Infineon BSS127H6327XTSA2 N-Channel MOSFET: Datasheet, Application Circuit, and Replacement Guide

The Infineon BSS127H6327XTSA2 is a popular N-Channel enhancement mode MOSFET utilizing Infineon's advanced small-signal MOSFET technology. Encased in a compact SOT-23 (TO-236AB) surface-mount package, this device is engineered for high efficiency and reliability in low-voltage, low-current applications. Its primary appeal lies in its ability to provide excellent switching performance with minimal drive requirements.

Key Datasheet Parameters and Characteristics

Understanding the critical parameters from the datasheet is essential for effective circuit design:

Drain-Source Voltage (V_DS): 200V. This high voltage rating makes it suitable for off-line switchers and other high-voltage circuits.

Continuous Drain Current (I_D): 130 mA. It is designed for small-signal amplification and switching.

On-Resistance (R_DS(on)): 35 Ω (max. at V_GS = 10V, I_D = 50 mA). This value determines the power loss and voltage drop when the MOSFET is fully turned on.

Gate Threshold Voltage (V_GS(th)): 1.7V - 3.0V. This low threshold voltage allows it to be easily driven by logic-level signals from microcontrollers (e.g., 3.3V or 5V).

Package: SOT-23. This miniature package is ideal for space-constrained PCB designs.

Typical Application Circuit

A common use case for the BSS127 is as a low-side switch controlled by a microcontroller (MCU). This configuration is fundamental for driving relays, LEDs, or small motors.

Circuit Operation:

1. MCU Output LOW (0V): When the GPIO pin of the MCU is set to logic low, the voltage at the gate (G) is 0V. The MOSFET is in its cut-off region, and no current flows from the drain (D) to the source (S). The load is off.

2. MCU Output HIGH (3.3V/5V): When the MCU pin is set to logic high, the gate voltage rises above the MOSFET's threshold voltage. The device enters the saturation region, creating a low-resistance path between drain and source. Current flows through the load, turning it on.

The pull-down resistor (R1, e.g., 10kΩ) is crucial. It ensures the gate is pulled to ground when the MCU pin is in a high-impedance state (e.g., during startup or reset), preventing false triggering and keeping the MOSFET firmly off.

Replacement and Cross-Reference Guide

When the BSS127 is unavailable, selecting a suitable replacement requires careful comparison of key specifications. Potential alternatives include:

ON Semiconductor 2N7002K: A very common logic-level MOSFET with similar V_DS (60V) and higher I_D (300 mA). Check if the voltage rating is sufficient for your application.

Diodes Incorporated DMN3404L: Features a low R_DS(on) and is designed for low-voltage load switching.

Vishay Si2302CDS: Another strong SOT-23 competitor with logic-level compatibility.

Before substituting, always verify:

1. Voltage Ratings (V_DS, V_GS): Must meet or exceed the original requirements.

2. Current Handling (I_D): Must be sufficient for the load current.

3. Gate Threshold Voltage (V_GS(th)): Must be compatible with your drive circuitry (e.g., 3.3V MCU).

4. Package and Pinout (SOT-23): Must be identical for a drop-in replacement.

ICGOODFIND: The Infineon BSS127H6327XTSA2 is a highly versatile N-Channel MOSFET prized for its high voltage capability and logic-level gate control. It is an optimal choice for designers needing a reliable switch for low-power, high-voltage applications. Successfully implementing or replacing it hinges on a thorough review of the datasheet, particularly its voltage, current, and threshold characteristics, to ensure seamless integration into your electronic designs.

Keywords: N-Channel MOSFET, Logic-Level Gate, SOT-23 Package, High Voltage Switching, Low On-Resistance