Infineon BC846PN: General-Purpose NPN Bipolar Junction Transistor (BJT) Datasheet and Application Overview
The Infineon BC846PN is a widely used NPN bipolar junction transistor (BJT) belonging to the BC846 series. This surface-mount device (SMD) is housed in a compact SOT-23 package, making it a preferred choice for general-purpose amplification and switching applications in modern electronic designs where board space is at a premium. Its excellent performance characteristics and reliability have made it a staple in consumer electronics, industrial controls, and communication devices.
Key Electrical Characteristics and Datasheet Overview
A review of the BC846PN datasheet reveals its core specifications, which are crucial for circuit designers:
Collector-Emitter Voltage (VCEO): 65 V. This defines the maximum voltage that can be applied between the collector and emitter when the base is open, making it suitable for a variety of low-power circuits.
Collector Current (IC): 100 mA (continuous). This specifies the maximum continuous current the transistor can handle in its collector terminal.
DC Current Gain (hFE): This parameter, which indicates the transistor's amplification capability, is grouped into three classes (A, B, C) with minimum values of 110, 200, and 420 respectively at a specific operating point (IC=2mA, VCE=5V). This allows designers to select a part with the precise gain required for their application.
Power Dissipation (Ptot): 250 mW. This is the maximum power the device can dissipate without exceeding its junction temperature limit.
Transition Frequency (fT): Typically 100 MHz. This high frequency signifies that the BC846PN is capable of operating effectively in high-frequency amplification circuits.
Primary Applications and Circuit Design
The BC846PN excels in two fundamental domains: amplification and switching.
1. Amplification: As a small-signal amplifier, the transistor is used to amplify weak AC or DC signals in stages such as:
Audio pre-amplifiers
Signal processing circuits
RF amplifiers (within its frequency range)
In a typical common-emitter amplifier configuration, the BC846PN provides significant voltage gain, making small input signals larger and usable for subsequent stages.
2. Switching: The transistor acts as a fast, solid-state switch to control larger loads with a small control signal. Key switching applications include:
Driving relays, LEDs, and small motors
Level shifting and interface logic
Pulse generation
In this mode, the transistor is operated in saturation (ON) and cut-off (OFF) regions. A key design consideration is ensuring sufficient base current is provided to drive the transistor into full saturation, minimizing the voltage drop between collector and emitter (VCE(sat)).
Advantages of the BC846PN
The popularity of the BC846PN stems from several advantages:
High Gain and Low Noise: Offers excellent signal amplification with minimal added noise.
Complementary Pairing: It is commonly available with its PNP complement, the BC856PN, simplifying the design of push-pull and complementary output stages.
Proven Reliability: As a product from Infineon, a leader in semiconductor technology, it offers high quality and long-term reliability.
The Infineon BC846PN stands as a quintessential general-purpose NPN transistor, offering an optimal balance of voltage handling, current gain, and switching speed. Its SOT-23 package and consistent performance make it an indispensable component for designers tackling a vast array of analog and digital circuit challenges, from simple load switching to complex signal amplification.
Keywords: NPN Transistor, General-Purpose Amplification, SOT-23 Package, High-Frequency Switching, Bipolar Junction Transistor (BJT)
