BD138 transistor
BD138 specification
- BD138 is a PNP epitaxial silicon transistor device
- Collector to emitter voltage (VCE) is -60V
- Collector to base voltage (VCB) is -60V
- Emitter to base voltage (VEB) is –5V
- Collector current is -1.5A
- Pulsed collector current is -3A
- Base current is –5A
- Power dissipation is 5W
- DC current gain is 25 to 250hFE
- Junction temperature/ storage temperature is between -55 to 150℃
- Collector to emitter saturation voltage (VCE (SAT)) is -0.5V
- Transition frequency (FT) is 100MHz
- Medium power transistor device
BD138 Pinout
| Pin Number | Pin Name | Description |
| 1 | Emitter | Current flows through the emitter |
| 2 | Collector | Current flow through the collector |
| 3 | Base | The base terminal is used to trigger the transistor |
BD138 transistor package
The BD138 is a medium power transistor device that has a TO-126 package, it is a transistor package made with epoxy or plastic material with a metal coating at the backside.
The TO-126 package is compact and lite weighted due to building material, the hole at the middle is used to attach the heat sink and the metal covering will transfer the heat from the transistor to the heat sink.
BD138 transistor electrical specification description
In this section we try to explain the electrical specifications of the BD138 transistor, this explanation is really helpful for a better understanding of the device and helps for the replacement process.
Voltage specs
The voltage specs of the BD138 transistor are collector to base voltage is -60V, collector to emitter voltage is -60V, and emitter to base voltage is -5V, this is the terminal voltage specifications.
The collector to emitter saturation voltage is -0.5V, which is the lowest value for a transistor device.
Overall voltage specifications of the BD138 transistor show that it is a medium power device having power applications.
Current specs
The collector current value of the BD138 transistor is -1.5A, it is a high load value for a transistor device.
The pulsed collector current value of the BD138 transistor is -3A and the base current value is -0.5A.
The overall current value of the BD138 transistor shows that it is a device that has high loading capacity, so we can use them for driving and loading applications.
Dissipation specs
The power dissipation of the BD138 transistor is 12.5W, the dissipation capacity of the device is due to the transistor package.
Current gain specs
The current gain value of the BD138 transistor is 25 to 250Hfe, the moderate current gain values indicate it is an amplifier device.
Junction temperature
The junction temperature and operating temperature BD138 transistor are between -55 to 150℃.
Transition frequency
The transition frequency value of the BD138 transistor is 100MHz.
BD138 transistor DATASHEET
If you need the datasheet in pdf please click this link
BD138 equivalent
The transistor devices such as BD140, BD170, BD180, BD229, MJE254, BD788, MJE235, BD190, and 2SB1354 are the equivalent transistors of BD138.
The electrical characteristics and physical specs of these transistors are the same as the BD138 transistor, this is why we can use them as the replacement.
BD138 complementary pair
The BD137 NPN transistor is complementary to the BD138 PNP transistor, the electrical specs are opposite. This pair of transistor devices are been used in many applications.
SMD version transistor of BD136 transistor
The BCP52 (SOT-223) is the SMD equivalent of the BD138 transistor, the electrical specification of this transistor is the same as the through hole model.
BD138 vs BD140 vs BD380
In this table, we try to compare the electrical specs of BD138, BD140, and BD380 transistor devices, this comparison is really helpful for a better understanding of this device and also for the replacement process.
| Characteristics | BD138 | BD140 | BD380 |
|---|---|---|---|
| Collector to emitter voltage (VCE) | -60V | -80V | -80V |
| Collector to base voltage (VCB) | -60V | -80V | -100V |
| Emitter to base voltage (VEB) | -5V | -5V | -5V |
| Collector to emitter saturation voltage (VCE (SAT)) | -0.5V | -0.5V | -1V |
| Collector current (IC) | -1.5A | -1.5A | -2A |
| Power dissipation | 12.5W | 12.5W | 25W |
| Junction temperature (TJ) | -55 to +150°C | -55 to +150°C | -55 to +150°C |
| Transition frequency (FT) | 100MHz | - | - |
| Gain (hFE) | 25 to 250hFE | 20 to 250hFE | 20 to 375hFE |
| Package | TO-126 | TO-126 | TO-126 |
The BD138 and BD140 transistors have the same electrical specifications, so both of them are replaceable.
The BD380 is a PNP transistor having little bit higher electrical specifications than the BD138 transistor.
BD138 transistor applications
- Medium power linear and switching applications
- Audio amplifier circuit
- Battery charger circuit
- Motor driver circuit
- Power supply applications
- H-bridge applications
Characteristics curves of BD138 transistor
The figure shows the DC current gain characteristics of the BD138 transistor, the graph is plotted with dc current gain vs collector current.
At a constant collector to emitter voltage, the dc current gain increases from a higher value and becomes constant opposition and decreases at some time with respect to collector current.
The figure shows the collector to emitter saturation voltage characteristics of the BD138 transistor, the graph is plotted with the collector to emitter saturation voltage.
The graph is plotted at two different values, the collector current value increases slightly with respect to the voltage value and increases just as an inverted parabolic shape.
The figure shows the safe operating area of the BD138 transistor, the graph is plotted with collector current vs collector to emitter voltage and pulses.
