A transistor is a semiconductor device having three terminals that are used to amplify or switch electronic signals. In this blog, we will be discussing the different BCXXX transistors their applications, pinout, and the difference between them.
BC557
The BC557 is a semiconductor device that is used to amplify or switch electronic signals as well as electrical power. BC557 transistor is a PNP type Bipolar junction Transistor that comes in a TO-92 package. This transistor's hFE ratings range from 125 to 800, making it perfect for use as an amplifier in electronic circuits such as audio signal amplification. The collector dissipation is 500 milliwatt. When used as a switch for loads less than 100mA, this transistor works well. For this transistor, the VCE value is -45V.
Application
- It is used in different driver modules such as LED driver, relay driver, etc.
- It is used in amplifier modules such as signal, audio, etc.
- Darlington pair
- This transistor is used for amplification & switching purposes
- It is used to control the flow of current within motors
- It is used in robot & instrumentation based projects
- Used to drive below 0.1mA/100mA of loads
BC548
The BC548 is an NPN transistor, when the base pin is held at the ground, the collector and emitter are left open (reverse biased), and when a signal is provided to the base pin, the collector and emitter are closed (forward biased). The gain value of the BC548 is 110 to 800, which determines the transistor's amplification capacity. The maximum amount of current that can flow through the Collector pin is 500mA, we can't use this transistor to connect loads that need more than 500mA. We have to supply current to the base pin of a transistor to bias it, and this current (IB) should be limited to 5mA.
When fully biased, this transistor can allow a maximum of 500mA to flow between the collector and emitter. The voltage allowed across the Collector-Emitter (VCE) or Base-Emitter (VBE) could be 200 or 900 mV. The BC548's maximum collector dissipation is 626 miliWatt, which makes it ideal for use as a small amplifier.
Applications
- Driver Modules like Relay Driver, LED driver, etc.
- Amplifier modules like Audio amplifiers, signal Amplifiers, etc
- Used in Darlington pairs to amplify weak signals.
- It can be employed in sensor circuits.
BC337
The BC337 is a general-purpose transistor that is mostly used for audio amplification and switching. It is an NPN transistor with a maximum gain of 630 and belongs to the NPN transistor family It. It can also switch loads up to 45V and 800mA, making it a versatile transistor. The BC337 is a NPN transistor that is commonly used in low power amplifier circuits. It has three-part names, BC337-16 has a gain value of 100 to 250, BC337-25 has a gain value of 160 to 400, and BC337-40 has a gain value of 250 to 630. Apart from the gain value, all three component numbers have similar parameters. It can drive loads up to 800mA based on the continuous collector current of 800mA. The voltage between the collector and the emitter is 45 volts, while the voltage between the collector and the base is 50 volts. The voltage between the emitter and the base is 5V. 100MHz is the transition frequency. Digital circuits, such as microcontroller circuits, can simply control it due to their low base trigger voltage. If you're looking for a transistor for audio amplification, the BC337 is a good option.
Applications
- Low power audio amplifiers
- Small signal amplifiers
- Audio frequency Driver
- Amplifier Output Stage
- General purpose switching
BC857
The BC857 transistor is a PNP general-purpose transistor. This transistor's primary uses are general-purpose switching and amplification. The BC857 PNP transistor is packaged in a tiny SOT-23 package. It operates on low current and voltage. It's an SMD version of the BC557 TH Transistor. BC857 has a gain value of 125 to 800, which determines the transistor's amplification capacity. We have to supply current to the base pin to bias the transistor; this current (IB) is not more than 200mA, and the voltage across the base-emitter pin should be 5V. This transistor can allow current to pass across the collector and emitter when it is fully biased.
Applications
- Simple switching applications
- Microphone preamplifiers
- Lighting systems
- Relay drivers
- Audio Amplifiers
- Signal Amplifiers
BC177
In the TO-18 metal case, the BC177 and BC177B are silicon planar epitaxial PNP transistors. They are suitable for use in driver stages, low noise input stages, and signal processing circuits of television receivers. The VCE of this transistor is -50V, and the continuous collector current is -100mA. It can be used as a signal switching transistor for small signals. It has a -5V low base voltage.
The BC177 transistor is a very versatile device that can be used in a wide range of applications. It is mostly utilized when you want a simple switching device for low power loads simultaneously, it may also be used in high-frequency RF applications, and its gain-bandwidth product and metal construction make it appropriate for a wide range of applications. The transistor is cheap and simple to use, it is ideal for random switching devices. The BC177 is also a basic power amplifier that can be used to boost low-power signals.
When this transistor is biased, it can allow a maximum current of -200mA across the CE(Collector-Emitter) Junction this is known as the saturation state of the transistor, and driving a load that consumes more current than 200mA may permanently damage the device. A transistor is a current-controlled device, therefore when the base current is removed, the transistor becomes entirely off; at this point, the transistor is in its Cut-off Region, and no current flows through the C-E junction. The gain of the BC177 Transistor ranges from 125 to 500. This value affects the transistor's amplification capacity; the maximum current that can be passed through it is 200mA, which when combined with the gain value makes this transistor ideal for RF applications.
Applications
- Simple switching applications
- Microphone preamplifiers
- Lighting systems
- Relay drivers
- Audio Amplifiers
- Signal Amplifiers
BC639
The BC639 is a TO-92 package NPN transistor with a VCE of 100V and a continuous collector current of 1A. This transistor can be used in moderately high voltage switching applications with this characteristic and 1W total power dissipation.
