ICS1712
Battery Polling
Upon power-up or after a reset is issued, any excess charge from
filter capacitors at the charging system terminals is removed with a
series of discharge pulses. After the discharge pulse series is
complete, the voltage at VIN must be greater than 0.5V when a
battery is present. If the voltage at VIN is less than 0.5V, the
ICS1712
assumes no battery is attached and initiates a polling
sequence.
The
ICS1712
then applies a 100ms charge pulse. During the pulse,
the
ICS1712
monitors the VIN pin to determine if the divided
down terminal voltage is greater than the internal 2.0V reference. If
the battery is present, the voltage is clamped below the 2.0V
reference when the current pulse is applied and the fast charge
stage begins immediately. If a battery is not present, the voltage at
VIN rises above the 2.0V reference and the PFN fault indicator is
activated.
The charge pulses repeat for 10 seconds. If the battery is installed
within 10 seconds, the
ICS1712
will turn off the PFN fault
indicator and enter the soft start stage. If the battery is not installed
within 10 seconds, the PFN fault indicator remains active and the
ICS1712
shuts down. A reset must be issued to restart the
controller after installing the battery.
Battery Fault Detection
The
ICS1712
will turn on the PFN fault indicator and shut down if
the battery is removed or if an open circuit occurs in the current
path anytime after fast charge has been initiated.
When in the topping charge or maintenance charge stages, a charge
pulse may not occur for several seconds. During the period
between charge pulses, the voltage at VIN should be greater than
0.5V if a battery is attached. If the voltage at VIN is less than 0.5V,
the
ICS1712
assumes the battery has been removed, a fault
condition is indicated by the PFN fault indicator, and the controller
shuts down.
Cold Battery Charging
Cold battery charging is activated if a voltage at the THERM pin is
in the cold battery voltage range, as shown in Figure 7.
The
ICS1712
checks for a cold battery before initiating fast charge.
If a cold battery is present before fast charging begins, the
ICS1712
begins a two hour C/10 topping charge (the pulsed duty
cycle is based on the selected charge rate). If the battery is still cold
after the two hour topping charge is complete, the
ICS1712
begins
a C/40 maintenance charge. The maintenance charge will continue
for as long as the battery remains cold. The thermistor voltage at
the THERM pin is checked every second to see if the battery has
warmed up. If so, the
ICS1712
stops the topping charge or
maintenance charge and begins a fast charge at a rate selected by
the SEL0 and SEL1 inputs. See the section on
Temperature
Sensing
for more information.
The CMN will flash at a one second rate, and the OTN indicator
will be active, indicating that a low current charge is being applied
to a battery that is outside the specified temperature range for fast
charging.
9
GALAXY [ GALAXY POWER, INC. ]
