Datasheet

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
V
RECH
V
LOWV
I &I
PRECH TERM
BAT
R2
V = 1.8 V 1
R1
é ù
´ +
ê ú
ë û
ISET1
CHARGE
SR
V
I =
20 R´
bq24630
www.ti.com SLUS894A –JANUARY 2010– REVISED OCTOBER 2011
DETAILED DESCRIPTION
Figure 17. Typical Charging Profile
BATTERY VOLTAGE REGULATION
The bq24630 uses a high-accuracy voltage band gap and regulator for the high-accuracy charging voltage. 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 1.8 V, giving Equation 1 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-charge 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. Equation 2 is for charge current
(2)
V
ISET1
, the input voltage range of ISET1, is between 0 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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