PNP Transistor BC 558

🛠️ PNP Transistor – BC558 (TO‑92 Package)

Overview

The BC558 is a widely used PNP silicon transistor ideal for switching and amplification in low-power electronic circuits. It's the PNP complement to the BC548 NPN transistor and is popular in general-purpose applications.

Key Features

• Collector current: up to 100 mA

• Collector–Emitter voltage (Vₙₑₒ): 30 V

• Collector–Base voltage (Vₙₑₒ): 30 V

• Power dissipation: 500 mW

• DC current gain (hₙE): 110–800 depending on variant (A/B/C)

• Transition frequency (fₜ): approx. 150 MHz

• Complement to BC546/547/548 NPN series

• Standard TO‑92 plastic package

Pinout

With the flat face facing you and leads downward:

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1 = Collector (left)
2 = Base      (middle)
3 = Emitter   (right)

Typical Arduino Wiring (High-Side PNP Switch)

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Emitter → +V supply  
Collector → Load → GND  
Base → Arduino digital pin via 1 kΩ resistor

• Pulling the base LOW turns the transistor ON

• Include a flyback diode for inductive loads

• Ensure a shared ground between circuits
  

Applications

• Driving small loads (LEDs, relays, sensors) from positive rails

• PNP stage in push-pull amplifiers paired with BC548

• Audio preamplifiers and buffering

• Part of oscillator or timing circuits

• General-purpose switching under 100 mA

✅ Resources

1. 📄 Datasheet: ON Semiconductor BC556/557/558 PNP Transistors – full specs and ratings watelectronics.comelectronica-pt.com+3alltransistors.com+3datasheet4u.com+3

2.