BD243 transistor

BD243 transistor electrical specification
- BD243 is an NPN silicon medium power transistor device
- Collector to emitter voltage (VCE) is 45V
- Collector to base voltage (VCB) is 45V
- Emitter to base voltage (VEB) is 5V
- Collector current is 6A
- Pulsed collector current is 10A
- Base current is 2A
- Power dissipation is 65W
- DC current gain is 15 to 30hFE
- Junction temperature is between -65 to 150℃
- Thermal resistance is between, the junction to the case is 92℃/W
- Collector to emitter saturation voltage (VCE (SAT)) is5V
BD243 PINOUT

Pin Number | Pin Name | Description |
1 | Base | Base terminal is the trigger for the transistor |
2 | Collector | Current flow through the collector |
3 | Emitter | Current flows through the emitter |
BD243 package
BD243 is a medium power transistor device having a TO-220 three-terminal through-hole device package.
TO-220 is made of epoxy/plastic material which will provide higher temperature capacity at a compact outer covering.
TO-220 package had the provision to attach a heat sink with it for heat transferring ability.
BD243 transistor specification description/ application note:
Here in this section, we explained the electrical specifications of the BD243 medium power transistor, this explanation is very useful for a better understanding of the device.
Voltage specs
The voltage specifications of the BD243 transistor are collector-to-base voltage is 45V, collector-to-emitter voltage is 45V and emitter to the base is 5V, these terminal voltage values indicate it is a medium voltage transistor device.
The collector-to-emitter saturation voltage is 1.5V, this value is important for the switching ability of the device.
Current specs
The collector current value of the BD243 transistor is 6A, this value is the maximum load capacity of the device.
The pulsed collector current value of the BD243 transistor is 10A, this value is calculated at a specific condition.
The base current value of the BD243 transistor is 2A, this current value is the triggering of the device.
Dissipation specs
The power dissipation ability of the BD243 transistor is 65W, this value is mainly dependent on the device package.
Current gain specs
The DC current gain value of the BD243 transistor is 15 to 30Hfe, this value is important for applications like amplification circuits.
Maximum temperature
The maximum temperature value of the BD243 transistor is -65 to +150℃.
Thermal resistance
The thermal resistance value of the BD243 transistor is 1.92℃/W.
BD243 DATASHEET
If you need the datasheet in pdf please click this link
BD243 equivalent
BD243 medium power transistor have equivalent devices such as 2N5497, 2N6121, 2SC1107, TIP131, BD533, 2SD1191, 2SD553, 2N6044, and 2N6291, each of these transistor have the same set of electrical specifications as BD243, so we can easily use as the replacement device.
The applications based on the BD243 transistor are power handling and driver circuits, so the specs such as voltage, current, dc current gain, and power dissipation are important.
BD243 complementary
BD243 NPN medium power transistors have PNP complementary BD244 transistors, and each of them has the same set of electrical specifications, which we can use as push-pull circuits.
BD243 SMD equivalent
BD243 transistors have SMD equivalent devices such as 2STF1550 (SOT-89), BDP947 (SOT-223), and FZT690B (SOT-223), most of the electrical specifications are the same for these devices.
BD243 vs BD533 vs 2N5497
Here in the table below, we listed the electrical specifications of BD243, BD533, and 2N5497, this listing is very useful for a better understanding of these devices and helpful for the replacement process.
Characteristics | BD243 | BD533 | 2N5497 |
---|---|---|---|
Collector to emitter voltage (VCE) | 45V | 45V | 90V |
Collector to base voltage (VCB) | 45V | 45V | 90V |
Emitter to base voltage (VEB) | 5V | 5V | 5V |
Collector to emitter saturation voltage (VCE (SAT)) | 1.5V | 0.8V | 1V |
Collector current (IC) | 6A | 8A | 7A |
Pulsed collector current (ICM) | 10A | - | - |
Base current (IB) | 2A | 1A | 3A |
Power dissipation | 65W | 50W | 50W |
Junction temperature (TJ) | -65 to +150°C | -65 to +150°C | -65 to +150°C |
Transition frequency (FT) | - | - | 0.8MHz |
Gain (hFE) | 15 to 30hFE | 20 to 25hFE | 20 to 100hFE |
Package | TO-220 | TO-220 | TO-220C |
BD243 applications
- Switching applications
- High-power audio amplifier circuit
- BMS circuit applications
- Motor driver circuit
- Battery charger circuit
- General purpose amplifier circuit
Graphical characteristics curves of BD243 transistor

The figure shows the DC current gain characteristics of the BD243 transistor, and the graph plots with DC current gain vs collector current.
At fixed voltage, temperature, and switching values, the DC gain value increases from a higher value and becomes constant for some time then dips at the end.

The figure shows the maximum safe operating area characteristics of the BD243 transistor, the graph plots with collector current, collector-to-emitter voltage, and switching speed.