Part of the Day · BZX84C5V1 — SOT-23 5.1V Zener diode (marking Z2)

Part of the Day · 2026-11-01

A 5.1V Zener diode (voltage regulator diode) in a small SOT-23 chip. With the pin 3 cathode on the high side, the pin 1 anode to GND and a series resistor, it clamps the voltage at about 5.1V, so it is widely used for simple voltage references and input protection. Pin 2 is not connected, and the chip is marked Z2 plus a one-letter manufacturing site code.

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 Anode (A) · 2 Not connected (n.c.) · 3 Cathode (K)

Package SOT-23 · Marking Z2

Key specifications

Values are from the Nexperia datasheet.

Marking and pins

Marking code Z2 · Pins 1 Anode (A) · 2 Not connected (n.c.) · 3 Cathode (K)

Typical uses

• Simple voltage reference — put it in series with one resistor to get about 5.1V (low-current circuits)
• Input protection — cathode to a 5V signal line, anode to GND, to clamp excess voltage
• General regulation functions (datasheet application)

Companion & similar parts

• BZX84-B5V1 — Same 5.1V with ±2% tolerance (marking code %R1)
• BZX84-A5V1 — ±1% tolerance version (5.04V ~ 5.16V, marking code %58)
• BZX84-C3V3 — 3.3V in the same series (marking code %B1)
• BZT52C5V1 — The same 5.1V in an SOD-123 package (Diodes and others)

Nexperia writes the part number with a hyphen, BZX84-C5V1, while other makers write BZX84C5V1. The table lists Z2%, and a one-letter manufacturing site code is printed in place of %. Other makers may use different marking codes for the same 5.1V part. The meaning of C (approx. ±5%) applies to the BZX84 series; in the 1N52xx and MMSZ52xx series the meanings of B and C are reversed.