Part of the Day · AO3400A — SOT-23 30V N-channel MOSFET

Part of the Day · 2026-10-23

A small N-channel MOSFET that turns on with only 2.5V on the gate. It handles up to 5.7A in a SOT-23 package, so it is widely used as a switch driven directly from a microcontroller pin to turn LEDs, motors and relays on and off.

Actual size

↓ Actual size, left edge aligned to 0 on the ruler

One ruler tick = 1mm. On PC this is actual size on a 24-inch FHD monitor at 100% zoom; on iPhone it adjusts automatically. For other screens, use “Calibrate ruler” below.

Enlarged (SOT-23 · top view · approx. 20×)

Pins G Gate · S Source · D Drain — the side with a single lead is the drain (D); the two leads on the opposite side are the gate (G) and source (S)

Package SOT-23

Key specifications

Values are from the Alpha & Omega Semiconductor (AOS) datasheet.

Marking and pins

Typical uses

• Load switch driven directly from a 3.3V/5V microcontroller pin (on-resistance ≤48mΩ even at VGS 2.5V)
• Low-side switch turning LEDs, motors, relays and solenoids on and off on the GND side, PWM control

Companion & similar parts

• AO3401A — SOT-23 P-channel companion from the same maker — used as a switch on the supply (+) side
• 2N7002 — Smaller SOT-23 N-channel for signal use (a few hundred mA class)

The AOS datasheet drawing shows only the D, G and S positions, without pin numbers. SOT-23 MOSFETs from other makers may have a different pin order, so always check that maker's datasheet pin diagram when substituting. RDS(on) in the table is the datasheet table value (max); actual heating depends on the PCB copper area.