DS2775 Datasheet, PDF (18/44 Pages) Maxim Integrated Products – 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication

2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with
Protector and Optional SHA-1 Authentication
VOLTAGE
(R)
TEMPERATURE
(R)
CURRENT
(R)
ACCUMULATED
CURRENT (ACR) (RW)
AVERAGE CURRENT
(R)
CELL MODEL PARAMETERS
(EEPROM)
AGING CAPACITY (AC)
(2 BYTES EE)
AGE SCALAR (AS)
(1-BYTE EE)
SENSE-RESISTOR PRIME (RSNSP)
(1-BYTE EE)
CHARGE VOLTAGE (VCHG)
(1-BYTE EE)
MINIMUM CHARGE CURRENT (IMIN)
(1-BYTE EE)
ACTIVE-EMPTY VOLTAGE (VAE)
(1-BYTE EE)
ACTIVE-EMPTY CURRENT (IAE)
(1-BYTE EE)
CAPACITY LOOKUP
AVAILABLE CAPACITY CALCULATION
ACR HOUSEKEEPING
AGE ESTIMATOR
LEARN FUNCTION
FULL
FULL(T) (R)
ACTIVE EMPTY AE(T)
(R)
STANDBY EMPTY SE(T)
(R)
REMAINING ACTIVE-ABSOLUTE
CAPACITY (RAAC) mAh
(R)
REMAINING STANDBY-ABSOLUTE
CAPACITY (RSAC) mAh
(R)
REMAINING ACTIVE-RELATIVE
CAPACITY (RARC) %
(R)
REMAINING STANDBY-RELATIVE
CAPACITY (RSRC) %
(R)
USER MEMORY (EEPROM)
16 BYTES
CYCLE COUNTER (EEPROM)
Figure 13. Top-Level Algorithm Diagram
Full
The full curve defines how the full point of a given cell
depends on temperature for a given charge termina-
tion. The application’s charge termination method
should be used to determine the table values. The
DS2775–DS2778 reconstruct the full line from cell char-
acteristic table values to determine the full capacity of
the battery at each temperature. Reconstruction occurs
in one-degree temperature increments.
Active Empty
The active-empty curve defines the variation of the
active-empty point over temperature. The active-empty
point is defined as the minimum voltage required for
system operation at a discharge rate based on a high-
level load current (one that is sustained during a high-
power operating mode). This load current is
programmed as the active-empty current (IAE), and
should be a 3.5s average value to correspond to values
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