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| BQ24232HA Datasheet, PDF (17/36 Pages) Texas Instruments – USB-Friendly Lithium-Ion Battery Charger | |||
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www.ti.com
bq24232HA
SLUSCG4 â MAY 2016
Feature Description (continued)
7.3.4 Thermal Regulation and Thermal Shutdown
The bq24232HA contain a thermal regulation loop that monitors the die temperature. If the die temperature
exceeds TJ(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 TJ(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 TJ(OFF-HYS), the input FET Q1 is
turned on and the device returns to thermal regulation. Continuous overtemperature conditions result in a hiccup
mode. Safety timers are slowed proportionally to the charge current in thermal regulation. Battery termination is
disabled during thermal regulation and thermal shutdown.
Note that this feature monitors the die temperature of the bq24232HA. 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 mode for OUT.
A modified charge cycle with the thermal loop active is shown in Figure 12:
PRECHARGE
THERMAL
REGULATION
CC FAST
CHARGE
CV TAPER
DONE
VO(REG)
IO(CHG)
Battery Voltage
Battery Current
V(LOWV)
I(PRECHG)
I(TERM)
HI-z
TJ(REG)
IC Junction Temperature, TJ
Figure 12. Modified Charge Cycle
Copyright © 2016, Texas Instruments Incorporated
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