BF545B,215

Overview

The BF545B is an N-channel symmetrical silicon junction field-effect transistor housed in a SOT23 plastic surface-mounted package. It features a drain-source voltage rating of ±30 V and a total power dissipation of 250 mW at 25 °C ambient temperature. The device exhibits a forward transfer admittance (|yfs|) ranging from 3 to 6.5 mS under standard test conditions. For the BF545B variant, the gate-source cut-off voltage (VGSoff) spans from -1.6 V to -3.8 V, while the drain current (IDSS) ranges between 6 mA and 15 mA.

Feature Summary

• Low leakage level with typical values around 500 fA
• High gain characteristics suitable for amplification applications
• Designed for broadband operation with excellent thermal stability

Applications

• Impedance converters in electret microphones
• Impedance converters in infra-red detectors
• VHF amplifiers in oscillators and mixers

Procurement Notes

Verify the specific part marking code '21*' on the component body to confirm it corresponds to the BF545B type number rather than the BF545A or BF545C variants. Ensure that handling procedures account for ElectroStatic Discharge (ESD) sensitivity during transport and assembly. Confirm the package version matches the required SOT23 footprint specifications for your printed-circuit board design.

Selection Notes

Select the BF545B when a moderate drain current range of 6 mA to 15 mA is required compared to the lower currents of the BF545A. This variant offers a gate-source cut-off voltage range of -1.6 V to -3.8 V, providing different biasing flexibility than the other series members. Consider the symmetrical structure and low leakage for high-impedance input stages where signal integrity is critical.

Part Context

This component belongs to the BF545A/B/C family of N-channel silicon junction field-effect transistors manufactured by NXP Semiconductors. All three variants share identical pinning configurations and general package dimensions but differ in their electrical parameters, specifically regarding drain current and cut-off voltage thresholds. They are designed as complementary devices for various analog and RF circuit applications.

Replacement Considerations

Public confirmed substitute part numbers: None identified in verified documentation.