Part of the Day · BSS84 — SOT-23 -50V P-channel small-signal MOSFET (marking 13)

Part of the Day · 2026-11-06

A SOT-23 P-channel MOSFET used to switch small signals on and off. It withstands up to -50V, but its current is only about -130mA, so it is a logic/signal switch rather than a power part, and it often appears alongside the N-channel BSS138 as its counterpart. The chip is printed with 13 plus one production-site character.

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 13

Key specifications

Values are from the Nexperia (formerly NXP) datasheet.

Marking and pins

Marking code 13 · Pins 1 Gate (G) · 2 Source (S) · 3 Drain (D) — the side with a single lead is the drain

Typical uses

• High-side switch that turns small loads (LEDs, sensor power, etc.) on and off from the supply (+) side in 3.3V/5V logic circuits
• Signal switch driven directly from CMOS/TTL outputs; relay and small transformer drivers (applications listed in the datasheet)

Companion & similar parts

• BSS138 — SOT-23 N-channel MOSFET covered earlier in Part of the Day — opposite polarity, not a substitute; its GND-side counterpart
• IRLML6402 — Also a SOT-23 P-channel, but a -20V / -3.7A power part — voltage range differs, so check before substituting

The chip marking is 13*. The * position is a production-site character: - or p = Hong Kong, t = Malaysia, W = China (datasheet section 4, Marking). The halogen-free version BSS84/DG is marked ZV*. Because it is P-channel, all voltages and currents in the table are written as negative values. BSS84 parts from other makers may use different marking codes, so check that maker's datasheet Marking table.