Part of the Day · IRLML6402 — SOT-23 -20V P-channel MOSFET (marking E)

Part of the Day · 2026-10-31

A small P-channel MOSFET widely used to switch the supply (+) side on and off. It handles up to -3.7A in a SOT-23 package, and its on-resistance is specified with the gate pulled only -2.5V, so it often shows up as the power switch in battery-powered devices. Of the five characters on the chip, the first one, E, identifies this part number.

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 1 Gate (G) · 2 Source (S) · 3 Drain (D) — the side with a single lead is the drain

Package SOT-23 · Marking E

Key specifications

Values are from the Infineon (formerly International Rectifier) datasheet.

Marking and pins

Marking code E · Pins 1 Gate (G) · 2 Source (S) · 3 Drain (D) — the side with a single lead is the drain

Typical uses

• Power switch / load switch in battery-powered devices — source on the supply (+), turns on when the gate is pulled toward GND
• High-side switch that turns sensor or module power on and off separately in 3.3V/5V circuits (on-resistance ≤135mΩ even at VGS -2.5V)

Companion & similar parts

• IRLML2502 — N-channel companion in the same Micro3 (SOT-23) family — opposite polarity, not a substitute (marking code G)
• AO3400A — SOT-23 N-channel MOSFET covered earlier in Part of the Day — for GND-side switching

Five characters, XYWLC, are printed on the chip. X (the first character) is the part number code — E for IRLML6402 — Y is the year, W the week, L the assembly lot, and C marks copper wire / halogen-free (datasheet page 7). Because it is P-channel, all voltages and currents in the table are written as negative values. Even within SOT-23, pin order can differ between makers, so always check the datasheet pin diagram when substituting.