Datasheet

V
BAT(REG)
I
O(CHG)
V
LOWV
I
(TERM)
PRECHARGE
CCFASTCHARGE CVTAPER
DONE
Battery
Voltage
BatteryCurrent
TERMCURRENT=1
I
(PRECHG)
TPS65070, TPS65072, TPS65073
TPS650731, TPS650732, TPS650701, TPS650702, TPS650721
SLVS950G JULY 2009REVISED MAY 2013
www.ti.com
Figure 27. Battery Charge
In the pre-charge phase, the battery is charged at a current of I
PRECHG
. The battery voltage starts rising. Once the
battery voltage crosses the V
LOWV
threshold, the battery is charged at a current of I
CHG
. The battery voltage
continues to rise. When the battery voltage reaches V
BAT(REG)
, the battery is held at a constant value of V
BAT(REG)
.
The battery current now decreases as the battery approaches full charge. When the battery current reaches
I
TERM
, the TERM CURRENT flag in register CHGCONFIG0 indicates charging done by going high.
Note that termination detection is disabled whenever the charge rate is reduced from the set point because of the
actions of the thermal loop, the DPM loop or the V
IN-LOW
loop.
The value of the fast-charge current is set by the resistor connected from the ISET pin to GND, and is given by
the equation
I
CHG
= K
ISET
/ R
ISET
(1) (1)
R
ISET
= K
ISET
/ I
CHG
(2) (2)
Note that if I
CHG
is programmed as greater than the input current limit, the battery will not charge at the rate of
I
CHG
, but at the slower rate of I
IN-MAX
(minus the load current on the OUT pin, if any). In this case, the charger
timers will be slowed down by 2x whenever the thermal loop or DPPM is active.
I-PRECHARGE:
The value for the pre-charge current is fixed to a factor of 0.1 of the fast charge current (full scale current)
programmed by the external resistor Rset
ITERM:
The value for the termination current threshold can be set in register CHGCONFIG3 using Bits TERMINATION
CURRENT FACTOR 0 and TERMINATION CURRENT FACTOR 1. The termination current is pre-set to a factor
of 0.1 of the fast charge current programmed by the external resistor Rset.
Battery Detection and Recharge:
Whenever the battery voltage falls below V
RCH
(Vset-100mV), a check is performed to see whether the battery
has been removed: current I
BAT(DET)
is pulled from the battery for a duration t
DET
. If the voltage on the BAT pin
remains above V
LOWV
, it indicates that the battery is still connected. If the charger is enabled by Bit CHARGER
ENABLE in register CHGCONFIG1 set to 1, the charger is turned on again to top up the battery.
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