BQ27510-G2 Datasheet, PDF (29/38 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge With Direct Battery Connection

bq27510-G2
www.ti.com
SLUS948 – AUGUST 2010
RSNS1
0
0
0
0
1
1
1
1
Table 12. I_WAKE Threshold Settings⁽¹⁾
RSNS0
IWAKE
Vth(SRP-SRN)
0
0
Disabled
0
1
Disabled
1
0
+1. 25 mV or –1.25 mV
1
1
+2.5 mV or –2.5 mV
0
0
+2.5 mV or –2.5 mV
0
1
+5 mV or –5 mV
1
0
+5 mV or –5 mV
1
1
+10 mV or –10 mV
(1) The actual resistance value versus the setting of the sense resistor is not important; just the actual
voltage threshold when calculating the configuration. The voltage thresholds are typical values under
room temperature.
Flash Updates
Data Flash can only be updated if Voltage( ) ≥ Flash Update OK Voltage. Flash programming current can cause
an increase in LDO dropout. The value of Flash Update OK Voltage should be selected such that the
bq27510-G2 Vcc voltage does not fall below its minimum of 2.4V during Flash write operations.
AUTOCALIBRATION
The bq27510-G2 provides an autocalibration feature that will measure the voltage offset error across SRP and
SRN from time-to-time as operating conditions change. It subtracts the resulting offset error from normal sense
resistor voltage, VSR, for maximum measurement accuracy.
Autocalibration of the ADC begins on entry to SLEEP mode, except if Temperature( ) is ≤ 5°C or Temperature( )
= 45°C.
The fuel gauge also performs a single offset when (1) the condition of AverageCurrent( ) ≤ 100mA and (2)
{voltage change since last offset calibration ≥ 256mV} or {temperature change since last offset calibration is
greater than 8°C for ≥ 60s}.
Capacity and current measurements will continue at the last measured rate during the offset calibration when
these measurements cannot be performed. If the battery voltage drops more than 32mV during the offset
calibration, the load current has likely increased considerably; hence, the offset calibration will be aborted.
APPLICATION-SPECIFIC INFORMATION
BATTERY PROFILE STORAGE AND SELECTION
Common Profile Aspects
When a battery pack is removed from system equipment that implements the bq27510-G2, the fuel gauge
maintains some of the battery information, in case it is re-inserted. This way the Impedance Track™ algorithm
often has a means of recovering battery-status information, thereby maintaining good state-of-charge (SOC)
estimates.
Two default battery profiles are available to store battery information. They are used to provide the Impedance
Track™ algorithm with the default information on two possible battery types expected to be used with the
end-equipment. These default profiles can be used to support batteries of different chemistry, same chemistry
but different capacities, or same chemistry but different models. Default profiles are programmed by the
end-equipment manufacturer. Note that in the case of bq27510-G2, only one of the default profiles can be
selected, and this selection cannot be changed during end-equipment operation.
In addition to the default profiles, the bq27510-G2 maintains two active profiles: Cell0 and Cell1. These tables
hold dynamic battery data, and keep track of the status for up to two of the most recent batteries used. In most
cases the bq27510-G2 can administrate information on two removable battery packs.
Copyright © 2010, Texas Instruments Incorporated
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