The DS3802 battery cap is a snap-on lithium power source for Dallas Semiconductor's 40mm BGA NV SRAM modules including the DS3832C-311 and DS3816C-511. After a host BGA module has been soldered in place and cleaned, the DS3802 battery cap is snapped onto the module to serve as the secondary power supply. The battery cap is keyed to prevent incorrect attachment and is designed to maintain mechanical and electrical contact with its host module even during severe shock and vibration. Electrically, the DS3802 battery is connected to the host BGA module with gold-plated round pins in the battery cap inserted into gold-plated receptacles on the BGA. Mechanically, two flanges on the DS3802 tightly grip the BGA module board to prevent accidental cap removal, while corner features in the cap prevent lateral movement of the cap while it is attached to its host BGA module. 1 of 2