TIP3055 Overview

The TIP3055 is a high-power NPN transistor designed for general-purpose power amplification and switching. It can handle up to 15A of collector current, with a maximum collector-emitter voltage of 60V and a power dissipation rating of 90W. Its saturation voltage is typically around 0.7V at 4A, making it efficient in both linear and switching circuits. Housed in a TO-247 package, it offers fast switching performance and is widely used in audio amplifiers, inverters, and motor driver circuits. It’s often paired with its complementary PNP counterpart, the TIP2955.

TIP3055 Pinout

TIP3055 has three pins: When facing the flat side with the pins pointing down, the order from left to right is: Base, Collector, Emitter. The metal tab is internally connected to the collector.

Pin Configurations:

● Pin 1 – Base: Receives the control signal to turn the transistor on or off.

● Pin 2 – Collector: Connects to the load or positive supply voltage.

● Pin 3 – Emitter: Connects to ground or the circuit’s return path.

The metal tab on the back is internally connected to the collector and should be properly heatsinked.

TIP3055 CAD Models

TIP3055 and TIP2955 Push-Pull Audio Amplifier Circuit

TIP2955 and TIP3055 are commonly used together in high-power audio amplifier circuits. As a complementary PNP-NPN pair, they form the output stage in a typical 70W OCL (Output Capacitor-Less) amplifier. This design is capable of driving 4–8Ω speakers using symmetrical ±25V to ±35V power rails.

How the Circuit Works

The push-pull configuration splits the audio signal:

• TIP3055 (NPN) handles the positive half of the waveform.

• TIP2955 (PNP) handles the negative half.

Small-signal transistors like 2N3904 and 2N3906 act as drivers, supplying base current to switch the power transistors fully. Emitter resistors (~0.27Ω) ensure current sharing and thermal stability. A diode-based bias circuit sets the idle current, minimizing crossover distortion. Feedback capacitors maintain high-frequency stability and prevent oscillation.

Since this is an OCL design, there's no output capacitor. That improves low-frequency response, but DC offset must be carefully managed to protect the speaker.

Key Considerations

• Use adequate heat sinks for both TIP3055 and TIP2955.

• Maintain symmetrical power rails to avoid distortion or DC offset.

• Properly design the bias network for thermal tracking and stability.

Conclusion

The TIP3055 and TIP2955 transistor pair provides robust performance and versatility, particularly popular in audio amplifiers and power supply designs. Correct implementation of heat dissipation and biasing ensures reliable, high-quality output for various practical applications.