TIP147 PNP Power Darlington Transistor (TO-247)

Prototyping and Engineering Tips from Robogears

• The PNP Switching Logic: Remember that as a PNP transistor, the TIP147 is typically used as a "High-Side Switch." To turn the load ON, the base must be pulled to a lower voltage relative to the emitter.

• Heatsinking is Mandatory: When dissipating power near its 125W limit, the TO-247 package will become extremely hot. Always use a generous amount of thermal paste and a high-fin-density aluminum heatsink. If the transistor exceeds $25^{\circ}C$ ambient, you must derate the power handling according to the datasheet curves.

• Base Resistor Calculation: Even though it has high gain, always use a base resistor (typically $220\Omega$ to $1k\Omega$) to limit the current coming from your control source (e.g., Arduino or PLC).

• Inductive Load Protection: While the Darlington pair has an internal diode, for heavy inductive loads like large motors, we still recommend adding an external high-speed "Flyback" diode (like the MUR1560) across the load for maximum circuit longevity.

Package Includes

• 1 x TIP147 PNP High-Power Darlington Transistor (TO-247)

Disclaimer

This is a high-power semiconductor. Always ensure your power supply and wiring can handle the intended current (up to 10A) to prevent electrical fires. Avoid touching the heatsink or the transistor body while the circuit is under high load.