BD708 Pinout, Equivalent, Applications, Datasheet

The BD708 is a PNP silicon power transistor designed for high-current and medium-voltage applications. With a collector current of 12A and a collector-emitter voltage of 60V, it provides excellent performance in power amplifiers, motor control systems, and switching regulators. Packaged in a TO-220 case, it is the perfect complementary match to the BD707 NPN transistor with the same BD708 pinout, forming an efficient push-pull pair for high-fidelity audio and power stages.

bd708 datasheet pinout — BD708 Transistor Datasheet and Specs

Introduction to BD708 PNP Transistor

The BD708 belongs to the BD700 series of silicon power transistors optimized for reliable operation in demanding environments. As a PNP power transistor, the BD708 is widely used in applications requiring high current gain and stable performance at voltages up to 60V.

It is designed for medium to high-power amplification, switching, and control systems. The transistor’s silicon construction ensures durability, while its TO-220 package allows efficient heat dissipation, even under continuous load.

When paired with its complementary BD707 NPN transistor, BD708 delivers balanced and distortion-free output in push-pull amplifier designs. These characteristics make it a dependable choice for engineers working on power amplifier, inverter, and driver circuit projects.

BD708 PNP Transistor

bd708 transistor pin configuration diagram pinout — BD708 Transistor Front View

Pinout of BD708

bd708 transistor pin configuration pinout diagram — BD708 Transistor Pin Configuration Pinout Diagram

Understanding the BD708 Pinout Configuration

The BD708 transistor uses the TO-220 package, a standard format that offers strong mechanical stability and effective thermal performance. Each lead corresponds to a specific transistor terminal used in biasing and current flow control.

Pin Configuration of BD708 Pinout

Pin#	Pin Name	Pin Description
1	Base	Controls transistor conduction
2	Collector	Current enters the transistor
3	Emitter	Current exits the transistor

BD708 Pin Configuration

Pin Orientation:
When viewing the flat side of the transistor with leads facing downward, the order from left to right is Base – Collector – Emitter.

Key Features of BD708 Transistor

PNP silicon power transistor
Collector-emitter voltage up to 60V
Collector current rated at 12A
Maximum power dissipation up to 75W
High DC current gain with stable output
Low collector-emitter saturation voltage
TO-220 package for excellent heat dissipation
Complementary to BD707 NPN transistor
Reliable switching and amplification performance

BD708 Transistor Datasheet and Specifications

Collector-Emitter Voltage (VCEO): 60V
Collector-Base Voltage (VCBO): 60V
Emitter-Base Voltage (VEBO): 5V
Collector Current (IC): 12A
Power Dissipation (PC): 75W (at Tc = 25°C)
DC Current Gain (hFE): 40 (min at IC = 0.5A)
Collector-Emitter Saturation Voltage (VCEsat): Max 1.0V at 4A
Transition Frequency (fT): 3 MHz (typical)
Junction Temperature (Tj): 150°C (maximum)
Thermal Resistance (RθJC): 1.67°C/W

These ratings confirm that the BD708 is a robust transistor suitable for various power circuits and high-efficiency amplifier designs.

Working Principle of BD708 Transistor

The BD708 PNP transistor works by allowing current to flow from its emitter to collector when a small current is applied to the base in the opposite direction of NPN operation. When the base is made slightly negative with respect to the emitter, the transistor conducts and enables current amplification.

This behavior makes BD708 ideal for amplifier output stages, switching circuits, and motor driver control systems. It efficiently handles high collector currents while maintaining low saturation voltage and thermal stability, ensuring consistent operation even under stress.

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Typical Applications of BD708

Power and audio amplifier output stages
DC motor control circuits
Switching power supplies and voltage regulators
Relay and solenoid drivers
Inverter and converter circuits
Complementary push-pull amplifier configurations
Industrial automation and power control systems

NPN Complementary Transistor

The complementary transistor for BD708 is the BD707, an NPN power transistor that shares the same electrical ratings and mechanical configuration.

When BD708 (PNP) and BD707 (NPN) are used together in push-pull configurations, they create balanced output stages ideal for power amplifiers, providing linear current flow and minimal crossover distortion. This complementary pair is widely used in audio power amplifiers, motor controllers, and switch-mode power supplies.

Equivalent Transistors and Alternatives

When selecting a replacement transistor for BD708, ensure that the voltage, current, and power dissipation ratings match closely. Pin configuration compatibility is also crucial to prevent incorrect circuit connections.

Comparison BD708 vs BD707 Complementary Transistors

The BD708 (PNP) and BD707 (NPN) transistors form a complementary pair optimized for push-pull power stages. Both transistors have identical voltage and current ratings — 60V collector-emitter voltage and 12A collector current — but opposite polarity operation.

While the BD707 handles positive current flow, the BD708 conducts during negative cycles, ensuring smooth alternating current amplification. Together, they enhance circuit efficiency and deliver symmetrical waveform reproduction in amplifier outputs and power drivers.

This complementary design makes the BD707-BD708 pair a standard choice in high-quality amplifier and control circuits.

Frequently Asked Questions (FAQ)

What is the BD708 transistor used for?

The BD708 transistor is mainly used in amplifier output stages, motor control circuits, and power regulation systems.

What type of transistor is BD708?

It is a PNP silicon power transistor designed for medium to high-power switching and amplification.

What is the BD708 pin configuration?

Pin 1 is Base, Pin 2 is Collector, and Pin 3 is Emitter.

What is the complementary transistor for BD708?

The complementary NPN transistor for BD708 is the BD707.

Can I use BD706 instead of BD708?

Yes, BD706 can be used as an alternative if voltage, current, and package configuration requirements are compatible with your circuit.

Conclusion

The BD708 PNP transistor is a high-performance power device suitable for a wide range of amplification, switching, and motor driver applications. Its 60V collector-emitter voltage and 12A collector current make it a versatile component for industrial and consumer-grade electronics.

With a sturdy TO-220 package, strong heat dissipation, and low saturation voltage, BD708 offers long-lasting reliability in power circuits. When used alongside the BD707 NPN transistor, it forms a powerful complementary pair capable of delivering high efficiency, minimal distortion, and excellent stability in demanding environments.

Datasheet & Pinout of BD708 NPN Transistor

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Download Datasheet

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