BC257 Transistor Pinout, Applications, Equivalents, Features, and Other Info

Today we are going to discuss the BC257 transistor pinout, applications, equivalents, features, and other information about this device.

 

Absolute Maximum Ratings:

• Package Type: TO-92
• Transistor Type: PNP
• Max Collector Current(I_C): -100mA
• Max Collector-Emitter Voltage (V_CE): -45V
• Max Collector-Base Voltage (V_CB): -50V
• Max Emitter-Base Voltage (VEBO): -6V
• Total Device Dissipation (Pc): 300 miliWatt
• Max Transition Frequency (fT): 180 MHz
• Minimum & Maximum DC Current Gain (h_FE): 110 – 800
• Max Storage & Operating temperature Should Be: -55 to +150 Centigrade

 

Replacement and Equivalent:

BC547, BC546, BC548, C945, BC550, 2SA1528, BC182, 2SA1526, 2SA1524

 

BC257 Transistor Explained / Description:

BC257 is a TO-92 package bipolar junction transistor designed to be used in direct coupled circuits, small audio amplifiers and other general purpose applications. The transistor has many good features such as DC current gain of 110 to 800 which makes it suitable in circuits that requires to increase the gain of a signal, noise figure of 2 to 4dB makes it a good low noise transistor ideal to use in circuits that requires to increase the gain of a signal but also with low noise. Another good features is the transition frequency of 180MHz also makes it suitable for RF circuits under this frequency such as FM band.

Understanding the absolute maximum ratings of the transistor, the max collector current is 100mA means it can drive load of upto 100mA, max collector-emitter voltage is -45V which means it can drive load of upto -45V, man collector-base voltage of the transistor is -50V, collector-base voltage helps maintain transistor’s performance, the max emitter-base voltage is -6V, this voltage make the transistor stable.

All the above features and max ratings of the transistor makes it a good candidate to use it in wide variety of applications.

 

How to Use this Transistor:

It is a BJT (Bipolar Junction Transistor) so the using procedure is same as you use any other BJT transistor for switching and amplification purposes. In short applying signals to the base pin, connecting emitter pin with the positive rail and getting output from the collector in amplifier circuit or driving load with the collector in switching circuits.

 

Applications:

Audio Amplifier Circuits

Audio Preamplifier Circuits

Switching Circuits

Audio Amplifier Stages

Darlington Pairs

Automotive Circuits

Battery Charger Circuits

Tx and Rx Circuits

Solar Circuits

 

Safe Operating Guidelines:

Here are some guidelines for safe operation of the transistor.

• Always use 20% below from its absolute maximum ratings.
• The maximum collector-emitter voltage is -45V but by following the above 20% guidelines we will not drive load of more than -36V.
• Same will be applied in collector current the maximum collector current is 100mA but we will not drive load of more than 80mA.
• Always check the pin layout before using it in the circuit.
• The storage and operating temperature should be between -55°C to 150°C.

 

Datasheet:

To download the datasheet just copy and paste the below link in your browser.

https://www.alldatasheet.com/datasheet-pdf/view/75188/MICRO-ELECTRONICS/BC257.html