BD708 Technical Summary

Overview

The BD707, BD709, and BD711 are silicon epitaxial-base NPN power transistors housed in a Jedec TO-220 plastic package. These transistors are designed for high-power applications requiring robust performance and thermal stability. The BD708 series is optimized for use in power amplification, switching, and linear regulation circuits, offering excellent current handling capabilities and low saturation voltage.

These transistors are fabricated using advanced epitaxial-base technology, ensuring high reliability and consistent performance under demanding conditions. The TO-220 package provides efficient thermal dissipation, making them suitable for applications where heat management is critical.

Features

• High Current Capability: Designed to handle collector currents up to 8A, making them ideal for power applications.
• Low Saturation Voltage: Ensures minimal power loss during operation, improving overall efficiency.
• High Voltage Tolerance: Collector-emitter voltage (V_CEO) ratings up to 100V, suitable for medium to high-voltage circuits.
• Robust Thermal Performance: TO-220 package with a thermal resistance of 62.5°C/W (junction-to-case), enabling effective heat dissipation.
• Wide Operating Temperature Range: Operates reliably from -55°C to +150°C, ensuring performance in extreme environments.
• Complementary PNP Options: Available with complementary PNP transistors (e.g., BD708/BD710) for push-pull configurations.

Applications

The BD708 series transistors are versatile components suitable for a wide range of applications, including:

• Power Amplifiers: Used in audio and RF amplification stages due to their high current and voltage handling capabilities.
• Switching Regulators: Ideal for DC-DC converters and power supply switching circuits.
• Motor Control: Employed in H-bridge and other motor driver configurations for industrial and automotive systems.
• Linear Voltage Regulators: Suitable for pass transistor applications in adjustable voltage regulators.
• General-Purpose Switching: Used in relay drivers, solenoid controls, and other high-current switching applications.

Electrical Characteristics

The following table summarizes the key electrical specifications of the BD708 series transistors under standard test conditions (T_A = 25°C unless otherwise noted):

Absolute Maximum Ratings

• Collector-Emitter Voltage (V_CEO): 100V
• Collector-Base Voltage (V_CBO): 120V
• Emitter-Base Voltage (V_EBO): 5V
• Collector Current (I_C): 8A (continuous)
• Base Current (I_B): 4A (peak)
• Total Power Dissipation (P_tot): 40W (at T_C = 25°C)
• Operating Junction Temperature (T_j): -55°C to +150°C
• Storage Temperature (T_stg): -55°C to +150°C

Electrical Parameters

• DC Current Gain (h_FE): 40 to 320 (at I_C = 2A, V_CE = 2V)
• Collector-Emitter Saturation Voltage (V_CE(sat)): 0.5V (max) at I_C = 4A, I_B = 0.4A
• Base-Emitter Saturation Voltage (V_BE(sat)): 1.2V (max) at I_C = 4A, I_B = 0.4A
• Transition Frequency (f_T): 3MHz (typical) at I_C = 1A, V_CE = 10V
• Output Capacitance (C_obo): 100pF (typical) at V_CB = 10V, f = 1MHz

Package Information

The BD708 series transistors are housed in a TO-220 package, which is widely used for power devices due to its excellent thermal and mechanical properties. Below are the key package details:

TO-220 Package Dimensions

• Package Type: TO-220AB (Jedec compliant)
• Mounting Style: Through-hole
• Lead Material: Copper alloy
• Weight: Approximately 2.0g
• Thermal Resistance (R_thj-c): 3.125°C/W (max)
• Pin Configuration:
  • Pin 1: Base (B)
  • Pin 2: Collector (C)
  • Pin 3: Emitter (E)

Mechanical Drawing

The TO-220 package features a compact design with a metal tab for heat sinking. The recommended PCB layout includes adequate clearance for the tab and mounting hardware to ensure proper thermal management. The package dimensions are as follows:

• Total Height: 16.0mm (max)
• Lead Length: 14.0mm (min)
• Lead Spacing: 2.54mm (between pins)
• Tab Width: 10.0mm (typical)

Reliability and Compliance

The BD708 series transistors are manufactured under strict quality control processes to ensure long-term reliability. They comply with industry standards, including:

• RoHS compliance (Restriction of Hazardous Substances)
• UL certification (where applicable)
• MSL (Moisture Sensitivity Level) 1, suitable for standard reflow soldering processes

Conclusion

The BD708 series NPN power transistors offer a robust solution for high-current and high-voltage applications. With their low saturation voltage, high current gain, and efficient thermal performance, they are well-suited for power amplification, switching, and regulation tasks. The TO-220 package ensures ease of mounting and effective heat dissipation, making them a reliable choice for demanding electronic designs.