DS2782G-5+T&R Maxim Integrated Products, DS2782G-5+T&R Datasheet - Page 14

• Manufacturer Part Number: DS2782G-5+T&R
• Description: IC FUEL GAUGE STND-ALONE 10-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of DS2782G-5+T&R

• Function: Fuel, Gas Gauge/Monitor
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 2.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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
Active Empty (V, I): 3.0V, 300mA
Sense Resistor: 0.020
Full
Active Empty
Standby Empty
Figure 13. Lookup Function Diagram
Temperature
Parameters
(EEPROM)
Cell Model
15 bytes
+40C
Nominal
[mAh]
1051
Charge Current: 500mA
0.927
0.051
0.013
0°C
Function
Lookup
0.0067
+10°C
0.951
0.040
Standby Empty (V, I): 3.0V, 4mA
14 of 28
0.0038
Termination Current: 50mA
+20°C
0.974
0.022
FULL(T)
SE(T)
AE(T)
+30°C
0.991
0.012
0.001
+40°C
0.008
1.0
0