S8550: Overview,Specifications,Main uses,Features,application fields,working principle and alternative models


S8550 Overview:

The S8550 is a general-purpose PNP bipolar junction transistor (BJT) often used in electronic circuits for amplification or switching purposes. Here is an overview of the S8550 transistor, including its specifications, main uses, features, application fields, working principle, and alternative models:



  • Type: PNP Bipolar Junction Transistor (BJT)
  • Package: SOT-23 or similar
  • Collector-Base Voltage (VCBO): Typically 30V
  • Collector-Emitter Voltage (VCEO): Around 25V
  • Emitter-Base Voltage (VEBO): Approximately 5V
  • Collector Current (IC): Typically 0.5A
  • Power Dissipation (Pd): Varies with operating conditions
  • Transition Frequency (fT): Depending on model, typically in the range of a few hundred megahertz
  • DataSheet

    S8550-D-AP PDF

Main Uses:

  • Amplification: Commonly used in amplifier circuits for audio or signal amplification.
  • Switching: Utilized in electronic switches and low-power control circuits.
  • Voltage Regulation: Can be integrated into voltage regulator circuits.
  • Oscillator Circuits: Employed in certain oscillator configurations.


  • Low Noise: Provides low noise amplification capabilities.
  • Compact Package: Available in compact surface-mount packages like SOT-23.
  • PNP Configuration: Configured as a PNP transistor with specific voltage and current ratings.
  • Medium Power: Suitable for applications requiring moderate power handling.
  • General-Purpose: Versatile transistor suitable for various electronic applications.

Application Fields:

  • Audio Amplifiers: Used in audio amplifier stages for low power audio applications.
  • Signal Processing Circuits: Integrated into signal processing and control circuits.
  • Consumer Electronics: Found in various consumer electronic devices.
  • Automotive Electronics: Applied in automotive systems for control and signal processing.

Working Principle:

  • In an electronic circuit, the S8550 can be used as an amplifier to amplify small signals.
  • In a switching application, the transistor controls the flow of current by acting as a switch.
  • By biasing the transistor correctly, desired functionality like amplification or switching can be achieved.

Alternative Models:

  • S8050: Similar in characteristics to the S8550, but with potentially slightly different specifications.
  • 2N3906: Another commonly used PNP transistor with comparable characteristics.
  • BC557: Comparable PNP transistor that can be used as an alternative.


  • The S8550 is a versatile bipolar junction transistor suitable for a range of electronic applications requiring amplification or switching capabilities.
  • Selection of the appropriate transistor should consider the specific requirements of the circuit and the voltage and current ratings needed.

The S8550 PNP transistor is a general-purpose component with applications in amplification, switching, voltage regulation, and oscillator circuits, offering moderate power handling capabilities and low noise amplification features in a compact package.