8550 PNP General Purpose Transistor

Specification	Details
Transistor Type	PNP
Package Type	TO-92 (Plastic Case)
Max Collector Current	500mA to 700mA (Continuous)
Max Collector-Emitter Voltage	25V
Max Collector-Base Voltage ($V_{CBO}$)	40V
Power Dissipation	625mW
DC Current Gain	85 to 300

Price

₹ 4.24

(Tax included)

Barcode: 3781303

Product Description

The 8550 is a high-current, general-purpose PNP epitaxial silicon transistor designed for a wide variety of switching and amplification applications. While many standard small-signal transistors are limited to 100mA, the S8550 can handle a continuous collector current of up to 700mA in some variants, making it exceptionally useful for driving small DC motors, high-power LEDs, and relay coils. Housed in the universal TO-92 plastic package, it is a staple component for hobbyists and engineers alike. It is frequently paired with its NPN counterpart, the S8050, to create efficient Class-B push-pull audio amplifiers or H-bridge motor controllers.

Key Features

High Current Handling: Capable of driving loads up to 500mA–700mA, bridging the gap between small-signal and medium-power transistors.
Low Saturation Voltage: Ensures minimal power loss and heat generation when the transistor is used as a fully "ON" switch.
High Gain ($h_{FE}$): Provides excellent amplification factor, allowing a very small base current to control a much larger load current.
Complementary Pair: Specifically designed to work in tandem with the S8050 (NPN) for symmetrical circuit designs.
Robust TO-92 Package: The compact, 3-pin through-hole design is easy to solder and fits perfectly into standard breadboards and stripboards.

Technical Details

Frequency : 100 MHz to 120 MHz.
Storage Temperature: -65°C to +150°C.
Pin Configuration: 1-Emitter, 2-Base, 3-Collector (Standard for S8550).

Prototyping and Engineering Tips from Robogears

PNP Logic Check: CRITICAL: As a PNP transistor, the 8550 is "active low." This means the load is typically connected between the Collector and Ground, and the Emitter is connected to VCC. The transistor turns ON when the Base voltage is lower than the Emitter voltage (usually by 0.7V).
The Base Resistor: Never connect the Base of the 8550 directly to a microcontroller pin (like Arduino or ESP32). Without a current-limiting resistor (typically 1k to 10k ohms), the transistor will draw too much current from the MCU pin, potentially destroying both the chip and the transistor.
Heat Dissipation: If you are running the 8550 near its limit (e.g., driving a 500mA motor), the TO-92 package will get quite hot. Ensure there is adequate spacing between components for airflow. If it becomes too hot to touch, you may need to parallel two transistors or switch to a larger TO-126 or TO-220 package (like the BD140).
Flyback Diode Requirement: When using this transistor to switch inductive loads like Relays or Solenoids, always place a 1N4007 diode in reverse across the load. This prevents the "Inductive Kickback" voltage spike from frying the transistor when it turns off.
Identifying Pinouts: Always check the specific datasheet for your brand of 8550. While most follow the E-B-C layout, some variations may have different pin orders. Use a multimeter's "Diode Test" or a basic component tester to verify the Emitter and Collector before soldering.

Package Includes

1 x 8550 PNP General Purpose Transistor (TO-92)

Disclaimer: Do not exceed the maximum Collector-Emitter voltage of 25V. Always verify the current requirements of your load before connection. Static electricity can damage semiconductor junctions; handle with care and avoid touching the pins directly if possible. Ensure proper orientation to avoid short circuits.