BD140

The BD140 is a widely used medium-power PNP bipolar junction transistor (BJT) manufactured by ST. It is constructed using silicon technology and comes in a TO-126 package, making it suitable for various electronic circuits.

This transistor is valued for its balance of voltage capability, current handling, and stable linear performance. Key electrical specifications include a maximum collector current of -1.5 A, a collector-emitter voltage of -80 V, and a collector-base voltage of -80 V. It also has an emitter-base voltage rating of -5 V and a DC current gain (hFE) typically ranging from 25 to 250. The maximum power dissipation is 12.5 W, and it can operate at transition frequencies up to 190 MHz.

The BD140 is designed to handle moderate current and voltage levels. Its operating temperature range is from -55 °C to +150 °C. As part of a complementary transistor family, it is often paired with NPN devices like the BD139 and BD135, making it suitable for circuits requiring balanced or push-pull operation and stable linear performance.

Common applications for the BD140 include audio amplifiers, driver stages, and control circuits where reliability, symmetry, and predictable behavior are essential. Its TO-126 package is a common choice for medium-power applications.