isl6295 Intersil Corporation, isl6295 Datasheet - Page 24

• Manufacturer Part Number: isl6295
• Description: Low Voltage Fuel Gauge
• Manufacturer: Intersil Corporation

Fuel Gauge Operation
The operation overview diagram in Figure 9 illustrates the
fuel gauge operation of the ISL6295. The ISL6295
incorporates four 32-bit accumulators and four 32-bit
elapsed time counters. The Charge Current Accumulator
(CCA) and Discharge Current Accumulator (DCA)
Input
ISL6295 IC
Host
(Charge Current
Charge Current
Accumulator)
CCA
24
(Charge Time
Capacity Calculation
NOTES:
Counter)
CTC
Gross_Capacity (mAh) = (Delta_Capacity_Count *
SelfDischarge_Loss (mAh) = SelfDischarge_LookupTable
Adjusted_Capacity = Gross_Capacity - SelfDischarge_Loss
Delta_Capacity_Count = CCA - DCA
Delta_Time_Count = CTC + DTC
1. 130µAs is the Accumulator LSB based upon 20mΩ sensor
2. The length of CCA, DCA, CTC, and DTC are 32-bit long;
3. CCA, DCA, CTC, and DTC will be updated every 0.5 second;
[ItCtrl/EtCtrl] * ((Delta_Time_Count * 0.5)/3600)
resistor and 15-bit resolution;
FIGURE 9. FUEL GAUGE OPERATION
(Discharge Current
Discharge Current
Accumulator)
DCA
130µAs) / (1000 * 3600)
ISL6295
Time Counter)
(Discharge
accumulate a measure of charge and discharge currents for
the capacity calculation and cycle count. The Charge Time
Counter (CTC) and Discharge Time Counter (DTC) are
intended to maintain the total charge time and discharge
time for the self-discharge, average charge, and discharge
currents over an extended period of time.
DTC
(Voltage ADC)
Voltage
VPCtrl
(Temperature ADC)
Temperature
ItCtrl/EtCtrl
November 10, 2005
FN9074.1