BC517 NPN Transistor Pinout Datasheet

Introduction

The BC517 is a high-gain NPN Darlington transistor designed for use in low current switching and signal amplification applications. It is one of the most popular members of the BC51x Darlington transistor family, offering extremely high DC current gain and excellent sensitivity. The BC517 integrates two NPN transistors internally in a Darlington configuration, providing a very high gain (typically between 30,000 and 100,000) and allowing it to amplify very small base currents into significant collector currents. This makes it an ideal choice for microcontroller outputs, logic-level switching, and sensor signal amplification.

Because of its low input current requirement and high output capability, the BC517 is commonly used to interface digital circuits with relays, solenoids, lamps, or LEDs. It operates in the TO-92 package, which ensures compact size, reliable thermal performance, and easy integration into PCB-based designs. The transistor also exhibits low collector-emitter saturation voltage and can handle moderate load currents efficiently, making it suitable for both hobbyist and industrial electronic applications.

BC517 NPN Transistor

In addition to switching, the BC517 performs exceptionally well in low-frequency amplification, preamplifier, and signal conditioning circuits. It can be directly driven by TTL or CMOS logic devices and used where small input signals need large output currents. Its high gain and Darlington design make it particularly useful in automation systems, LED drivers, and digital interfaces where minimal input drive is available.

BC517 Pinout

Pin Configuration

Key Features

• NPN Darlington transistor with extremely high gain
• DC current gain up to 100,000 typical
• Low base current required for operation
• Low collector-emitter saturation voltage
• Compact TO-92 plastic package for easy PCB mounting
• Ideal for driving relays, LEDs, and solenoids
• Excellent for digital interface and microcontroller control
• Reliable thermal and electrical performance
• High sensitivity for low input signal applications

Characteristics

• Transistor Type: NPN Darlington
• Collector-Emitter Voltage (Vceo): 30V
• Collector-Base Voltage (Vcbo): 30V
• Emitter-Base Voltage (Vebo): 5V
• Maximum Collector Current (Ic): 500mA
• DC Current Gain (hFE): 30,000 to 100,000 typical
• Collector-Emitter Saturation Voltage (Vce(sat)): 1V typical
• Transition Frequency (fT): 100MHz typical
• Power Dissipation (Ptot): 625mW
• Operating and Storage Temperature Range: -65°C to +150°C
• Package Type: TO-92

Comparison of BC516 PNP, BC517 NPN

• BC517 is an NPN Darlington transistor, while BC516 is its PNP counterpart, designed for complementary circuit use.
• The BC517 activates when a positive voltage is applied to the base, whereas the BC516 operates with a negative control signal.
• Both transistors offer very high DC gain, enabling control of large loads using very small input currents.
• BC517 is typically used for sourcing current from a positive supply, while BC516 is used for sinking current to ground.
• Together, they can be combined in push-pull amplifiers, driver circuits, and complementary logic-level switching applications for efficient and balanced performance.

More Circuit Layouts

Key Applications of BC517 Transistor

• Low current signal amplification
• Relay, solenoid, and motor driver circuits
• LED and lamp control from logic outputs
• Digital and microcontroller switching interfaces
• Low-frequency preamplifier stages
• Automatic control and sensing systems

PNP Complementary Transistor

• The BC516 is the PNP complementary transistor to the BC517. When used together, they form complementary Darlington pairs, ideal for push-pull amplifier designs and high-sensitivity switching circuits that require symmetrical performance for positive and negative signals.

Equivalent of BC517 NPN Transistor

• 2N6426, 2N6427, MPSA65, BCX51, 2SA1006
  These alternatives may vary in gain, voltage, and package type, but they provide similar electrical performance.

Always verify the pin configuration and ratings before substitution.

Datasheet of BC517 NPN Transistor

Click the following Button to download the datasheet of BC517 Transistor :

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