BC517 NPN Darlington Transistor Technical Summary

Overview

The BC517 is an NPN Darlington transistor housed in a TO-92 (SOT54) plastic package. It is designed for applications requiring high current gain and moderate power handling. The Darlington configuration combines two bipolar transistors in a cascaded arrangement, providing extremely high current gain compared to a single transistor. This makes the BC517 ideal for driving high-current loads with low input current requirements.

Features

• High Current Capability: Maximum collector current (I_C) of 500 mA.
• Low Voltage Operation: Maximum collector-emitter voltage (V_CEO) of 30 V.
• Very High DC Current Gain: Minimum current gain (h_FE) of 30,000, ensuring efficient signal amplification.
• Compact Package: TO-92 (SOT54) plastic package for easy PCB mounting and space-saving designs.
• Darlington Pair Configuration: Integrated two-transistor design for enhanced performance.
• Low Saturation Voltage: Ensures minimal power loss in switching applications.

Applications

The BC517 is widely used in applications requiring high current amplification and low input drive requirements. Typical use cases include:

• Signal Amplification: Audio pre-amplifiers, sensor interfaces, and other low-power signal conditioning circuits.
• Switching Loads: Relay drivers, LED drivers, and solenoid control circuits.
• Automotive Electronics: Dashboard displays, lighting controls, and other low-voltage automotive applications.
• Consumer Electronics: Remote controls, toys, and battery-operated devices.
• Industrial Control Systems: Motor drivers, actuator controls, and automation circuits.

Electrical Characteristics

The following tables summarize the key electrical specifications of the BC517 transistor under standard operating conditions (unless otherwise noted).

Absolute Maximum Ratings

• Collector-Emitter Voltage (V_CEO): 30 V
• Collector-Base Voltage (V_CBO): 30 V
• Emitter-Base Voltage (V_EBO): 5 V
• Collector Current (I_C): 500 mA (continuous)
• Total Power Dissipation (P_tot): 625 mW (at 25°C)
• Operating Junction Temperature (T_j): -55°C to +150°C

DC Current Gain (h_FE)

• Minimum h_FE: 30,000 (at I_C = 50 mA, V_CE = 2 V)
• Typical h_FE: 50,000 (under same conditions)

Saturation Characteristics

• Collector-Emitter Saturation Voltage (V_CE(sat)): 1.2 V (max) at I_C = 500 mA, I_B = 5 mA
• Base-Emitter Saturation Voltage (V_BE(sat)): 2.5 V (max) at same conditions

Frequency Response

• Transition Frequency (f_T): 50 MHz (typical)

Package Information

The BC517 is available in a TO-92 (SOT54) plastic package, which is a widely used through-hole package for low-power transistors. Key package details include:

• Package Type: TO-92 (SOT54)
• Mounting Style: Through-hole
• Pin Configuration:
  • Pin 1: Emitter (E)
  • Pin 2: Base (B)
  • Pin 3: Collector (C)
• Dimensions: Approximately 4.9 mm (L) x 3.9 mm (W) x 3.8 mm (H)
• Weight: ~0.35 grams
• Material: Molded plastic (epoxy)

Thermal Characteristics

• Thermal Resistance, Junction-to-Ambient (R_θJA): 200°C/W (typical)
• Thermal Resistance, Junction-to-Case (R_θJC): 83.3°C/W (typical)

Reliability and Compliance

The BC517 is designed to meet industry standards for reliability and performance. It is suitable for use in commercial and industrial environments. Key compliance and reliability notes include:

• RoHS Compliance: Lead-free and compliant with RoHS directives.
• Operating Life: Designed for long-term reliability under specified conditions.
• ESD Sensitivity: Standard handling precautions for ESD-sensitive devices should be followed.

Conclusion

The BC517 NPN Darlington transistor is a versatile and high-performance component suitable for a wide range of amplification and switching applications. Its extremely high current gain, compact package, and robust electrical characteristics make it an excellent choice for designers needing efficient signal amplification or load driving in space-constrained environments.