
DS2782: Stand-Alone Fuel Gauge IC 
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applications, Standby Empty represents the point that the battery can no longer support RAM refresh and thus the 
standby voltage is set by the RAM voltage supply requirements. In other applications, Standby Empty can 
represent the point that the battery can no longer support a subset of the full application operation, such as games 
or organizer functions on a wireless handset. The standby load current and voltage are used for determining the 
cell characteristics but are not programmed into the DS2782. The DS2782 reconstructs the Standby Empty line 
from cell characteristic table values to determine the Standby Empty capacity of the battery at each temperature. 
Reconstruction occurs in one-degree temperature increments. 
CELL MODEL CONSTRUCTION 
The model is constructed with all points normalized to the fully charged state at +40°C. Initial values, the +40°C 
Full value in mVh units and the +40°C Active Empty value as a fraction of the +40°C Full are stored in the cell 
parameter EEPROM block. Standby Empty at +40°C is by definition zero and therefore no storage is required. The 
slopes (derivatives) of the 4 segments for each model curve are also stored in the cell parameter EEPROM block. 
Segment endpoints are fixed at 0°C, +10°C, +20°C, +30°C and +40°C. An example of data stored in this manner is 
shown in Table 1. 
Table 1. Example Cell Characterization Table (Normalized to +40°C) 
Manufacturers rated cell capacity: 1000mAh 
Charge Voltage: 4.2V 
Charge Current: 500mA 
Active Empty (V, I): 3.0V, 300mA 
Standby Empty (V, I): 3.0V, 4mA 
Sense Resistor: 0.020  
+40 C 
Nominal 
[mAh] 
Full 
1051 
0.927 
0.951 
Active Empty 
0.051 
0.040 
Standby Empty 
0.013 
0.0067 
Figure 13. Lookup Function Diagram 
Termination Current: 50mA 
0°C 
+10°C 
+20°C 
+30°C 
+40°C 
0.974 
0.022 
0.0038 
0.991 
0.012 
0.001 
1.0 
0.008 
0 
APPLICATION PARAMETERS 
In addition to cell model characteristics, several application parameters are needed to detect the full and empty 
points, as well as calculate results in mAh units. 
Sense Resistor Prime (RSNSP):
 RSNSP stores the value of the sense resistor for use in computing the absolute 
capacity results. The value is stored as a 1-byte conductance value with units of mhos. RSNSP supports resistor 
values of 1  to 3.922m . RSNSP is located in the Parameter EEPROM block. 
Charge Voltage (VCHG):
 VCHG stores the charge voltage threshold used to detect a fully charged state. The 
value is stored as a 1-byte voltage with units of 19.52mV and can range from 0V to 4.978V. VCHG should be set 
marginally less than the cell voltage at the end of the charge cycle to ensure reliable charge termination detection. 
VCHG is located in the Parameter EEPROM block. 
Cell Model 
Parameters 
15 bytes 
(EEPROM) 
Temperature 
Lookup  
Function 
FULL(T) 
AE(T) 
SE(T)