7
FN9212.1
January 3, 2006
Floating Charge Voltage
The floating voltage during the constant voltage phase is
4.2V. The floating voltage has an 1% accuracy over the
ambient temperature range of -40°C to 70°C.
Trickle Charge Current
When the battery voltage is below the minimum battery
voltage V
MIN
given in the electrical specification, the charger
operates in a trickle/preconditioning mode, where the charge
current is typically 14% of the programmed charge current
for the cradle input. If power comes from the USB input, the
trickle mode current is approximately 53mA.
End-of-Charge Indication
The CHG pin internal open-drain MOSFET turns off when
the charge current falls below the I
MIN
threshold, which is
programmable for the cradle input and fixed for the USB
input. Once the end-of charge-current is reached, the CHG
status will be latched. The latch can be reset at one of the
following conditions:
1. The part is disabled and re-enabled
2. The selected input source has been removed and re-
applied
3. The USBON turns LOW and turns back to HIGH for the
USB input
4. The BAT pin voltage falls below the recharge threshold
(~4.0V)
Regardless of the CHG pin status, however, the charger
does not turn off as long as an input power source is
attached.
Power Presence Indication
When either the USB or the cradle input voltage is above the
POR threshold, the PPR pin internal open-drain MOSFET
turns on indicating the presence of input power.
Power-Good Range
Even if there is a power present, the charger will not deliver
any current to the output if the power-good conditions are
not met. The following two conditions together define the
power-good voltage range:
1. VCDRL or VUSB > VPOR
2. VCDRL or VUSB - VBAT > VOS
where the VOS is the offset voltage for the input and output
voltage comparator, discussed shortly. Both VPOR, VOS
have hysteresis, as given in the Electrical Specification table.
The charger will not charge the battery if the input voltage
does not meet the power-good conditions.
Thermal Foldback (Thermaguard™)
The thermal foldback function reduces the charge current
when the internal temperature reaches the thermal foldback
threshold, which is typically 100°C. This protects the charger
from excessive thermal stress at high input voltages.
ISL6299A
