Datasheet

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
R2
V = 2.1 V 1+
BAT
R1
é ù
´
ê ú
ë û
ISET
CHARGE
SR
V
I =
20 R´
bq24600
www.ti.com SLUS891A –FEBRUARY 2010– REVISED OCTOBER 2011
DETAILED DESCRIPTION
Figure 13. Typical Charging Profile
Battery Voltage Regulation
The bq24600 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 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 ISET input sets the maximum charging current. Battery 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
ISET
, The input voltage range of ISET is between 0 and 2 V. The SRP and SRN pins are used to sense voltage
across RSR 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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Product Folder Link(s): bq24600