BSS84WQ

Updated: 2026-09-13

Overview

The BSS84WQ is a P-channel enhancement mode MOSFET designed for low-voltage applications. As a surface-mount device in a compact SOT-23 package, it offers efficient power switching with minimal board space requirements. This component is particularly valued in battery-powered devices where energy efficiency is critical. Manufactured using advanced silicon technology, the BSS84WQ features a low gate threshold voltage (typically -1V to -2V), enabling operation with low control signals. Its design prioritizes low on-resistance (Rds(on)) to minimize power losses during conduction, making it ideal for power management circuits.

Structure and Working Principle

The BSS84WQ MOSFET consists of three terminals: Gate (G), Drain (D), and Source (S). When a negative voltage (relative to the source) is applied to the gate, it creates an inversion layer that allows current flow between drain and source. The component operates in enhancement mode, meaning no current flows at zero gate-source voltage. Internally, the device uses a vertical DMOS structure that provides excellent current handling capability relative to its small size. The gate oxide layer is precisely engineered to achieve the specified threshold voltage while maintaining reliability. Avalanche ruggedness is incorporated to withstand brief voltage spikes during switching operations.

Key Features

A standout feature of the BSS84WQ is its low threshold voltage, which enables operation with low-power control signals commonly found in portable electronics. The MOSFET offers a drain-source voltage (Vds) rating of -50V and continuous drain current (Id) of -130mA, suitable for many low-power applications. The component exhibits fast switching characteristics with typical rise and fall times in the nanosecond range. Its small SOT-23 package (2.9mm × 1.3mm × 1.1mm) makes it ideal for space-constrained designs. The device also features ESD protection, typically withstanding 2kV human body model discharges, enhancing reliability in real-world applications.

Application Areas

Primary applications include power management in portable electronics such as smartphones, tablets, and wearable devices. The BSS84WQ is commonly used for load switching, power gating, and battery protection circuits where efficient power control is required. In industrial contexts, this MOSFET finds use in low-power DC-DC converters, voltage regulators, and power distribution systems. Its characteristics make it suitable for interface circuits, signal switching, and as a replacement for small electromechanical relays. The automotive sector utilizes it in non-critical low-voltage systems where space and weight are considerations.

Maintenance and Precautions

While MOSFETs are generally maintenance-free, proper handling during assembly is crucial. Use ESD precautions when working with these devices, as the gate oxide is sensitive to static discharge. Soldering should follow recommended reflow profiles to prevent thermal damage to the package or die. In operation, ensure the maximum ratings for voltage, current, and power dissipation are not exceeded. Adequate PCB copper area should be allocated for heat dissipation, especially in continuous operation at higher currents. The device is not designed for linear mode operation near its maximum ratings - it should be used as a switch in either fully-on or fully-off states.

B2B Procurement Guide

When sourcing BSS84WQ MOSFETs, verify the manufacturer's authenticity as counterfeit components are common in the semiconductor market. Reputable distributors should provide traceability documentation. Consider purchasing from franchised distributors of major brands like Nexperia, ON Semiconductor, or Diodes Incorporated. For volume purchases (typically 1,000+ units), unit prices can decrease significantly. Lead times vary by manufacturer and market conditions - currently 8-12 weeks is common. Some suppliers offer tape-and-reel packaging for automated assembly. Request samples for testing before large orders, and confirm RoHS compliance if required for your application.