BC549 transistor
BC549 transistor electrical specification
- BC549 is an NPN epitaxial silicon transistor device
- Collector to emitter voltage is 30V
- Collector to base voltage is 30V
- Emitter to base voltage is 5V
- Collector current is 100mA
- Pulsed collector current is 200mA
- Maximum base current is 200mA
- Power dissipation is 500mW
- DC current gain is 110 to 800hFE
- Current gain-bandwidth (FT) is 100 to 300MHz
- Junction temperature is between -65 to 150℃
- Collector to emitter saturation voltage (VCE (SAT)) is 90 to 250mV
- Noise figure (NF) is 4 to 4dB
- Output capacitance (Ciss) is 5 to 6pF
- Thermal resistance, junction ambient is 250℃/W
- Low current
- Low voltage
BC549 transistor Pinout
| Pin Number | Pin Name | Description |
| 1 | Collector | Current flows through the emitter |
| 2 | Base | Base is used as the trigger for the transistor |
| 3 | Emitter | Current flow through the collector |
BC549 transistor package
The BC549 transistor had two types of packages TO-92 and SOT54, both these transistor packages are much similar to each other.
The TO-92 and SOT-54 packages are made with epoxy/plastic material, these materials will help us to have high resistance properties.
Both the packages are compact and lite weighted, the only difference between these transistor packages is the shape.
Marking the case
This transistor component had a “BC549” marking on its case
BC549 transistor electrical specification description/ application
In this section we try to explain the electrical specifications of the BC549 transistor, this will help us for a better understanding of this transistor device.
This description provides us with a better view of the BC549 transistor and supports us in the replacement process.
Voltage specs
The terminal voltage specs of BC549 transistor are collector to base voltage and collector to emitter voltage is 30V and emitter to base voltage is 5V, the voltage specs show it is a general-purpose device.
The collector to emitter saturation voltage is 90 to 250Mv, it is the switching voltage for the transistor and it is less than the base voltage.
Overall voltage specifications of BC549 transistor show it is a general-purpose device, mainly used for low-power applications.
Current specs
The collector current value of the BC549 transistor is 100mA, it is the maximum load capacity of this device.
The maximum pulsed collector current is 200mA, the pulsed current value is double that of the current value because they are been calculated in a specific condition.
The maximum base current value is 200mA, it is the current value withstood by the base terminal.
Overall current specifications of BC549 transistors show that they had enormous applications in switching and driver circuits.
Dissipation specs
The power dissipation of the BC549 transistor is 500mW, it is the power dissipation of the device.
The dissipation ability of the device mainly depends on the device package and applications.
Current gain specs
The current gain value of the BC549 transistor is 110 to 800hFE, this is why these transistors are used for low-power amplifiers and switching applications.
The applications like amplifiers utilize DC current gain property of the transistor at the circuits.
Transition frequency
The bandwidth transition frequency value of the BC549 transistor is 100 to 300MHz, it is the frequency range of the transistor.
Junction temperature
With the junction temperature of -65 to 150℃, the heat capacity of the transistor is mainly dependent on the case.
Thermal resistance
The thermal resistance of the BC549 transistor case is 250℃/W
Noise figure
The noise figure value of the BC549 transistor is 1.4 to 4dB
Output capacitance
The output capacitance value of the BC549 transistor is 3.5 to 6pF
BC549 transistor DATASHEET
If you need the datasheet in pdf please click this link
BC549 transistor equivalent
The transistors such as BC547, BC548, and BC550 are the equivalent transistors of the BC549 device.
The electrical specifications of each of these three transistors are almost the same as the BC549 transistor, this is why we can use them as the replacement.
BC549 is a general-purpose device mainly used for low-power circuits, before the replacement process we need to check and verify the PINOUT details of each transistor.
BC549 complementary pair
The transistor devices BC559 and BC560 are the PNP complementary pair transistor of BC549.
The electrical specifications of the as same, so we can use them to make Darlington pair network applications.
BC549 transistor SMD version
The SMD version transistors such as BC848 (SOT-23), BC848W (SOT-323), BC849 (SOT-23), and BC849W (SOT-323) are the SMD equivalent of the BC549 transistor.
Almost all the electrical specifications of these transistors are the same, but the dissipation capability is different.
The BC549 SMD version transistors had many applications on surface mount boards.
BC549 vs BC547 vs 2N3904
In this table, we try to list the electrical specifications of BC549, BC547, and 2N3904 transistors, this is helpful for the replacement process.
| Characteristics | BC549 | BC547 | 2N3904 |
|---|---|---|---|
| Collector to base voltage (VCB) | 30V | 50V | 60V |
| Collector to emitter voltage (VCE) | 30V | 45V | 40V |
| Emitter to base voltage (VEB) | 5V | 6V | 6V |
| Collector to emitter saturation voltage (VCE (SAT)) | 90 to 250mV | 250 to 600mV | 0.2 to 0.3V |
| Collector current (IC) | 100mA | 100mA | 200mA |
| Power dissipation | 500W | 500mW | 625mW |
| Junction temperature (TJ) | -65 to +150°C | -65 to +150°C | -55 to +150°C |
| Transition frequency (FT) | 100 to 300MHZ | 300MHZ | 300MHz |
| Gain (hFE) | 110 to 800hFE | 110 to 800hFE | 30 to 300hFE |
| Output capacitance | 3.5 to 6pF | 3.5 to 6pF | 4pF |
| Noise figure | 1.4 to 4dB | 2 to 10dB | 5dB |
| Package | TO-92/SOT-54 | TO-92 | TO-92 |
BC549 transistor applications
- Low noise stage in audio frequency applications
- Linear audio amplifier
- Darlington pair circuit
- Sensor circuit
- Oscillator circuit
- Comparator circuit
- Current mirror circuit
- Multi-vibrator circuit
- Impedance buffering circuit
- Low power switching applications
- Small signal amplifier
- The LED sequence controller circuit
Characteristics curves of BC549 transistor
The figure shows the static characteristics of the BC549 transistor, the graph is plotted with collector current vs collector to emitter voltage.
At different base current values, the collector current produces a curve with respect to the collector to emitter voltage.
The current curves start at the lowest value to a higher value.
The figure shows the DC current gain characteristics of the BC549 transistor, the graph is plotted with dc current gain vs collector current.
At the fixed collector to an emitter voltage value, the DC current gain value started slowly and dips at the end.
Frequency divider circuit using a BC549 transistor
The figure shows the frequency divider circuit using a BC549 transistor as the main component, the circuit consists of BC549, 1N4148 diode, inductor, and resistor & capacitor.
The circuit works just like the Colpitts oscillator, it is an LC-based oscillator network.
