BQ2084-V140_14 Datasheet, PDF (52/64 Pages) Texas Instruments – SBS v1.1-COMPLIANT GAS GAUGE FOR USE WITH THE bq29312

bq2084-V140
SLUS664B – JULY 2005 – REVISED AUGUST 2006
ADDITIONAL PROGRAMMING INFORMATION
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ADDITIONAL DATA FLASH PROGRAMMING
The following sections describe the function of each data flash location and how the data is to be stored.
Fundamental Parameters
Sense Resistor Value
The 32-bit CC Delta DF 0xcd-0xd0 corrects the coulomb counter for sense resistor variations. It represents the
gain factor for the coulomb counter. The 16-bit Sense Resistor Gain in DF 0xcb-0xcc scales each integrating
converter conversion to mAh. The Current() related measurement Sense Resistor Gain is based on the
resistance of the series sense resistor. The following formula computes a nominal or starting value for Sense
Resistor Gain from the sense resistor value (in Ω).
Sense Resistor Gain = 306.25/Rs
RSNS Value (mΩ)
5
10
20
Sense Resistor Gain
61250
30625
15312
CC offset
CC offset DF 0xd2-0xd3, contains the offset for the coulomb counter. It is automatically updated when the pack
has met the conditions for sleep, before it enters sleep mode.
DSC offset
DSC offset DF 0xd4, contains the offset for the pack ground reference. It is automatically updated when the
pack has met the conditions for sleep, before it enters sleep mode.
ADC offset
ADC offset DF 0xd5, contains the offset for the a/d converter. It is automatically updated when the pack has
met the conditions for sleep, before it enters sleep mode.
Digital Filter
The desired digital filter threshold, VDF (V), is set by the value stored in Digital Filter DF 0x2c.
Digital Filter = VDF / 290 nV
CELL AND PACK CHARACTERISTICS
Battery Pack Capacity and Voltage
Pack capacity in mAh units is stored in Design Capacity, DF 0x32-0x33. In mAh mode, the bq2084-V140 copies
Design Capacity to DesignCapacity(). In mWh mode, the bq2084-V140 multiplies Design Capacity by Design
Voltage DF 0x04-0x05 to calculate DesignCapacity() scaled to 10 mWh. Design Voltage is stored in mV.
The initial value for Full Charge Capacity, in mAh, is stored in DF 0x36-0x37. Full Charge Capacity is modified
over the course of pack usage to reflect cell aging under the particular use conditions. The bq2084-V140
updates Full Charge Capacity in mAh after a capacity learning cycle.
Remaining Time Alarm and Capacity Alarm
Remaining Time Alarm in DF 0x02-0x03 set the alarm thresholds used in the SMBus command codes 0x01 and
0x02, respectively. Remaining Time Alarm is stored in minutes and Remaining Capacity Alarm in units of mAh or
10 mWh, depending on the BatteryMode() setting.
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