The SMC1990A1-F5 enhanced Silicon Serial Number is a low-cost, electronic registration number that provides an absolutely unique identity which can be detemined with a minimal electronic interface (typically,a single port pin of a microcontroller).The SMC1990 consists of a factory-lasered,64-bit ROM that includes a unique 48-bit serial number,an 8-bit CRC,and an 8-bit Family Code(01h). Data is transferred serially via the Smart-Wire protocol that requires only a single data lead and a ground return.Power for reading and writing the device id derived from the data line itself with no need for an extrnal power source.