BQ24072T_2 Datasheet, PDF(20/36 Page) Texas Instruments – 1.5A USB-Friendly Li-Ion Battery Charger and Power-Path Management IC

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

BQ24072T_2 Datasheet, PDF (20/36 Pages) Texas Instruments – 1.5A USB-Friendly Li-Ion Battery Charger and Power-Path Management IC

◁

bq24072T

bq24075T, bq24079T

SLUS937A â DECEMBER 2009 â REVISED APRIL 2010

www.ti.com

INPUT SOURCE NOT CONNECTED

When no source is connected to the IN input, OUT is powered strictly from the battery. During this mode the

current into OUT is not regulated, similar to Battery Supplement Mode, however the short circuit circuitry is

active. If the OUT voltage falls below the BAT voltage by 250mV for longer than tDGL(SC2), OUT is turned off. The

short circuit recovery timer then starts counting. After tREC(SC2), OUT turns on and attempts to restart. If the short

circuit remains, OUT is turned off and the counter restarts. This ON/OFF cycle continues until the overload

condition is removed.

BATTERY CHARGING

Set CE low to initiate battery charging. First, the device checks for a short-circuit on the BAT pin by sourcing

IBAT(SC) to the battery and monitoring the voltage. When the BAT voltage exceeds VBAT(SC), the battery charging

continues. The battery is charged in three phases: conditioning pre-charge, constant current fast charge (current

regulation) and a constant voltage tapering (voltage regulation). In all charge phases, an internal control loop

monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is

exceeded.

Figure 32. Typical Charging Cycle

Figure 32 illustrates a normal Li-Ion charge cycle using the bq2407xT. In the pre-charge phase, the battery is

charged at with the pre-charge current (IPRECHG). Once the battery voltage crosses the VLOWV threshold, the

battery is charged with the fast-charge current (ICHG). As the battery voltage reaches VBAT(REG), the battery is held

at a constant voltage of VBAT(REG) and the charge current tapers off as the battery approaches full charge. When

the battery current reaches ITERM, the CHG pin indicates charging done by going high-impedance.

Note that termination detection is disabled whenever the charge rate is reduced because of the actions of the

thermal loop, the DPPM loop or the VIN-DPM loop.

The value of the fast-charge current is set by the resistor connected from the ISET pin to VSS, and is given by

the equation

ICHG = KISET / RISET

The charge current limit is adjustable up to 1.5A. The valid resistor range is 590â¦ to 3 kâ¦. Note that if ICHG is

programmed as greater than the input current limit, the battery will not charge at the rate of ICHG, but at the

slower rate of IIN(MAX) (minus the load current on the OUT pin, if any). In this case, the charger timers will be

proportionately slowed down.

Submit Documentation Feedback

Product Folder Link(s): bq24072T bq24075T bq24079T

▷