The BC557 transistor is a PNP bipolar junction general-purpose transistor used as a switch or amplifier in electronic circuits. It has 125 to 800 HFE ratings, which make it an ideal transistor to use as a small signal amplifier in electronic circuits. The maximum collector dissipation is 500 milliwatts, another good feature of this transistor. Moreover, it performs well when used as a switch for loads under 100 mA. The BC557 transistor also has a good collector-to-emitter (VCE) value that is -45V; therefore, you can easily use it in circuits using 40 to 45 volts DC.
Besides these uses, BC557 is also a good general-purpose PNP transistor to use in your simple electronics projects, so this transistor has to be in your electronics lab.
Features of BC557 Transistor
- 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
PNP Complementary of BC557 Transistor:
BC557 is an NPN transistor so its complement is BC547
Replacement and Equivalent:
The alternatives to this transistor are 2N3906, 2N4403, BC556, and BC327. Keep in mind that the output pins of some equivalents are different. So please see the pinout details of the equivalent transistor before replacing it in the circuit.
Applications of BC557 Transistor:
- BC557 is used in the preamplifier
- It is also used in small signal audio amplifiers.
- It is also used in Driving Loads under 0.1 mA or 100 mA.
- This transistor is a widely used PNP transistor so it can be used in any general-purpose application that comes under its ratings
How to protect transistor BC557:
For the long life of this transistor, it is essential to not operate it under -45V DC in your electronic circuits, to always use a suitable resistor on the base point, and to not use this transistor for more than a -100mA load, the operating and storage temperature. The temperature should be under -65 d +150 degrees centigrade, a and always check the pinout of the transistor before placing it in By chance wrongly placed, then check the transistor again before placing it in the circuit because wrong input can weaken its performance.
BC557 as a Switch Circuit:
As we use a transistor as a switch, it is operated in the saturation and cutoff regions. A transistor acts as an open switch during forward bias and a closed switch during reverse bias. The maximum base current should be 5 mA for the BC557 transistor, as mentioned above in the features. More current than 5 mA will kill the transistor. So a resistor is always added in series with the base pin. The value of the resistor can be calculated by using this formula.
RB = VBE / IB
