Single-input 2A standalone I2C switch-mode Li-ion battery charger

01-12-2015 | Texas Instruments | Power

This post is sponsored by Texas Instruments.

The bq24250, bq24251, and bq24253 from Texas Instruments (TI) are
highly-integrated single-cell Li-Ion battery chargers and system power-path
management devices aimed at space-limited, portable applications with
high-capacity batteries. The single-cell charger has a single input that
operates from either a USB port or an AC wall adapter for a versatile
solution.

The power-path management feature allows the bq24250, bq24251, and bq24253
to power the system from a high-efficiency DC-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. This reduced
charge current allows for proper charge termination and enables the system
to run with a defective or absent battery pack. Additionally, this reduced
charge current enables instant system turn-on even with a totally discharged
battery or no battery. The architecture of the power-path management also
permits the battery to supplement the system current requirements when the
adapter cannot deliver the peak system currents. This supplementation of
current requirements enables the use of a smaller adapter.

The battery is charged in four phases: trickle charge, pre=charge, constant
current, and constant voltage. In all charge phases, an internal control
loop monitors the IC junction temperature and reduces the charge current if
the internal temperature threshold is exceeded. Additionally, a
voltage-based, JEITA compatible battery pack thermistor monitoring input
(TS) that monitors battery temperature for safe charging is included, says
the company.

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