BQ24075-Q1_15 Datasheet, PDF (23/38 Pages) Texas Instruments – SLUSAU3B –FEBRUARY 2012–REVISED MARCH 2012

bq24075-Q1
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Input State
V_IN > V_OVP
SLUSAU3B – FEBRUARY 2012 – REVISED MARCH 2012
Table 2. PGOOD STATUS INDICATOR (continued)
PGOOD Output
Hi impedance
Charge State
Charging
Charging suspended by thermal loop
Safety timers expired
Charging done
Recharging after termination
IC disabled or no valid input power
Battery absent
Table 3. CHG STATUS INDICATOR
CHG Output
Low (for first charge cycle)
Flashing at 2Hz
Hi impedance
THERMAL REGULATION AND THERMAL SHUTDOWN
The bq24075-Q1 contain a thermal regulation loop that monitors the die temperature. If the temperature exceeds
T_J(REG), the device automatically reduces the charging current to prevent the die temperature from increasing
further. In some cases, the die temperature continues to rise despite the operation of the thermal loop,
particularly under high VIN and heavy OUT system load conditions. Under these conditions, if the die
temperature increases to T_J(OFF), the input FET Q1 is turned OFF. FET Q2 is turned ON to ensure that the
battery still powers the load on OUT. Once the device die temperature cools by T_J(OFF-HYS), the input FET Q1 is
turned on and the device returns to thermal regulation. Continuous overtemperature conditions result in a
"hiccup" mode. During thermal regulation, the safety timers are slowed down proportionately to the reduction in
current limit.
Note that this feature monitors the die temperature of the bq24075-Q1. This is not synonymous with ambient
temperature. Self heating exists due to the power dissipated in the IC because of the linear nature of the battery
charging algorithm and the LDO associated with OUT. A modified charge cycle with the thermal loop active is
shown in Figure 30. Battery termination is disabled during thermal regulation.
Copyright © 2012, Texas Instruments Incorporated
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