Texas Instruments System-Side Impedance Track(TM) Fuel Gauge bq27500 Manual De Usuario
www.ti.com
5.3.5
Battery Detection Using the BI/TOUT Pin
bq27500
bq27501
System-Side Impedance Track™ Fuel Gauge
bq27501
System-Side Impedance Track™ Fuel Gauge
SLUS785 – SEPTEMBER 2007
for the fuel gauge to take an accurate OCV reading. To disable these functions, the BAT_GD pin is merely
set high (floating output pulled high). Once an OCV reading has be made, the BAT_GD pin is pulled low,
thereby enabling battery charging and regular discharge of the battery. The Operation Configuration
[BATG_POL] bit can be used to set the polarity of the battery good signal, should the default configuration
need to be changed.
set high (floating output pulled high). Once an OCV reading has be made, the BAT_GD pin is pulled low,
thereby enabling battery charging and regular discharge of the battery. The Operation Configuration
[BATG_POL] bit can be used to set the polarity of the battery good signal, should the default configuration
need to be changed.
The flowchart of
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 bq27500/1 reads battery
temperatures outside the range defined by [Charge Inhibit Temp Low, Charge Inhibit Temp High]. The
BAT_GD line is returned to low once temperature falls within the range [Charge Inhibit Temp Low +
Temp Hys, Charge Inhibit Temp High – Temp Hys].
temperatures outside the range defined by [Charge Inhibit Temp Low, Charge Inhibit Temp High]. The
BAT_GD line is returned to low once temperature falls within the range [Charge Inhibit Temp Low +
Temp Hys, Charge Inhibit Temp High – Temp Hys].
During power-up or HIBERNATE activities, or any other activity where the bq27500/1 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 1.8M
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 1.8M
Ω
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 bq27500/1 reads a thermistor
voltage that is near 2.5V.
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 bq27500/1 reads a thermistor
voltage that is near 2.5V.
FUNCTIONAL DESCRIPTION
24