BC549

Single Bipolar Transistors Overview

The BC549 is an NPN epitaxial silicon transistor designed for switching and low-noise amplifier applications. It features a collector-emitter voltage (VCEO) of 30 V, a collector-base voltage (VCBO) of 30 V, and an emitter-base voltage (VEBO) of 5 V. The device supports a continuous DC collector current of 100 mA with a power dissipation rating of 500 mW. Key electrical characteristics include a DC current gain (hFE) ranging from 110 to 800 depending on the classification, a transition frequency (fT) of 300 MHz at IC = 10 mA, and a noise figure as low as 1.2 dB. The component is housed in a TO-92 package.

Single Bipolar Transistors Feature Summary

• Low-noise performance suitable for sensitive signal amplification
• High DC current gain across multiple classification grades
• Complementary pairing available with BC559 PNP transistor

Single Bipolar Transistors Applications

• General-purpose low-noise audio amplification
• Signal processing circuits requiring high input impedance
• Switching applications within specified voltage limits

Single Bipolar Transistors Procurement Notes

Verify the specific ordering suffix (e.g., BTA, BTF, CBU) to confirm the packing method, such as bulk or tape and reel, as these affect handling procedures. Ensure the hFE classification (A, B, or C) matches the circuit requirements for current gain tolerance. Confirm that the part number reflects the updated nomenclature without underscores, consistent with ON Semiconductor integration standards. Validate authenticity through authorized distributors to avoid counterfeit components.

Single Bipolar Transistors Selection Notes

Select the BC549 when low noise figures are critical, distinguishing it from the higher-voltage but noisier BC546/547/548 variants. Choose the appropriate hFE bin (B or C) based on the required gain stability for the amplifier stage. Ensure the application voltage does not exceed the 30 V collector-emitter limit. Consider the complementary BC559 for push-pull configurations. Verify thermal management capabilities given the 500 mW dissipation rating in the TO-92 package.

Single Bipolar Transistors Part Context

The BC549 belongs to a family of NPN epitaxial silicon transistors including the BC546 through BC550 series. While sharing similar physical packaging and basic switching capabilities, the BC549 is specifically optimized for low-noise operations compared to its counterparts. It serves as the NPN complement to the BC559 PNP transistor. The series was originally manufactured by Fairchild Semiconductor and is now managed under ON Semiconductor following corporate integration.

Single Bipolar Transistors Replacement Considerations

Direct functional substitutes within the same low-noise specification include the BC550. For general switching applications where noise is less critical, the BC547 or BC548 may be used if voltage ratings align. Always verify pinout compatibility and hFE classifications when substituting.