Part Number : MLL5221
Function : 2.4V, Zener Voltage Regulator Diode / 500mW
Package : DO-213AA Type
Maker : Microsemi Corporation
Pinouts : 
Description :
1N5221UR == MLL5221, 1N5821BUR == MLL5281B
The 1N5221BUR thru 1N5281BUR series of 0.5 watt Zener Voltage Regulators provides a surface mount equivalent to the popular JEDEC registered 1N5221B to 1N5281B for 2.4 to 200 volts in standard 5% tolerances as well as tighter tolerances identified by different suffix letters on the part number. These are also available with an internal-metallurgical-bond option by adding a “-1” suffix (see separate data sheet). Microsemi also offers numerous other Zener products to meet higher and lower power applications.
Official Site : http://www2.microsemi.com/existing-parts/parts/8060?catid=633
Datasheet PDF Download :
Others datasheet of same file : 1N5221,1N5222UR,1N5223UR,1N5225UR,1N5226UR