Category: Bi-polar Transistor (BJT)

Introduction The BD439 is a medium-power NPN silicon transistor, designed for both switching and linear amplifier applications. It belongs to a family of plastic-package power transistors (e.g. BD439, BD441) used widely in audio, power supply, and driver circuits. The BD439 is suited for designs where moderate currents and voltages are present and where symmetrical or […]

Introduction The BD438 is a medium-power PNP silicon transistor intended for linear amplification and switching applications. It is part of the BD43x complementary transistor family from ST / ON Semiconductor, serving as the PNP counterpart to the NPN device BD437. This transistor is packaged in a SOT-32 / TO-126 plastic case, which supports modest heatsinking […]

Introduction The BD437 is a medium-power NPN silicon transistor designed for both switching and linear amplifier applications. It is part of the STMicroelectronics BD43x series of complementary power transistors. ST describes it as a silicon epitaxial-base NPN transistor in JEDEC SOT-32 plastic packaging, intended for medium power linear and switching use. Because it belongs to […]

Introduction The BD436 is a PNP epitaxial-base medium-power silicon transistor engineered for linear amplification and switching applications. It is part of the same transistor family as BD434 and BD438, and is designed to be the PNP complement to NPN devices such as BD435. Housed in the TO-126 (JEDEC SOT-32) plastic package, BD436 offers a compact […]

Introduction The BD435 is a silicon epitaxial-base NPN power transistor intended for medium-power switching and linear amplifier applications. It belongs to the same transistor family as BD433 and BD437, packaged in a JEDEC SOT-32 / TO-126 plastic case, which is suited for modest heatsinking and robust mounting in amplifier or power circuits. Designed as a […]

Introduction The BD434 is a silicon epitaxial-base PNP medium-power transistor engineered for linear amplification and switching applications. It belongs to a complementary pairing family, designed to work alongside NPN devices like BD433 in push-pull and audio output stages. Its PNP polarity enables it to handle negative-half cycles or high-side switching in amplifier circuits. This transistor […]

Introduction The BD433 is a silicon epitaxial-base NPN power transistor designed for medium-power linear and switching applications. It is packaged in a JEDEC SOT-32 / TO-126 plastic outline, making it suitable for mounting on small heatsinks while still offering moderate power capability. It is commonly used in audio output stages, radio amplifiers, and general-purpose power […]

Introduction The BD244 (and its variants BD244A / BD244B / BD244C) is a PNP epitaxial-base power transistor intended for medium-power linear amplification and switching applications. It is widely used in circuits where PNP polarity is required such as in high-side switches, complementary amplifier stages, and push-pull output configurations. The transistor’s design combines sufficient voltage tolerance, […]

Introduction The BD243 (and its variants BD243A, BD243B, BD243C) is a silicon epitaxial-base NPN power transistor intended for medium-power switching and linear amplification applications. It is built to handle higher voltage and current stresses, making it suitable in amplifier output stages, power supplies, and driver circuits where robustness is required. The transistor is packaged in […]

Introduction The BD242 is a PNP epitaxial-base power transistor designed for medium power switching and linear amplification applications. It belongs to the BD241/BD242 complementary transistor family, where BD242 serves as the PNP counterpart to BD241. With multiple variants (BD242, BD242A, BD242B, BD242C) offering varying voltage ratings, this transistor affords flexibility to designers working with different […]