BQ24616 Datasheet, PDF (15/34 Pages) Texas Instruments – JEITA Guideline Compatible Stand-Alone Synchronous Switch-Mode Li-Ion or Li-Polymer Battery Charger with System Power Selector and Low Iq

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Regulation Voltage
V_RECH
Regulation Current
bq24616
Precharge
Current
Regulation
Phase
SLUSA49A – APRIL 2010 – REVISED MAY 2010
DETAILED DESCRIPTION
Fastcharge Current
Regulation Phase
Fastcharge Voltage
Regulation Phase
Termination
Charge
Current
V_LOWV
I_PRECH & I _TERM
Charge
Voltage
Precharge
Time
Fastcharge Safety Time
Figure 15. Typical Charging Profile
Battery Voltage Regulation
The bq24616 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 2.1V in 0 – 45°C range, giving the following equation for the
regulation voltage:
VBA _T
= 2.1
V
´
é
êë¹⁺
R2
R1
ù
úû
,
(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 in 10 – 60°C range. Battery charge current is sensed by
resistor R_SR connected between SRP and SRN. The full-scale differential voltage between SRP and SRN is
100mV. Thus, for a 10mΩ sense resistor, the maximum charging current is 10A. The equation for charge current
is:
I_CHARGE
=
V_ISET1
20 ´ R_SR
(2)
V_ISET1, the input voltage range of ISET1, is between 0V and 2V. The SRP and SRN pins are used to sense
voltage across R_SR with default value of 10mΩ; however, resistors of other values can also be used. A larger
sense resistor will give a larger sense voltage and a higher regulation accuracy, but at the expense of higher
conduction loss.
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