BQ24188_15 Datasheet, PDF (12/52 Pages) Texas Instruments – bq24188 2A, 30V, Host-Controlled Single-Input, Single Cell Switchmode Li-Ion Battery Charger with Power Path Management and USB-OTG Support

bq24188
SLUSC44A – DECEMBER 2014 – REVISED MAY 2015
9 Detailed Description
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9.1 Overview
The bq24188 is a highly integrated single cell Li-Ion battery charger and system power path management device
targeted for space-limited, portable applications with high capacity batteries. The single cell charger has a single
input that supports operation from either a USB port or wall adapter supply for a versatile solution.
The power path management feature allows the bq24188 to power the system from a high efficiency DC to DC
converter while simultaneously and independently charging the battery. The charger monitors the battery current
at all times and reduces the charge current when the system load requires current above the input current limit or
the adapter cannot support the required load, causing the adapter voltage to fall (V_{IN_DPM}). This allows for proper
charge termination and timer operation. The system voltage is regulated to the battery voltage but will not drop
below 3.5V (V_MINSYS). This minimum system voltage support enables the system to run with a defective or absent
battery pack and enables instant system turn-on even with a totally discharged battery or no battery. The power-
path management architecture also permits the battery to supplement the system current requirements when the
adapter cannot deliver the peak system currents. The power-path feature coupled with V_IN-DPM, enables the use
of many adapters with no hardware change. The charge parameters are programmable using the I2C interface.
To Support USB OTG applications, the bq24188 is configurable to boost the battery voltage to 5V at the input. In
this mode, the bq24188 supplies up to 1A and operates with battery voltages down to 3.3V.
The battery is charged using a standard Li-Ion charge profile with three phases: precharge, constant current and
constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces
the input current to prevent the junction temperature from rising above 125°C. Additionally, a voltage-based,
JEITA compatible battery pack thermistor monitoring input (TS) is included that monitors battery temperature and
automatically changes charge parameters to prevent the battery from charging outside of its safe temperature
range.
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