BC550 Bipolar Transistors – BJT NPN
The BC550 is a low-noise, general-purpose NPN epitaxial silicon transistor in a TO-92 package. It is optimized for amplifier and switching applications where low noise and moderate voltage handling (up to 45 V collector–emitter) are required
Features
- Switching and Amplifier functionality
- High‑Voltage capability (VCEO up to 45 V)
- Low‑Noise performance (noise figure down to 1.4 dB)
- Complementary to BC556, BC557, BC558, BC559, and BC560 series
- Pb‑Free Device, RoHS‑compliant
Specifications
Absolute Maximum Ratings (TJ = 25 °C)
| Parameter | Symbol | Value | Unit |
|---|---|---|---|
| Collector–Base Voltage | VCBO | 50 | V |
| Collector–Emitter Voltage | VCEO | 45 | V |
| Emitter–Base Voltage | VEBO | 5 | V |
| Collector Current (DC) | IC | 100 | mA |
| Collector Power Dissipation | PC | 500 | mW |
| Junction Temperature | TJ | 150 | °C |
| Storage Temperature Range | TSTG | –65 to +150 | °C |
Electrical Characteristics (TC = 25 °C)
| Parameter | Symbol | Test Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|---|
| Collector Cut‑off Current | ICBO | VCB = 30 V, IE = 0 | — | — | 15 | nA |
| DC Current Gain | hFE | VCE = 5 V, IC = 2 mA | 110 | — | 800 | — |
| VCE(sat) (low‑current) | — | IC = 10 mA, IB = 0.5 mA | — | 90 | 250 | mV |
| VCE(sat) (high‑current) | — | IC = 100 mA, IB = 5 mA | — | 250 | 600 | mV |
| VBE(on) | — | VCE = 5 V, IC = 2 mA | 580 | 660 | 700 | mV |
| VBE(on) (at 10 mA) | — | VCE = 5 V, IC = 10 mA | — | 720 | — | mV |
| VBE(sat) | — | IC = 10 mA, IB = 0.5 mA | — | 700 | — | mV |
| VBE(sat) (high‑current) | — | IC = 100 mA, IB = 5 mA | — | 900 | — | mV |
| Current Gain Bandwidth | fT | VCE = 5 V, IC = 10 mA, f = 100 MHz | — | 300 | — | MHz |
| Output Capacitance | Cob | VCB = 10 V, IE = 0, f = 1 MHz | — | 3.5 | 6.0 | pF |
| Input Capacitance | Cib | VEB = 0.5 V, IC = 0, f = 1 MHz | — | 9 | — | pF |
| Noise Figure (BC550) | N.F. | VCE = 5 V, IC = 200 µA, f = 1 kHz, RG = 2 kΩ | 1.4 | — | 3.0 | dB |
Applications
- Audio Amplifiers and Preamplifiers: Provides clean, low-noise signal amplification.
- Signal Amplification: Ideal for sensors, detectors, and other sensitive devices.
- Switching Circuits: Used in digital logic and control systems.
- Oscillator Circuits: Suitable for generating signals in various frequency ranges.
