BD243/A/B/C Transistor Pinout, Equivalents, Applications, Explanation And More

BD243 is an NPN power transistor; this post describes pinout, equivalents, applications, explanation and other details of BD243, BD234A, BD243B and BD243C transistors.


BD243 A/B/C Transistor Pinout, Equivalents, Applications, Explanation



Features / Technical Specifications:

  • Package Type: TO-126
  • Transistor Type: NPN
  • Max Collector Current(IC): 6A
  • Max Peak Collector Current: 10A
  • Max Collector-Emitter Voltage (VCE): BD243=45V, BD243A=60V, BD243B=80, BD243C=100
  • Max Collector-Base Voltage (VCB): BD243=45V, BD243A=60V, BD243B=80, BD243C=100
  • Max Emitter-Base Voltage (VEBO): 5V
  • Max Collector Dissipation (Pc): 65 Watt
  • Minimum DC Current Gain (hFE): 15 TO 30
  • Max Storage & Operating temperature: -65 to +150 Centigrade


PNP Complementary:

PNP Complementary of BD243/A/B/C is BD244/A/B/C


Replacement and Equivalent:

Replacement for BD243A:


Replacement for BD243, BD243A, BD243B:

2N5497, 2N6121, 2N6123, 2N6288, 2N6289, 2N6290, 2N6291, 2N6292, 2N6293, 2SC1107, 2SC1109, 2SD476, 2SD1412, BD291, BD293, BD295, RCA1C10, RCA1C14


Replacement for BD243C:

2SC1108, 2SC1110,


BD243 A/B/C Transistor Explained / Description:

BD243 and other transistor in this series such as BD243A, BD243B and BD243C are NPN power transistors available in TO-220 package. These transistors are designed for general purpose switching and amplification purposes. The collector current of all these transistors is 6A but the maximum collector to emitter voltage is different in all, collector to base voltage for BD243 is 45V, BD243A is 60V, BD243B is 80V and BD243C is 100V. Although if you are using it in a design in which you are driving load under 45V then you can use any transistor from BD243/A/B/C. But if you are driving load above 45V then you can use BD243B which is able to drive upto 80V and if you load require more than 80V then you can use BD243C.

The maximum emitter to base voltage is 5V, maximum power dissipation is 65 Watts and minimum DC current gain is 15 to 30.


Where We Can Use it & How to Use:

BD243/A/B/C are general purpose transistors and can be used for wide variety of purposes in electronic circuits. When used as a switch the transistor is capable to drive load of up to 6A which is enough to drive variety of motors, electronic switches, relays, high power transistors etc. On the other hand it can also be used for audio amplification purposes and can be used to make high power audio amplifiers.



Driving or Switching Loads under 6A

High Power Audio Amplifier Circuits

BMS Applications

Motor Drivers

Battery Chargers


Safe Operating Guidelines / Absolute Maximum Ratings:

Follow these guidelines to safely operate this transistor and get long life performance with this component:

  • Do not use the transistor to its absolute maximum ratings and always stay 20% below from its max ratings.
  • The maximum collector current or maximum continuous collector current of all the transistors is 6A therefore do not drive load of more than 4.8A.
  • The maximum collector to emitter voltage is of all the transistors is different so if you are using BD243 then do not drive load of more than 36V, if you are using BD243A then the maximum load can be under 48V, for BD243A the maximum load you can drive is 64V and if you are using BD243C then the maximum load you can drive for safety and stable performance can be 80V.
  • Always use a suitable heatsink with the transistor and also isolate the heatsink from rest of the circuit because the collector of the transistor is also connected with the heatsink tab.
  • Always store or operate the transistor at temperature above -65°C and below +150°C.



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