BC550 NOISE FIGURE NPN
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The BC550 is a widely used, general-purpose NPN bipolar junction transistor (BJT), notable for having the lowest noise figure among the common BC546 to BC550 series.
🎧 BC550 Product Detail
Core Function and Type
Type:NPN Bipolar Junction Transistor (BJT).
Function: Primarily specified for low-noise pre-amplification of small signals. Its low noise characteristics make it an excellent choice for audio circuits and high-gain stages where minimal interference is required. It is also used for low-current switching.
Operating Principle: A small positive current applied to the Base controls a larger current flow from the Collector to the Emitter.
Key Specifications
| Parameter | Typical Value | Description |
| Collector Current (I_C) | 100mA | the maximum continuous current it can switch. |
| Collector-Emitter Voltage (V_CE) | 45V | The maximum voltage it can withstand. (Note: The BC546, BC547, BC548, BC549 series all have different max V_CE ratings). |
| DC Current Gain (h_FE) | 110 to 800 | The high ratio of Collector current to Base current. |
| Noise Figure (NF) | 1.0dB (typical) | This is the defining feature; its extremely low value makes it superior for noise-critical applications. |
| Power Dissipation (P_D) | 500mW | the maximum power it can safely dissipate. |
Package and Pinout
Package: The BC550 is typically supplied in the plastic TO-92 through-hole package.
Pinout: When viewed from the flat side, the standard European pinout is:
Collector
Base
Emitter
Common Applications
The BC550 is preferred over the BC549 and BC548 in applications that require the utmost clarity and quietness:
High-Fidelity (Hi-Fi) Audio Preamplifiers: Used in the most sensitive initial stages of audio equipment to ensure a low-noise floor.
Medical and Scientific Instrumentation: Employed in circuits that amplify very weak signals from sensors where noise could corrupt the data.
High-Gain Amplification Stages: Used where maximum gain is needed with minimal introduction of self-generated noise.