2N5551

The 2N5551 is an NPN silicon bipolar junction transistor designed for general-purpose amplifier and switching applications. Manufactured by ON Semiconductor, this device offers a maximum collector-emitter voltage (VCEO) of 160V and a continuous collector current rating of 600mA, making it suitable for medium-voltage, moderate-current circuits.

Key electrical characteristics include a DC current gain (hFE) of 80 minimum at 10mA collector current and 5V VCE, with a gain bandwidth product of 300 MHz. The collector-emitter saturation voltage is typically 0.20V at 50mA collector current and 5mA base current, ensuring low on-state losses. The device is rated for a junction temperature range of -55°C to 150°C, with a maximum power dissipation of 625mW at 25°C ambient (derate 5mW/°C above 25°C) and 1.5W at case temperature 25°C (derate 12mW/°C).

The 2N5551 is housed in a TO-92 (TO-226) through-hole package, which is widely used for low-power discrete transistors. The package is compatible with standard PCB layouts and is suitable for manual or automated assembly. Thermal resistance is 200°C/W junction-to-ambient and 83.3°C/W junction-to-case.

This transistor is commonly used in driver stages, signal amplification, and switching circuits where moderate voltage and current handling are required. Its high voltage rating relative to typical small-signal transistors makes it a popular choice for applications such as telephone line interfaces, relay drivers, and audio preamplifiers.