BD678 Transistor Pinout, Equivalent, Applications, Features and Specs

If you are looking for BD678 and BD678A transistors details such as their pinout, equivalent, applications, features and specs then you have some to the right page. This post contains all the important information about this transistor.


 BD678 Transistor Pinout, Equivalent, Applications, Features and Specs



Absolute Maximum Ratings:

  • Package Type: TO-126
  • Transistor Type: PNP Darlington
  • Max Collector Current(IC): 4A
  • Max Collector-Emitter Voltage (VCEO): 60V
  • Max Collector-Base Voltage (VCBO): 60V
  • Max Emitter-Base Voltage (VEBO): 5V
  • Max Collector Power Dissipation (Pc): 40 Watt
  • Minimum DC Current Gain (hFE): 750
  • Max Storage & Operating temperature: -65 to +150 Centigrade


PNP Complementary:

PNP Complementary of BD678 is BD677


Replacement and Equivalent:

NTE2346, MJE702, MJE700, MJE1092, MJE1090, KSE702, KSE700, BD702, BD682, BD680, BD338, BD334.


BD678 Transistor Explained / Description:

BD678 is a PNP Darlington transistor available in TO-126 package. A Darlington transistor contains two transistors inside a single transistor package. These two transistors are connected in such a way that increases the gain of the transistor.

BD678 is designed to use in switching and medium power linear / audio amplifier applications. It is the transistor of the BD6XX series which also contains other transistors such as BD676, BD680, and BD682. All the transistors are slightly different from each other but can easily be used in place of each other if you are using them in voltage below 45V.

Looking at the absolute maximum ratings of the transistor the max collector current is 4A, max collector-base voltage 60V, Max collector-emitter voltage is also 60V, and max DC current gain is 750.


Where We Can Use it & How to Use:

BD678 can be used to control motors, can drive different types of loads, and amplify electronic signals. Using procedure of this transistor is same as we use any other darlington transistor by connecting its base to the output signal, its collector with the positive supply of the load and the load negative supply will be connected with the negative rail of the circuit.



Pulse Generator

Motor Control

LED Drivers

Voltage Regulation

Audio Amplifiers

Battery Operated Applications

Voltage inverters

Switching Circuits

DC to DC Converters


Safe Operating Guidelines:

For long-term performance, it is important to follow these safety guidelines.

  • Do not use the transistor to its absolute maximum ratings and always stay 20% below from its max ratings.
  • So the maximum collector current is 4A therefore to not drive load of more than 3.6A.
  • The max collector-emitter voltage is 60V so do not drive load of more than 48V.
  • The temperature around the transistor should be maintained between -65°C to 150°C.



To download the datasheet just copy and paste the below link in your browser.

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