BC108 transistor

BC108 transistor
BC108 transistor

BC108 specification

  • BC108 is an NPN planer epitaxial BJT transistor device
  • Collector to emitter voltage is 25V
  • Collector to base voltage is 30V
  • Emitter to base voltage is 5V
  • Collector current is 2A
  • Power dissipation is 6W/℃
  • DC current gain is 110 to 800hFE
  • Current gain-bandwidth (FT) is 150MHz
  • Junction temperature is between -65 to 200℃
  • Thermal resistance junction to ambient is 175℃/W
  • Collector to emitter saturation voltage (VCE (SAT)) is25 to 0.60mV
  • Noise figure (NF) is 10dB
  • Output capacitance (Cob) is 5pF
  • Low power transistor device

BC108 transistor Pinout

BC108 transistor Pinout
BC108 transistor Pinout
Pin Number Pin Name Description
1 Emitter  Current flows through the emitter
2 Base Base terminal is used to trigger the device
3 Collector Current flow through the collector 


BC108 package

The BC108 NPN bipolar junction transistor device has a TO-18 package, it is a low-power semiconductor three-terminal device.

TO-18 package is made up of metal covering cans outside, the heat resistance of this package is higher and the outer covering will act as the heat sink.

And at the TO-18 package, we have a small portion of metal marking them for the terminal counting, starting from the emitter, base, and collector.

BC108 NPN transistor electrical specification description

In this section, we explain the electrical specifications of the BC108 transistor, this is very useful for better understanding.

Voltage specs

The voltage specifications of the BC108 transistor are collector to emitter voltage is 25V, collector to base voltage is 30V, and emitter to base voltage is 5V.

The collector to emitter saturation voltage is 0.25V to 0.60V, this voltage values indicate the region switching of the device.

The voltage specifications of the BC108 transistor device show that it is a low voltage and low power application device, used for project-based circuits.

Current specs

The collector current value of the BC108 NPN transistor is 0.2A, it is the load capacity of the device.

Dissipation specs

The power dissipation of the BC108 transistor is 0.6W/℃, the dissipation ability is been mainly dependent on the device package.

Current gain specs

The DC current gain value of the BC108 transistor is 110 to 800Hfe, it is the dc current value at a constant voltage value, which is the amplification ability of a transistor.

Transition frequency

The bandwidth transition frequency value of the BC108 is 150MHz.

Junction temperature/ storage temperature

 The temperature range of the BC108 transistor is -65 to 200℃.

Thermal resistance between junctions to case

The thermal resistance of the BC108 transistor is 175℃/W.

Noise figure

The noise figure value of the BC108 transistor is 10dB

Output capacitance

The output capacitance value of the BC108 transistor is 4.5Pf

BC108 transistor DATASHEET

If you need the datasheet in pdf please click this link

BC108 equivalent

The BC108 NPN transistor has equivalent devices BC547, BC548, 2N3904, BC107, BC549, and 2N3053, every one of them has similar electrical specifications.

For the equivalent replacement process mainly we need to check and verify the voltage specs and PINOUT details because at the circuit level these two specs are very important and dangerous.

BC108 NPN complementary pair

The BC108 NPN transistor has a complementary pair PNP device BC178, both these transistors have the same and opposite specifications.

SMD version of BC108 NPN transistor

The MMBTH10 (SOT-23) is the SMD version equivalent transistor of BC108 transistor, power dissipation value is the only difference at SMD transistor.

BC108 vs BC109 vs BC548

In this comparison table, we compare the electrical specifications of BC108, BC109, and BC548, this listing will help us for a better idea about the devices and support us in the replacement process

Collector to base voltage (VCB)     30V30V30V
Collector to emitter voltage (VCE)25V25V30V
Emitter to base voltage (VEB)5V5V5V
Collector to emitter saturation voltage (VCE (SAT))0.25 to 0.60V   0.25 to 0.60V90 to 600mV
Collector current (IC)0.2A0.2A100mA
Power dissipation0.6W/℃0.6W500mW
Junction temperature (TJ)-65 to +200°C-65 to +200°C-65 to +150°C
Transition frequency (FT)150MHZ150MHZ   300MHz
Gain (hFE)110 to 800hFE110 to 800hFE110 to 800hFE
Output capacitance4.5pF5Pf3.5 to 6pF
Noise figure10dB4dB 2 to 10dB
PackageTO-18TO-18    TO-92

The BC108 and BC109 are similar transistor devices with the same electrical specifications, BC548 is a little bit different, so when we compare they have higher electrical characteristics.

BC108 transistor applications

  • LED dimmer
  • Switching applications
  • Preamp
  • Power amplifier circuit
  • High-frequency switching circuit
  • Modulator & demodulator for RF frequency circuit
  • Low noise signal processing
  • Low noise circuit

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