Infineon BSS138NH6327XTSA2 N-Channel Logic Level MOSFET: Datasheet, Pinout, and Application Circuits

The Infineon BSS138NH6327XTSA2 is a widely adopted N-Channel Logic Level Enhancement Mode MOSFET housed in a compact SOT-23 surface-mount package. Renowned for its efficiency in low-voltage scenarios, this MOSFET is a cornerstone component for power management and switching applications in modern electronics.

Engineered with advanced trench technology, its primary appeal lies in its ability to be driven directly from logic-level signals (as low as 1.8V or 3.3V), eliminating the need for a separate driver IC in many cases. This makes it exceptionally useful for interfacing between microcontrollers, like those found on Arduino or Raspberry Pi boards, and higher-power loads such as motors, LEDs, or relays.

Key Datasheet Specifications

A thorough review of the datasheet reveals the critical parameters that define this component's performance:

Drain-Source Voltage (V_DS): 50 V – Suitable for a wide range of low-power applications.

Continuous Drain Current (I_D): 220 mA – Defines its current-carrying capability.

On-Resistance (R_DS(on)): A remarkably low 3.5 Ω (max) at V_GS = 4.5 V and 1.5 Ω (max) at V_GS = 10 V. This low resistance minimizes power loss and heat generation when the switch is on.

Gate Threshold Voltage (V_GS(th)): Between 0.5 V and 1.5 V – This low threshold is what qualifies it as a "logic-level" MOSFET, ensuring full enhancement with microcontroller GPIO pins.

Package: SOT-23 (SC-59) – An ultra-small-footprint package ideal for space-constrained PCB designs.

Pinout Configuration

The pinout for the SOT-23 package is standard for this type of transistor. When viewing the component with the flat side facing you and leads pointing downward:

Pin 1 (Left): Gate (G) – The control pin. Voltage applied here relative to the Source turns the MOSFET on or off.

Pin 2 (Middle): Drain (D) – The output pin connected to the load.

Pin 3 (Right): Source (S) – Typically connected to ground.

Application Circuits

Two fundamental circuits demonstrate the BSS138NH6327XTSA2's utility:

1. Low-Side Switch Configuration: This is the most common application. The load (e.g., an LED) is placed between the positive supply rail and the Drain (D) pin. The Source (S) is connected directly to ground. The microcontroller's GPIO pin is connected to the Gate (G), often through a small series resistor (e.g., 100Ω) to dampen any ringing. A pull-down resistor (e.g., 10kΩ) from the Gate to ground ensures the MOSFET turns off fully when the GPIO is in a high-impedance state. When the GPIO outputs a logic HIGH (3.3V), the MOSFET turns on, completing the circuit and powering the load.

2. Logic Level Converter: A pair of BSS138s can create a simple bidirectional level shifter, crucial for interfacing a 3.3V device with a 5V one. The MOSFET's inherent properties allow a signal to be pulled up to a higher voltage (HV) on one side while being controlled by a lower voltage (LV) on the other, protecting the lower-voltage IC from damage.

ICGOODFIND

The Infineon BSS138NH6327XTSA2 stands out as an industry-standard, logic-level MOSFET due to its exceptional balance of low threshold voltage, low on-resistance, and compact form factor. Its reliability and cost-effectiveness make it a default choice for designers for countless low-power switching tasks, from consumer electronics to embedded systems prototyping.

Keywords:

1. Logic Level MOSFET

2. Low On-Resistance (RDS(on))

3. SOT-23 Package

4. Low-Side Switching

5. Gate Threshold Voltage