Rainbow Electronics DS2781 - Manual (Page 21)

DS2781: Two-Cell Standalone Fuel Gauge IC
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USER EEPROM
A 16 byte User EEPROM memory (block 0, addresses 20h - 2Fh) provides non-volatile memory that is
uncommitted to other DS2781 functions. Accessing the User EEPROM block does not affect the operation of the
DS2781. User EEPROM is lockable, and once locked, write access is not allowed. The battery pack or host system
manufacturer can program lot codes, date codes and other manufacturing, warranty, or diagnostic information and
then lock it to safeguard the data. User EEPROM can also store parameters for charging to support different size
batteries in a host device as well as auxiliary model data such as time to full charge estimation parameters.
PARAMETER EEPROM
Model data for the cells, as well as application operating parameters are stored in the Parameter EEPROM
memory (block 1, addresses 60h - 7Fh). The ACR (MSB and LSB) and AS registers are automatically saved to
EEPROM when the RARC result crosses 4% boundaries. This allows the DS2781 to be located outside the
protection FETs. In this manner, if a protection device is triggered, the DS2781 cannot lose more that 4% of charge
or discharge data.