MM3Z18VB

MM3Z18VB is a fixed 18-volt Zener diode in the SMT MM3Z family. It is used to clamp or regulate voltage in low-power circuits, providing simple over-voltage protection or a reference in a shunt regulator.
How it works:
- It is reverse-biased and conducts when the node reaches approximately 18 V, holding the voltage close to that level.
Key points:
- Package: surface-mount (exact footprint varies by manufacturer; check the datasheet).
- Vz: nominal about 18 V (tolerance and tempco vary by vendor).
- Power and current ratings: dependent on the specific vendor’s variant (Pz, Izt, leakage, etc.).
Typical applications:
- Power-supply rail clamping, input protection, and basic voltage reference in compact, low-power designs.
Design notes:
- Ensure the current through the diode stays within its power rating.
- For exact values (tolerance, Izt, Pd, leakage), consult the specific MM3Z18VB datasheet from the component vendor.

Do you mean the MM3Z18VB transient-voltage-suppression (TVS) diode? Which parameters matter for your application — package (SOD-123, SMB, DO-214), unidirectional vs bidirectional, standoff (18 V), and power rating? Tell me those and I’ll list exact drop-in equivalents.

- Pin count: 3 pins (SOT-23 package)
- Function: Three-terminal Zener diode (18 V nominal) used as a voltage clamp/reference/shunt regulator for low-power protection or regulation.

Manufacturer: ON Semiconductor (ON Semi).
What kind of company: A global American semiconductor company that designs and manufactures energy-efficient discrete components and integrated circuits for automotive, industrial, computing, and consumer markets.

MM3Z18VB is a transient voltage suppressor (TVS) / Zener diode rated for about 18V. Typical applications:
- Protection of 12–24V automotive and industrial power rails from surges and transients
- Input/output protection for DC‑DC converters and voltage regulators
- Protection of external connectors, cables, and power lines against surges/ESD
- Gate/clamp protection for MOSFETs and switching devices in 18V systems
- General overvoltage clamping on 18V-class supply rails in telecom/consumer electronics

Which manufacturer or datasheet do you mean? MM3Z18VB is a TVS diode and vendors may offer different package options (commonly SOD‑523 or SOD‑123/SC‑70). Provide the vendor or a datasheet link and I’ll confirm the exact package.