BQ24610_2 Datasheet, PDF (15/33 Pages) Texas Instruments – Stand-Alone Synchronous Switch-Mode Li-Ion or Li-Polymer Battery Charger with System Power Selector and Low Iq

www.ti.com
Regulation Voltage
V_RECH
Regulation Current
Precharge
Current
Regulation
Phase
DETAILED DESCRIPTION
Fastcharge Current
Regulation Phase
Fastcharge Voltage
Regulation Phase
Charge
Current
bq24610
bq24617
SLUS892 – DECEMBER 2009
Termination
V_LOWV
I_PRECH & I _TERM
Charge
Voltage
Precharge
Time
Fastcharge Safety Time
Figure 16. Typical Charging Profile
Battery Voltage Regulation
The bq24610/7 uses a high accuracy voltage bandgap and regulator for the high charging voltage accuaracy.
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, 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. 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, a higher regulation accuracy; but, at the expense of higher
conduction loss.
Copyright © 2009, Texas Instruments Incorporated
Product Folder Link(s): bq24610 bq24617
Submit Documentation Feedback
15