Usb Charging Circuit; Only For Training And Service Purposes - LG KC780 Service Manual

3.14. 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
I resistor between this pin and the GND pin to set the charge current limit determined by the following
REF
equation:
I = 6820/33K = 207mA
CC
The End Of Charging current is set by I
I = 550/5.1K = 107mA
EOC
Add for Charging Trouble
Copyright © 2008 LG Electronics. Inc. All right reserved.

Only for training and service purposes

& I resistors.
REF MIN
That can be programmed by the as following equation:
MIN
VIO_2V62
VBUS_USB
R417
R416
100K
100K
CHG_PPR
CHG_EOC
CHG_EN
C413
1u
Figure 26 USB charging circuit
CHARGING IC
VCHG
U401
1
VDC
VDC_BYP
2
VUSB
3
_PPR
USB_BYP
4
_CHG
5
_EN
6
IMIN
R420
C414
5.1K
1u
- 53 -
3. TECHNICAL BRIEF
VBAT
ISL9221
13
PGND
12
OVP_VCHG
11
BAT
10
OVP_VUSB
9
IVDC
8
GND
7
IUSB
R421 R419
33K 15K
LGE Internal Use Only
C415
1u