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BQ24152 Datasheet, PDF (14/38 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger with Full USB Compliance and USB-OTG Support
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bq24152
SLUS847 – JUNE 2008 ...................................................................................................................................................................................................... www.ti.com
DETAILED FUNCTIONAL DESCRIPTION
For a current limited power source, such as a USB host or hub, the high efficiency converter is critical in fully
using the input power capacity and charging the battery. Due to the high efficiency in a wide range of the input
voltage and battery voltage, the switching mode charger is a good choice for high speed charging with less
power loss and better thermal management.
The bq24152 is a highly integrated synchronous switch-mode charger with reverse boost function for USB OTG
support, featuring integrated MOSFETs and small external components, targeted at extremely space-limited
portable applications powered by 1-cell Li-Ion or Li-polymer battery pack.
The bq24152 usually has three operation modes: charge mode, boost mode, and high impedance mode. In
charge mode, the bq24152 supports a precision Li-ion or Li-polymer charging system for single-cell applications.
In boost mode, bq24152 boosts the battery voltage to VBUS for powering attached OTG devices. In high
impedance mode, the bq24152 stops charging or boosting and operates in a mode with low current from VBUS
or battery, to effectively reduce the power consumption when the portable device in standby mode. Through the
proper control, bq24152 can achieve the smooth transition among different operation modes.
CHARGE MODE OPERATION
Charge Profile
In charge mode, bq24152 has four control loops to regulate input current, charge current, charge voltage and
device junction temperature, as shown in Figure 21. During the charging process, all four loops are enabled and
the one that is dominant will take over the control. The bq24152 supports a precision Li-ion or Li-polymer
charging system for single-cell applications. Figure 24(a) indicates a typical charge profile without input current
regulation loop and it is similar to the traditional CC/CV charge curve, while Figure 24(b) shows a typical charge
profile when input current limiting loop is dominant during the constant current mode, and in this case the charge
current is higher than the input current so the charge process is faster than the linear chargers. For bq24152, the
input current limits, the charge current, termination current, and charge voltage are all programmable using I2C
interface.
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