BQ27505-J2 Datasheet, PDF (29/42 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge

bq27505-J2
www.ti.com
System-Side Impedance Track™ Fuel Gauge
SLUS924 – APRIL 2009
Figure 5-1 details how the BAT_GD pin functions in the context of battery insertion and removal, as well
as NORMAL vs. SLEEP modes.
In PFC 1, the BAT_GD pin is also used to disable battery charging when the bq27505 reads battery
temperatures outside the range defined by [Charge Inhibit Temp Low, Charge Inhibit Temp High]. The
BAT_GD line is asserted once temperature falls within the range [Charge Inhibit Temp Low + Temp
Hys, Charge Inhibit Temp High – Temp Hys].
5.3.5 Battery Detection Using the BI/TOUT Pin
During power-up or hibernate activities, or any other activity where the bq27505 needs to determine
whether a battery is connected or not, the fuel gauge applies a test for battery presence. First, the
BI/TOUT pin is put into high-Z status. The weak 1.8MΩ pull-up resistor will keep the pin high while no
battery is present. When a battery is inserted (or is already inserted) into the system device, the BI/TOUT
pin will be pulled low. This state is detected by the fuel gauge, which polls this pin every second when the
gauge has power. A battery-disconnected status is assumed when the bq27505 reads a thermistor voltage
that is near 2.5V.
5.3.6 SOC_INT pin
The SOC_INT pin generates a pulse with different pulse width under various conditions. Some features
needs to be enabled by setting the Operation Config. In any given one second, only one SOC_INT pulse
could be generated. In other words, the 1ms SOC_INT pulse could indicated multiple events generating
the 1ms pusles.
Table 5-5. SOC_INT Pulse Condition and Width
Enable Condition
SOC_Delta
Point
SOC_Delta ≠ 0
SOC1 Set Always
SOC1 Clear Always
SysDown Set Always
SysDown
Clear
Always
State
Change
SOC_Delta ≠ 0
Battery
Removal
INT_BREM bit is set in
OpConfig AND BIE bit is
set
OCV
Command
After Initialization
OCV
Command
INT_FOCV bit is set in
OpConfig
Data Flash
Write
After Initialization AND
DFWrIndWaitTime ≠ 0
Pulse Width
1 ms
1 ms
1 ms
1 ms
1 ms
1 ms
Comment
During charge, when the SOC is greater than (>) the points, 100% - n
× SOC_Delta and 100%;
During discharge, when the SOC reaches (≤) the points 100% - n ×
SOC_Delta and 0%;
where n is an integer starting from 0 to the number generating SOC no
less than 0%
When RSOC reached the SOC1 Set or Clear threshold set in the Data
Flash and BL_INT bit in Operation Configuration B is set.
When the Battery Voltage reached the SysDown Set or Clear threshold
set in the Data Flash
When there is a state change including charging, discharging and
relaxation. This function is disabled when SOC_Delta is set to 0.
1ms
This function is disabled when BIE is cleared.
About 165ms. Same
as the OCV
command execution
time period
SOC_INT pulses for the OCV command after the initialization.
About 165ms. Same
as the OCV
command execution
time period
This command is to generate the SOC_INT pulse during the
initialization.
Programmmable time
pluse flash erase and
write time
SOC_INT is used to indicate the data flash update. The gauge will wait
DFWrIndWaitTime times 5µs after the SOC_INT signal to start the
data flash update. This function is disabled if DFWrIndWaitTime is set
to 0.
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FUNCTIONAL DESCRIPTION
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