Charging Circuit - LG GX500 Service Manual

GX500 Operational Description

3.12 Charging circuit

The bq25040 has a single power output that charges the battery. A system load can be placed in parallel with
the battery. The charge current is programmed using the ISET and EN/SET inputs. The input current limit is
programmable to USB100, USB500 or a user programmed current limit up to 1.1A. Additionally, a 4.9V ±3%
50mA LDO is integrated into the IC for supplying low power external circuitry. The single-input interface
(EN/SET) is used to select the charge current and to place the bq25040 into Production Test Mode. In
Production Test Mode, the bq25040 operates as a linear regulator without a battery connected, where the
output is regulated at 4.2V and supplies up to 2.3A to calibrate GSM transceivers.
RPWRON_EN
Figure 3-23 Charging circuit
Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LG Electronics
SINGLE CHARGING IC
V_BUS
1
IN
2
ISET
BQ25040
3
VSS1
4
LDO
5
IFULL
C338 C337
1uF 1uF
560 ohm->(910mA) 2K(10%)->91mA
780 ohm->(680mA)
820 ohm->(646mA)
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3. TECHNICAL BRIEF
VBAT 2V62_VIO 2V62_VIO
11
PGND
10
BAT
9
U310
_PG
8
CHG
7
VSS2
6
EN_SET
C336
1uF
Revision A
2V62_VIO
_PPR
_EOC
_CHG_EN
LGE Internal Use Only
LGE Property