) when the base pin is held at ground and will be opened (Reverse biased) when a signal is provided to base pin. This is where a PNP transistor differs from a NPN transistor, a Logic state (blue colour) is used to toggle between Ground and Signal Voltage (Emitter-Base Voltage VBE) as shown below 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.