Datasheet

ISET1
CHARGE
SR
V
I =
20 R´
R2
V = 2.1 V 1+ ,
BAT
R1
é ù
´
ê ú
ë û
V
LOWV
V
RECH
I
PRECH
& I
TERM
Precharge
Time
FastchargeSafetyTime
Precharge
Current
Regulation
Phase
FastchargeCurrent
RegulationPhase
FastchargeVoltage
RegulationPhase
Termination
Charge
Voltage
Charge
Current
RegulationCurrent
RegulationVoltage
bq24610
bq24617
www.ti.com SLUS892B –DECEMBER 2009–REVISED SEPTEMBER 2013
DETAILED DESCRIPTION
Figure 16. Typical Charging Profile
Battery Voltage Regulation
The bq24610/7 uses a high-accuracy voltage bandgap and regulator for the high charging-voltage accuracy. The
charge voltage is programmed via a resistor divider from the battery to ground, with the midpoint tied to the VFB
pin. The voltage at the VFB pin is regulated to 2.1 V, giving the following equation for the regulation voltage:
(1)
where R2 is connected from VFB to the battery and R1 is connected from VFB to GND.
Battery Current Regulation
The ISET1 input sets the maximum fast-charging current. Battery charge current is sensed by resistor R
SR
connected between SRP and SRN. The full-scale differential voltage between SRP and SRN is 100 mV. Thus,
for a 10-mΩ sense resistor, the maximum charging current is 10 A. The equation for charge current is:
(2)
V
ISET1
, the input voltage range of ISET1, is between 0 V and 2 V. The SRP and SRN pins are used to sense
voltage across R
SR
with default value of 10 mΩ. However, resistors of other values can also be used. A larger
sense resistor gives a larger sense voltage and a higher regulation accuracy, but at the expense of higher
conduction loss.
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