Onsemi 2N6039 NPN Darlington Transistor: Datasheet, Pinout, and Application Circuits
The Onsemi 2N6039 is a robust NPN Darlington power transistor designed for high-current, high-voltage switching applications. Housed in a TO-220 package, it is a fundamental component in power supply circuits, motor controllers, and industrial systems where substantial current amplification is required. Its Darlington pair configuration provides an exceptionally high DC current gain, allowing a small input current to control a much larger output current.
Datasheet Overview and Key Specifications
The 2N6039 is characterized by its ability to handle high voltages and currents, making it suitable for demanding environments. Key absolute maximum ratings from its datasheet include:
Collector-Emitter Voltage (VCE): 80 V
Collector Current (IC): 12 A (Continuous)
DC Current Gain (hFE): 750 (minimum at IC=6A, VCE=4V) - This high gain is the hallmark of the Darlington configuration.
Power Dissipation (PD): 75 W (at case temperature TC = 25°C)
These specifications highlight the transistor's core strength: switching significant power loads with minimal drive current. Engineers must consult the full datasheet for detailed information on derating curves, safe operating areas (SOA), and temperature dependencies to ensure reliable circuit design.
Pinout Configuration
The pinout for the TO-220 package is standard for many power transistors. When viewing the component from the front (the side with the metal tab and mounting hole):
Pin 1 (Left): Base
Pin 2 (Center): Collector (connected internally to the metal tab)
Pin 3 (Right): Emitter
It is critical to confirm this pinout with the manufacturer's datasheet for your specific supplier, as some alternative packages or manufacturers may have variations. Always use an insulating kit when mounting the metal tab to a heatsink, as the collector is electrically live.
Application Circuits
The primary function of the 2N6039 is as a low-side power switch. Here are two common application circuits:
1. Simple DC Motor Driver:
This circuit allows a microcontroller or logic gate (e.g., outputting 5V) to control a high-power 12V or 24V motor. The 2N6039 is placed between the motor and ground (low-side switching).
The microcontroller output pin is connected to the Base of the 2N6039 through a current-limiting resistor (e.g., 1kΩ).
The motor is connected between the positive supply (VMOTOR) and the Collector pin.
The Emitter pin is connected to ground.
A flyback diode (e.g., 1N4007) must be placed in reverse bias across the motor terminals (anode to collector, cathode to VMOTOR) to suppress voltage spikes generated when the motor is switched off, protecting the transistor.
2. Solid-State Relay (SSR) or Heater Controller:
The 2N6039 can be used to switch resistive loads like heaters or lamps. The circuit is similar to the motor driver but often includes a snubber network for highly inductive loads. An opto-isolator is highly recommended to provide electrical isolation between the low-voltage control circuit and the high-voltage power circuit, enhancing safety and noise immunity.
Design Considerations:
Heatsinking: Due to its 75W power dissipation capability, the 2N6039 requires an adequate heatsink for any application where significant power is handled. Without it, the device will overheat and fail prematurely.
Saturation Voltage: Darlingtons have a higher collector-emitter saturation voltage (VCE(sat)) than standard BJTs (typically around 1.5V for the 2N6039 at high current). This results in higher power loss and heat generation when the switch is fully on.
Switching Speed: The Darlington configuration has slower switching speeds compared to a single BJT or a MOSFET due to charge storage. It is ideal for low-frequency switching (up to several kHz) but not for high-frequency applications.
ICGOODFIND: The Onsemi 2N6039 remains a reliable and powerful choice for designers needing high-current amplification in linear and switching regulators, audio amplifiers, and various industrial control systems. Its high gain simplifies drive circuitry, though careful attention to heatsinking and voltage drop is essential for robust performance.
Keywords: NPN Darlington Transistor, High Current Gain, Power Switching, TO-220 Package, Motor Driver Circuit.
