Data Sheet

A
1200mA
900mA
400mA
0mA
I
OUT
900mA
500mA
0mA
I
IN
500mA
-300mA
0mA
I
BAT
4.4V
4.3V
~3.6V
V
OUT
DPPMLoop Active
SupplementMode
bq24072 , bq24073 , bq24074 , bq24075 , bq24079
SLUS810K –SEPTEMBER 2008–REVISED MARCH 2015 www.ti.com
Feature Description (continued)
Figure 20. bq24073 DPPM and Battery Supplement Modes (V
OREG
= 4.4 V, V
BAT
= 3.6 V)
9.3.4.2 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 250 mV for longer than t
DGL(SC2)
, OUT is turned off. The
short circuit recovery timer then starts counting. After t
REC(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.
9.3.5 Battery Charging
Set CE low to initiate battery charging. First, the device checks for a short-circuit on the BAT pin by sourcing
I
BAT(SC)
to the battery and monitoring the voltage. When the BAT voltage exceeds V
BAT(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 21 illustrates a normal Li-Ion charge cycle using the bq2407x:
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