Datasheet

PRECHARGE CCFASTCHARGE CVTAPER DONE
BatteryVoltage
BatteryCurrent
CHG=Hi-z
V
BAT(REG)
I
O(CHG)
V
LOWV
I
(PRECHG)
I
(TERM)
bq24230
bq24232
www.ti.com SLUS821E –OCTOBER 2008–REVISED JANUARY 2014
Figure 28.
In the precharge phase, the battery is charged with the precharge current (I
PRECHG
). Once the battery voltage
crosses the V
LOWV
threshold, the battery is charged with the fast-charge current (I
CHG
). As the battery voltage
reaches V
BAT(REG)
, the battery is held at a constant voltage of V
BAT(REG)
and the charge current tapers off as the
battery approaches full charge. When the battery current reaches I
TERM
, 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 V
IN(LOW)
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
I
CHG
= K
ISET
/R
ISET
The charge current limit is adjustable from 25 mA to 500 mA. The valid resistor range is 1.8 kΩ to 36 kΩ. Note
that if I
CHG
is programmed as greater than the input current limit, the battery does not charge at the rate of I
CHG
,
but at the slower rate of I
IN(MAX)
(minus the load current on the OUT pin, if any). In this case, the charger timers
are proportionately slowed down.
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