Datasheet

VTSB
TS
RT1
RTH
103 AT
bq24210
bq24210
www.ti.com SLUSA76A –DECEMBER 2010– REVISED MAY 2011
Figure 13. TS Resistor Network
The TS pin has another additional feature. When the TS pin is driven high (V
TS
> V
LP(TS)
), the IC operates in
Limited Power Charge mode.
Limited Power Charge Mode – TS Pin High
When the TS pin goes high to the Limited Power Charge Mode (LPCM) threshold (V
LP(TS)
), the part enters
Limited Power Charge mode. This mode is used normally for solar charging applications or other high impedance
input sources that desire to modify the termination routine and other timers. When entering the Limited Power
Charging mode, the pre-charge timer and 10 hour safety timer is held in reset, and the termination routine is
modified. A battery detect routine is run to see if the battery was removed or not. If the battery was removed then
the CHG pin will go to its high impedance state if not already there. If a battery is detected, the normal charge
process begins. If the normal termination conditions are met (Icharge<I
TERM
, BAT>V
RCH
) and VBUS_DPM loop is
not active, the charging process terminates, and the CHG pin goes to its high impedance state if not already
there. When the regular timers are disabled there still is a 2 hour timer if the part is stuck in DPM above 4.1 V but
outside of termination conditions at which point charging will terminate and re-start if the voltage falls below 4.1V.
When coming out of the Limited Power Charging mode, the battery detect routine is run and if a battery is
detected, then a new charge cycle begins and the CHG LED turns on.
Limited Power Charge mode is not necessary for all solar charging. A solar panel charging in normal mode
without TS pulled high would keep the normal termination timers active and would allow the TS temperature
monitoring functions to be used.
If Limited Power Charging mode is not desired upon removal of the battery with a thermister, apply a voltage
equal to 30% VTSB on TS pin using two external resistors to set a voltage divider and disable the TS monitor
function.
Timers
The pre-charge timer is set to 30 minutes. The pre-charge current is internally set to 20% of the fast charge
current.
The fast charge timer is fixed at 10 hours and can be increased real time by going into thermal regulation or
VBUS_DPM. While in thermal regulation or VBUS_DPM, the timer clock slows by a factor of 2, resulting in a
clock than counts half as fast which will increase the total time. If either the 30 minute or ten hour timer times out,
the charging is terminated and the CHG pin goes high impedance if not already in that state. The timer is reset
by disabling the IC, cycling power, or going into and out of LPCM.
Termination
Once the BAT pin goes above VRCH (reaches voltage regulation), and the current tapers down to the
termination threshold, the CHG pin goes high impedance, and a battery detect route is run to determine if the
battery was removed or the battery is full. If the battery is present, the charge current will terminate. If the battery
was removed along with the thermister, then the TS pin is driven high and the charger enters LPCM. If the
battery was removed and the TS pin is held in the active region, then the battery detect routine will continue until
a battery is inserted.
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