Patent ID: 6961592

Claim:
A protection circuit ( 10 ) for a battery ( 14 ) used with a cellular telephone, the protection circuit comprising: a first memory ( 28 ) storing first data which identifies the battery; a second memory ( 32 ) for storing second data associated with the telephone and which identifies a battery which is permitted to be used with the telephone; a first software driven controller ( 26 ) for comparing the first data to said second data; and a switch responsive to the controller ( 38 ) for connecting the battery to the telephone; wherein the protection circuit ( 110 ) is encapsulated in an insulating material, is provided in combination, as an integral unit with the battery ( 14 ) and is electrically connected to the battery ( 14 ) by means of a thermal fuse ( 16 ), wherein the first controller ( 26 ) causes the switch to connect the battery to the telephone only if the first data corresponds to the second data.