BQ24100_08 Datasheet, PDF (14/38 Pages) Texas Instruments – SYNCHRONOUS SWITCHMODE, LI-ION AND LI-POLYMER CHARGE-MANAGEMENT IC WITH INTEGRATED POWER FETs (bqSWITCHER™)

bq24100, bq24103, bq24103A
bq24104, bq24105, bq24108, bq24109
bq24113, bq24113A, bq24115
SLUS606N – JUNE 2004 – REVISED NOVEMBER 2008 .................................................................................................................................................. www.ti.com
Temperature Qualification
The bqSWITCHER continuously monitors battery temperature by measuring the voltage between the TS pin and
VSS pin. A negative temperature coefficient thermistor (NTC) and an external voltage divider typically develop
this voltage. The bqSWITCHER compares this voltage against its internal thresholds to determine if charging is
allowed. To initiate a charge cycle, the battery temperature must be within the V_(LTF)-to-V_(HTF) thresholds. If
battery temperature is outside of this range, the bqSWITCHER suspends charge and waits until the battery
temperature is within the V_(LTF)-to-V_(HTF) range. During the charge cycle (both precharge and fast charge), the
battery temperature must be within the V_(LTF)-to-V_(TCO) thresholds. If battery temperature is outside of this range,
the bqSWITCHER suspends charge and waits until the battery temperature is within the V_(LTF)-to-V_(HTF) range.
The bqSWITCHER suspends charge by turning off the PWM and holding the timer value (i.e., timers are not
reset during a suspend condition). Note that the bias for the external resistor divider is provided from the VTSB
output. Applying a constant voltage between the V_(LTF)-to-V_(HTF) thresholds to the TS pin disables the
temperature-sensing feature.
RT2 =
V_O(VTSB) ´ RTH_COLD ´ RTH_HOT ´
1
1
V_LTF ^- V_HTF
( ) ( ) ^{RTHHOT ´}
V_O(VTSB)
V_HTF
-1
- RTH_COLD ´
V_O(VTSB)
V_LTF
-1
RT1 =
V_O(VTSB)
V_LTF
-1
Where:
V_LTF = V_O(VTSB) ´ % _LTF¸100 / 100
1
1
+
V_HTF = V_O(VTSB) ´ % _HTF¸100 / 100
RT2 RTH_COLD
(1)
V_CC
Charge Suspend
Charge Suspend
V_(LTF)
V_(HTF)
V_(TCO)
V_SS
Temperature Range
to Initiate Charge
Charge Suspend
Temperature Range
During Charge Cycle
Charge Suspend
Figure 10. TS Pin Thresholds
Battery Preconditioning (Precharge)
On power up, if the battery voltage is below the V_LOWV threshold, the bqSWITCHER applies a precharge current,
I_PRECHG, to the battery. This feature revives deeply discharged cells. The bqSWITCHER activates a safety timer,
t_PRECHG, during the conditioning phase. If the V_LOWV threshold is not reached within the timer period, the
bqSWITCHER turns off the charger and enunciates FAULT on the STATx pins. In the case of a FAULT
condition, the bqSWITCHER reduces the current to I_DETECT. I_DETECT is used to detect a battery replacement
condition. Fault condition is cleared by POR or battery replacement.
14
Submit Documentation Feedback
Copyright © 2004–2008, Texas Instruments Incorporated
Product Folder Link(s): bq24100 bq24103 bq24103A bq24104 bq24105 bq24108 bq24109 bq24113 bq24113A
bq24115