BQ2063_15 Datasheet, PDF (44/60 Pages) Texas Instruments – SBS v1.1-COMPLIANT Li-ION GAS-GAUGE IC

bq2063
Not Recommended For New Designs
SBS v1.1ĆCOMPLIANT LiĆION GASĆGAUGE IC
WITH PROTECTOR INTERFACE
SLUS468E− MAY 2001 − REVISED APRIL 2002
PROGRAMMING INFORMATION
EEPROM programming
The following sections describes the function of each EEPROM location and how the data is to be stored.
fundamental parameters
sense resistor value
Two factors are used to scale the current related measurements. The 16-bit ADC Sense Resistor Gain value
in EE 0x68-0x69 scales Current( ) to mA. Adjusting ADC Sense Resistor Gain from its nominal value provides
a method to calibrate the current readings for system errors and the sense resistor value (Rs) . The nominal
value is set by
ADC
Sense
Resistor
Gain
+
625
(Rs)
(4)
The 16-bit VFC Sense Resistor Gain in EE 0x6a-0x6b scales each VFC interrupt to mAh. VFC Sense Resistor
Gain is based on the resistance of the series sense resistor. The following formula computes a nominal or
starting value for VFC Sense Resistor Gain from the sense resistor value.
VFC
Capital
Sense
Resistor
Gain
+
409.6
(Rs)
(5)
Sense resistor values are limited to the range of 0.00916 to 0.100Ω.
digital filter
The desired digital filter threshold, VDF (µV), is set by the value stored in Digital Filter EE 0x52.
Digital
Filter
+
2250
VDF
(6)
cell characteristics
battery pack capacity and voltage
Pack capacity in mAh units is stored in Pack Capacity, EE 0x3a-0x3b. In mAh mode, the bq2063 copies Pack
Capacity to DesignCapacity( ). In mWh mode, the bq2063 multiplies Pack Capacity by Design Voltage EE
0x12-0x13 to calculate DesignCapacity( ) scaled to 10 mWh. Design Voltage is stored in mV.
The initial value for Last Measured Discharge, in mAh, is stored in EE 0x38−0x39. Last Measured Discharge
is modified over the course of pack usage to reflect cell aging under the particular use conditions. The bq2063
updates Last Measured Discharge in mAh after a capacity learning cycle. The bq2063 uses the Last Measured
Discharge value to calculate FullChargeCapacity( ) in mAh or 10 mWh mode.
EDV thresholds and near full percentage
The bq2063 uses three pack voltage thresholds to provide voltage-based warnings of low battery capacity. The
bq2063 uses the values stored in EEPROM for the EDV0, EDV1, and EDV2 values or calculates the three
thresholds from a base value and the temperature, capacity, and rate adjustment factors stored in EEPROM.
If EDV compensation is disabled then EDV0, EDV1, and EDV2 are stored directly in mV in EE 0x72-0x73, EE
0x74-0x75, and EE 0x78-0x79, respectively.
For capacity correction at EDV2, Battery Low % EE 0x54 can be set at a desired state-of-charge,
STATEOFCHARGE%, in the range of 3-19%. Typical values for STATEOFCHARGE% are 5-7% representing
5-7% capacity.
Battery Low % = STATEOFCHARGE% • 2.56
(7)
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