Onsemi TIP147TTU PNP Darlington Transistor: Datasheet, Pinout, and Application Circuits
The Onsemi TIP147TTU is a high-power PNP Darlington transistor designed for robust switching and amplification tasks in demanding electronic applications. Its ability to handle high currents and voltages makes it a popular choice for power supplies, motor controllers, and audio amplifiers. This article provides a detailed overview of its datasheet specifications, pinout configuration, and practical application circuits.
Datasheet Overview and Key Specifications
The TIP147 is part of a complementary pair with the NPN TIP142. The "TTU" suffix indicates the package type (TO-220) and packing method (tube). Key absolute maximum ratings from its datasheet define its operational limits:
Collector-Emitter Voltage (VCEO): -100 V
Collector Current (IC): -10 A (continuous)
DC Current Gain (hFE): 1000 (min) at IC = -5 A, VCE = -4 V
Power Dissipation (PD): 125 W (at case temperature TC = 25°C)
A critical parameter for Darlington transistors is the low base drive requirement. Due to its high gain, the TIP147 can be switched on with a relatively small base current, making it easy to interface with microcontrollers or low-current driver ICs when used with an appropriate base resistor. However, designers must account for its higher saturation voltage (VCE(sat)), typically around -2 V at IC = -5 A, which results in more heat generation during conduction compared to a standard bipolar transistor.
Pinout Configuration
The TIP147TTU comes in the standard TO-220 package. When facing the flat side with the leads pointing downward, the pinout is as follows:
Pin 1 (Left): Base (B)
Pin 2 (Center): Collector (C)
Pin 3 (Right): Emitter (E)
It is imperative to correctly identify the pins before circuit assembly to prevent damage to the component or the circuit. The metal tab is internally connected to the collector pin, so it must be insulated from the heatsink unless the heatsink is at the collector potential.
Application Circuits
1. Simple DC Motor Speed Controller:
This transistor excels in motor control applications. A basic circuit involves connecting the motor between the positive supply rail and the TIP147's collector. The emitter is connected to ground. A potentiometer connected to the base via a current-limiting resistor (e.g., 1kΩ) allows for manual speed control by varying the base current. For bidirectional control, an H-bridge configuration can be built using complementary TIP14x pairs.
2. Linear Power Pass Element:
The TIP147 can serve as the series-pass transistor in a linear voltage regulator. In this setup, it controls the output voltage by dropping excess power from the input source. Its high current gain minimizes the load on the error amplifier IC (like a LM317), enabling the regulator to deliver several amps of stable output current. The transistor must be mounted on a substantial heatsink to dissipate the generated heat (Power = (Vin - Vout) Iload).
3. High-Power Audio Amplifier Output Stage:
In audio applications, the TIP147 is often used in the output stage of class AB amplifiers, paired with its NPN complement, the TIP142. This Darlington configuration provides the necessary current gain to drive loudspeakers with high power (50W - 100W), ensuring low distortion and good efficiency.
Conclusion and Design Considerations
The Onsemi TIP147TTU is a workhorse for high-power, low-frequency switching and amplification. Its primary advantages are its high current gain and robust voltage/current handling capabilities. Successful implementation requires careful attention to:
Heatsinking: This is non-negotiable. The device will quickly exceed its maximum junction temperature without a properly sized heatsink.
Saturation Voltage: Designers must account for the ~2V drop to ensure the load receives adequate voltage.
Flyback Protection: When driving inductive loads like motors or relays, a flyback diode must be used across the load to protect the transistor from voltage spikes.
ICGOODFIND: For engineers and procurement specialists, the Onsemi TIP147TTU represents a reliable and widely available solution for high-power amplification and control. Its Darlington structure simplifies driver circuit design, making it an excellent choice for industrial and automotive systems where rugged performance is required.
Keywords: PNP Darlington Transistor, High Power Amplification, Motor Control Circuit, TO-220 Package, Onsemi TIP147
