LG KE 770, Service Manual

Page: 35 / 144

3.3.2. Charging
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 100°C, 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.
3. TECHNICAL BRIEF
- 36 -
CHARGIING IC
100K
R315 C313
VCHG
1u
R318
100K
VBUS_USB
1u
C311
USB
2
7
USBON
_CHG
4
5
_EN
3
_PPR
R319
10K
U301
ISL6299
10
BAT
1
CRDL
GND
8
9
ICDL
IMIN
6
11
PGND
1u
C312
R312
10K
USFB13L
D301 2V72_IO
100K
R311
VBAT
R314
39K
CHG_EN
EOC
Figure 7 Charging IC Circutit
Figure 6 Battery Block Indication
3.69V~3.57V 4.2V~3.86V 3.85V~3.75V 3.74V~3.70V