Infineon BC847S General-Purpose NPN Transistor: Datasheet, Application Circuits, and SMD Package Specifications
The Infineon BC847S is a widely used NPN bipolar junction transistor (BJT) housed in a compact SMD (Surface-Mount Device) package. Designed for general-purpose amplification and switching applications, this transistor is a fundamental component in modern electronic design, offering reliable performance in a miniaturized form factor.
Key Datasheet Specifications and Features
The BC847S is part of Infineon’s extensive BC847 series, characterized by its high reliability and performance consistency. Key absolute maximum ratings and electrical characteristics from its datasheet include:
Collector-Emitter Voltage (VCEO): 45 V
Collector Current (IC): 100 mA
Total Power Dissipation (Ptot): 250 mW
DC Current Gain (hFE): This is grouped into gain classes (e.g., A, B, C), with the BC847S typically offering a range from 110 to 800, depending on the specific variant, ensuring a suitable option for various amplification needs.
Transition Frequency (fT): 300 MHz (typical), making it suitable for high-speed switching and RF amplification.
Low Noise Figure: Ideal for pre-amplifier stages in audio and signal processing circuits.
SMD Package Specifications: SOT-23
The "S" in BC847S denotes its surface-mount package. It is housed in the ubiquitous SOT-23 package. This package is incredibly small, with three gull-wing leads, making it ideal for high-density PCB designs. Its compact size allows for automated assembly processes, which is critical for mass production. The package is designed to withstand the high temperatures of reflow soldering, ensuring robust manufacturing.
Application Circuits
The BC847S is versatile and can be configured in several classic transistor circuit topologies:
1. Low-Side Switch: One of the most common applications. The transistor is used to switch a load (e.g., a relay, LED, or motor) on and off by applying a control signal to its base. A base resistor is crucial to limit current. The load is connected between the collector and the positive supply voltage (VCC), while the emitter is connected to ground.
2. Common-Emitter Amplifier: This circuit configuration provides voltage gain. It is used for amplifying small AC signals. The operating point is set by a voltage divider bias network on the base (resistors R1 and R2), with a collector resistor (RC) and an emitter resistor (RE) for stability. The amplified output signal is taken from the collector.
3. Darlington Pair: For applications requiring very high current gain, two BC847S transistors can be connected in a Darlington configuration. This pairs the gains of the two transistors (hFE(total) ≈ hFE1 hFE2), enabling the switching of a higher current load with a very small input base current.
The Infineon BC847S stands as a testament to the enduring utility of the BJT in an SMD world. Its combination of high gain, good frequency response, and the compact SOT-23 package makes it an indispensable component for designers. Whether it’s driving LEDs, interfacing between microcontrollers and higher-power devices, or amplifying sensor signals, the BC847S provides a cost-effective and reliable solution. Its detailed datasheet provides engineers with all the necessary parameters to design robust and efficient circuits for a vast array of consumer, industrial, and communication applications.
Keywords:
1. NPN Transistor
2. SMD Package
3. SOT-23
4. General-Purpose Amplification
5. Switching Applications
