Usb Charging Circuit - LG KE970 Service Manual

3. TECHNICAL BRIEF

3.15. USB charging circuit

The USB charging circuit is a fully integrated USB VBUS voltage single-cell Li-ion battery charger
circuit.
The charger uses a CC/CV charge profile required by Li-ion batteries. CC charging current and End of
charging current is programmable I
set the charge current limit determined by the following equation:
I = 12089/33K = 366mA
CC
The End Of Charging current is set by I
I = 11000/220K = 50mA
EOC
_USB_EOC
_USB_CHG_EN
Charging indicator LED controlled by two ICs, one is a SM-Power, the other is a ISL6294. When
TA(Travel Charger) is plugged in to MMI connector, the LD100 controlled by SM-Power both power off
case and power on case. When USB cable is connected via MMI connector, indicator LED is
controlled by ISL6294 in power off case and by SM-Power in power on case.
& I resistors. I
REF MIN
That can be programmed by the as following equation:
MIN
2V72_IO
VBUS_USB
R201
10K
C213
1u
Figure 25 USB charging circuit
- 50 -
resistor between this pin and the GND pin to
REF
U202 ISL6294
1 8
VIN BAT
2 7 360mA
_PPR IREF
3 6 50mA
_CHG IMIN
4 5
_EN GND
9
PGND
R208 R209
220K 33K
VBAT
C214
1u