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| BQ24230 Datasheet, PDF (18/33 Pages) Texas Instruments – USB-FRIENDLY LITHIUM-ION BATTERY CHARGER AND POWER-PATH MANAGEMENT IC | |||
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bq24230
bq24232
SLUS821A â OCTOBER 2008 â REVISED DECEMBER 2008 .......................................................................................................................................... www.ti.com
Figure 28 illustrates a normal Li-ion charge cycle using the bq2423x:
PRECHARGE
CC FAST CHARGE
CV TAPER
DONE
VBAT(REG)
IO(CHG)
Battery Current
VLOWV
I(PRECHG)
I(TERM)
Battery Voltage
CHG = Hi-z
Figure 28.
In the precharge phase, the battery is charged with the precharge 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(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
ICHG = KISET/RISET
The charge current limit is adjustable from 25 mA to 500 mA. The valid resistor range is 1.8 k⦠to 36 kâ¦. Note
that if ICHG is programmed as greater than the input current limit, the battery does 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
are proportionately slowed down.
18
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Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): bq24230 bq24232
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