LG KG290 Service Manual page 53

3. TECHNICAL BRIEF
8. TA /USB Charging (ISL6299)
The ISL6299 is a fully integrated low-cost single-cell Li-ion or Li-polymer battery charger. The charger
accepts two power inputs, normally one from a USB (Universal Serial Bus) port and the other from a
desktop cradle. The ISL6299 is an ideal charger for smart handheld devices that need to communicate
with a personal computer via USB.
The ISL6299 features 28V and 7V maximum voltages for the cradle and the USB inputs respectively.
Due to the 28V rating for the cradle input, low-cost, large output tolerance adapters can be used
safely. When both inputs are powered, the cradle input is used to charge the battery. The charge
current is programmable for the cradle input with a small resistor. The end-of-charge current for the
cradle input is also programmable by another external resistor. The charger incorporates
Thermaguard TM which protects the IC against over temperature. If the die temperature rises above a
typical value of 100C, a thermal foldback function reduces the charge current
automatically to prevent further temperature rise. The charger preconditions the battery with low
current when the battery voltage is below 2.6V. The charger has two indication pins. The PPR (power
present) pin outputs an open-drain logic LOW when either the cradle or the USB input power is
attached. The CHG (charge) pin is also an open-drain output that indicates a logic LOW when the
charge current is above a minimum current level. When the charge current is below the minimum
current, the CHG pin indicates a logic HIGH signal and the status is latched. The latch will be reset at
one of these events: (1) the part is disabled and re-enabled; (2) the selected input source has been
removed and re-applied, (3) The USBON turns LOW, or (4) The BAT pin voltage falls below the CV
mode threshold.
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