Datasheet

bq24272

www.ti.com

SLUSB09 –JUNE 2012

DETAILED DESCRIPTION

The bq24272 is a highly integrated single cell Li-Ion battery charger and system power path management

devices targeted for space-limited, portable applications with high capacity batteries. The single-input, single cell

charger operates from a dedicated power source (i.e. wall adapter or wireless power input).

The power path management feature allows the bq24272 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.

This allows for proper charge termination and enables the system to run with a defective or absent battery pack.

Additionally, this 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. This enables the use of a smaller adapter. The charge

parameters are programmable using the I2C interface.

The battery is charged in three phases: conditioning, 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.

Charge Mode Operation

Charge Profile

The internal battery MOSFET is used to charge the battery. When the battery is above the MINSYS voltage, the

internal FET is on to maximize efficiency and the PWM converter regulates the charge current into the battery.

When battery is less than MINSYS, the SYS is regulated to V

SYS(REG)

and battery is charged using the battery

FET to regulate the charge current. There are 5 loops that influence the charge current:

• Constant current loop (CC)

• Constant voltage loop (CV)

• Thermal-regulation loop

• Minimum system-voltage loop (MINSYS)

• Input-voltage dynamic power-management loop (VIN-DPM)

During the charging process, all five loops are enabled and the one that is dominant takes control. The bq24272

supports a precision Li-Ion or Li-Polymer charging system for single-cell applications. The Dynamic Power Path

Management (DPPM) feature regulates the system voltage to a minimum of VMINSYS, so that startup is enabled

even for a missing or deeply discharged battery. Figure 2 shows a typical charge profile including the minimum

system output voltage feature.

Product Folder Link(s) :bq24272