The BC639 transistor is a very versatile device that can be used in a wide range of applications. This transistor can be used to switch devices with moderately high voltages, such as a tiny DC-DC converter or the pre-or mid-amplifier stage of a power amplifier (power amplifiers typically utilize 60 to 120V DC).
When this transistor is biased, it can allow a maximum current of 1A across the CE(Collector-Emitter) Junction this state of the transistor is known as the saturation state, and driving a load that consumes more current than 1A may permanently damage the device also, during the design process, you should be aware that this device's maximum dissipation is 1W; power greater than that can damage the device.
As you may know, a transistor is a current-controlled device, thus when the base current is removed, the transistor turns completely off; at this point, the transistor is in its cut-off region/cut-off state, with no current flowing through the C-E junction.
The BC639 transistor has a gain range of 40 to 160, which determines the transistor's amplification capacity. The maximum current that can be passed through this transistor is 1.5A, which when combined with the gain value, makes it an excellent choice for moderate-high voltage applications.
The base of an NPN transistor will be 0V under normal conditions and without external impact. As we all know, the working principle of an NPN transistor is that when the base voltage is zero, the transistor is in a high resistance condition. To totally switch on the device, a tiny amount of current must flow out of the base of the transistor. For example, in order to flow 1000mA of current via the collector to the emitter, 50mA of current must travel through the base of the transistor.
Applications
- Simple switching applications
- Microphone preamplifiers
- Lighting systems
- Relay drivers
- Audio Amplifiers
- Signal Amplifiers
BC817 NPN Transistor (SMD)
BC817 is a general-purpose semiconductor device that may be used to amplify, switch, or control a signal or power. Because the BC817 is an NPN transistor, we must apply a little amount of positive voltage to the transistor's base via a current limiting resistor known as an RB (Base Resistor). When the proper amount of current passes through the transistor's base, the transistor will switch on.
This transistor has a maximum collector current of 500mA and a maximum emitter-base voltage of 45V. The collector-emitter voltage of this transistor is 45 volts, and the collector-base voltage is 5 volts. This transistor can sustain temperatures of up to 150°C. Before selecting this transistor, keep in mind that, due to its size, it can deliver a lot of power, thus suitable thermals are required.
When this transistor is biased, it can allow a maximum current of 500mA and a maximum power of 0.46W over the CE(Collector-Emitter) Junction; this is known as the saturation state, and applying a load that consumes more current than 500mA may harm the device. A transistor is a current-controlled device, thus when the base current is removed, the transistor turns off completely. At this point, the transistor is in its Cut-off Region, and the Base Emitter voltage maybe around 500 mV.
Applications
BC817 Transistor is a very versatile device, its high-frequency range, large bandwidth makes it suitable for many different applications.
- LED dimmers or flashers
- Switching Applications
- Preamplifier for Power Amplifier
- High-frequency switching
- Modulator and Demodulator for RF frequency
BC547 N-Channel General Purpose Transistor SMD
The BC547 is an SMD SOT23-3 package NPN Transistor with a collector current of 100mA and a VCE of 45V. It can be used as a signal switching transistor for small signals. It has a low base voltage of 6V . The transistor will switch on when a positive voltage is applied to the base pin. This transistor's maximum gain is 800, which determines the device's amplification factor. The maximum base current is 5mA, and the collector-emitter current is 100mA any current greater than these values may destroy the device.
Applications
- LED dimmers or flashers
- Switching Applications
- Preamplifier for Power Amplifier
- High frequency switching
- Driver Modules like Relay Driver, LED driver etc.
PINOUT
| Pin Number | Pin Name | Description |
| 1 | Collector | Current flows in through collector |
| 2 | Base | Controls the biasing of transistor |
| 3 | Emitter | Current Drains out through emitter |
DIFFERENCE
| Diode | BC557 | BC337 | BC547 SMD | BC177 | BC639 | BC548 | BC857 | BC817 |
| Type | PNP | NPN | NPN | PNP | NPN | NPN | PNP | NPN |
| Package | TO-92 | TO-92 | SOT23-3 | TO-18 Metal Can Package | TO-92 | TO-92 | SOT-23 | SOT-323/SC70 |
| Max. DC Current Gain (hFE) | 800 | 630 | 800 | 500 | 160 | 800 | 800 | 600 |
| Continuous collector current (IC) | -100mA | 800mA | 100mA | -100mA | 1A | 500mA | 0.1A | 500mA |
| Emitter Base Voltage (VBE) | -5V | 5V | 6V | -5V | 5V | 5V | 5V | 5V |
| Collector base Voltage | -50V | 50V | 45V | 50V | 50V | 30V | 50V | 50V |
| Power dissipation | 500mW | 625mW | 0.3W | 0.3W | 1W | 625mW | 250mW | 0.46W |
| Transition Frequency | 300MHz | 100MHz | 100MHz | 200MHz | 100MHz | 150MHz | 150MHz | 100MHz |
| Collector Capacitance | 4pF | 12pF | 5pF | 5pF | 20pF | 6pF | 4.5pF | 5pF |
| Noise | 2-10 dB | 2-10 dB | 2-10 dB | 2-10 dB | 2-10 dB | 2-10 dB | 2dB | 2dB |
| Max. Operating Temperature | 150 °C | 150 °C | 175 °C | 175 °C | 150 °C | 175 °C | 150°C | 175 °C |
You Can Purchase the Following Transistors from HNHCart.com:
- BC557 PNP General Purpose Transistor
- BC548 NPN General Purpose Transistor
- BC337 NPN General Purpose Transistor
- BC547 NPN General Purpose Transistor
- BC857 PNP General Purpose Transistor