BQ24153A Datasheet, PDF (16/43 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger

bq24153A
bq24156A, bq24158
SLUSAB0 – OCTOBER 2010
www.ti.com
DETAILED FUNCTIONAL DESCRIPTION
For a current restricted power source, such as a USB host or hub, a high efficiency converter is critical to fully
use the input power capacity for quickly charging the battery. Due to the high efficiency for a wide range of input
voltages and battery voltages, the switch mode charger is a good choice for high speed charging with less power
loss and better thermal management than a linear charger.
The bq24153A/6A/8 are highly integrated synchronous switch-mode chargers, featuring integrated FETs and
small external components, targeted at extremely space-limited portable applications powered by 1-cell Li-Ion or
Li-polymer battery pack. Furthermore, bq24153A/8 also has bi-directional operation to achieve boost function for
USB OTG support.
The bq24153A/8 have three operation modes: charge mode, boost mode, and high impedance mode, while
bq24156A only has charge mode and high impedance mode. In charge mode, the IC supports a precision Li-ion
or Li-polymer charging system for single-cell applications. In boost mode, the IC boosts the battery voltage to
VBUS for powering attached OTG devices. In high impedance mode, the IC stops charging or boosting and
operates in a mode with very low current from VBUS or battery, to effectively reduce the power consumption
when the portable device is in standby mode. Through the proper control, the IC achieves the smooth transition
among the different operation modes.
CHARGE MODE OPERATION
Charge Profile
In charge mode, the IC has five control loops to regulate input voltage, input current, charge current, charge
voltage and device junction temperature. During the charging process, all five loops are enabled and the one that
is dominant takes control. The IC supports a precision Li-ion or Li-polymer charging system for single-cell
applications. Figure 26 (a) indicates a typical charge profile without input current regulation loop. It is the
traditional CC/CV charge curve, while Figure 26(b) shows a typical charge profile when input current limiting loop
is dominant during the constant current mode. In this case, the charge current is higher than the input current so
the charge process is faster than the linear chargers. For bq24153A/6A/8, the input voltage threshold for DPM
loop, input current limits, the charge current, termination current, and charge voltage are all programmable using
I²C interface.
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