BF556A,235

Overview

The BF556A 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|) of at least 4.5 mS under standard test conditions. Specific electrical characteristics include a gate-source cut-off voltage range of -0.5 V to -7.5 V and a typical drain current (IDSS) of 3 mA to 7 mA.

Feature Summary

• Low leakage level with typical values around 500 fA
• High gain performance suitable for signal amplification
• Low cut-off voltage enabling efficient control

Applications

• Impedance converters for electret microphones
• Impedance converters for infrared detectors
• VHF amplifiers in oscillators
• VHF amplifiers in mixers

Procurement Notes

Verify the specific ordering suffix against the manufacturer's official documentation, as markings indicate regional manufacturing origins such as Hong Kong, Malaysia, or China. Confirm that the component status aligns with project requirements, noting that availability may vary due to production lifecycle stages. Ensure ESD precautions are strictly followed during handling and transport to prevent damage to the sensitive silicon junction.

Selection Notes

Select the BF556A when low input impedance conversion is required for high-impedance sensors like electret microphones or infrared detectors. The device is appropriate for VHF frequency applications in oscillators and mixers where low cut-off voltage and high gain are critical. Evaluate thermal resistance and power dissipation limits relative to the PCB mounting pad size to ensure reliable operation within the specified temperature range.

Part Context

This component belongs to the BF556 series of N-channel silicon junction field-effect transistors, which also includes the BF556B and BF556C variants. These devices share the same SOT23 package and general structural description but differ in their specific drain current and cut-off voltage parameters. The series is designed for general-purpose analog switching and amplification tasks requiring symmetrical characteristics.

Replacement Considerations

Direct substitutes within the same family include BF556B and BF556C. Verify parameter compatibility, specifically drain current (IDSS) and gate-source cut-off voltage (VGSoff), as these values differ between the A, B, and C variants. Ensure the replacement part meets the required impedance conversion and VHF amplification specifications for the target application.

FAQ

What is the pin configuration for the BF556A in the SOT23 package?

Pin 1 is the source, Pin 2 is the drain, and Pin 3 is the gate.

How does the BF556A differ from the BF556B?

The primary difference lies in the drain current (IDSS) and gate-source cut-off voltage ranges; the BF556A has a lower typical IDSS (3-7 mA) compared to the BF556B (6-13 mA).

Is the BF556A suitable for automotive applications?

No, unless explicitly stated otherwise in the data sheet, this product is not automotive qualified and should not be used in automotive equipment without customer risk assessment.