BC557B,126

The BC557B,126 is a PNP general purpose bipolar junction transistor manufactured by NXP Semiconductors. It is designed for low-current switching and amplification applications, with a maximum collector current of 100mA and a maximum collector-emitter voltage of 45V. The transistor features a DC current gain (hFE) ranging from 220 to 475 at Vce=5V and Ic=2mA, and a transition frequency of at least 100MHz.

This device is housed in a TO-92-3 (TO-226AA) through-hole package with formed leads, making it suitable for breadboard prototyping and PCB insertion. The maximum power dissipation is 500mW at 25°C ambient temperature, with a junction-to-ambient thermal resistance of 250K/W when mounted on an FR4 board. The operating junction temperature range is up to 150°C, and storage temperature ranges from -65°C to 150°C.

Typical applications include general purpose switching and amplification circuits, such as signal conditioning, driver stages, and low-power audio amplification. The BC557B is the PNP complement to the NPN BC547B transistor, allowing complementary push-pull configurations. With its low saturation voltages (300mV max at Ic=100mA) and low noise figure (2dB typical), it is well-suited for small-signal analog circuits.

The transistor is available in a through-hole TO-92 package, which is widely used in hobbyist and industrial designs. It is RoHS3 compliant and has an MSL rating of 1 (unlimited floor life), simplifying handling and storage. The BC557B,126 is a reliable choice for engineers seeking a standard PNP transistor for general purpose use.