GX500 Operational Description Revision A
LG Electronics 59/143 LGE Property
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.
Figure 3-23 Charging circuit
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