Part Number : MMBZ5221BLT1G
Marking : 18A
Function : 2.4V, Zener Voltage Regulators 225 mW
Package : SOT−23 Surface Mount
Maker : ON Semiconductor
Pinouts : 
Description :
This series of Zener diodes is offered in the convenient, surface mount plastic SOT−23 package. These devices are designed to provide voltage regulation with minimum space requirement. They are well suited for applications such as cellular phones, hand held portables,
Features
• 225 mW Rating on FR−4 or FR−5 Board
• Zener Voltage Range −2.4 V to 91 V
• Package Designed for Optimal Automated Board Assembly
• Small Package Size for High Density Applications
• ESD Rating of Class 3 (> 16 KV) per Human Body Model
Datasheet PDF Download : 
Others datasheet of same file :
MMBZ5221BLT3G, MMBZ5222BLT3G, MMBZ5223BLT3G,
MMBZ5224BLT3G, MMBZ5225BLT3G