BQ25060_1 Datasheet, PDF (16/24 Pages) Texas Instruments – 1A, Single-Input, Single Cell Li-Ion Battery Charger with 50-mA LDO, and External Power Path Control

bq25060
SLUSA32 – MAY 2010
V CO L D
+
V H OT
+
LDO
TS
R1
TEM P
PAC K+
R2
PACK -
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bq25060
Figure 21. NTC Monitoring Function
50mA LDO (LDO)
The LDO output of the bq25060 is a low dropout linear regulator (LDO) that supplies up to 50mA while regulating
to VLDO. The LDO is active whenever the input voltage is above VUVLO and below VOVP. It is not affected by
the EN input. The LDO output is used to power circuitry such as USB transceivers in dead battery conditions.
This allows the user to operate the product immediately after plugging the adapter in, instead of waiting for the
battery to charge to useable levels.
Charge Status Indicator (CHG)
The bq25060 contains an open drain CHG output that indicates charge cycles and faults. When charging a
battery in precharge, fastcharge, or CV mode, the CHG output is pulled to VSS. Once the BAT output reaches
regulation and the charge current falls below the termination threshold, CHG goes to high impedance to signal
the battery is fully charged. The CHG output goes low during battery recharge cycles to signal the host to monitor
for termination.
Additionally, CHG notifies the host if a NTC temperature fault has occurred. CHG goes to high impedance if a TS
fault occurs. Connect CHG to the required logic level voltage through a 1kΩ to 100kΩ resistor to use the signal
with a microprocessor. I_CHG must be below 5mA.
Thermal Regulation and Thermal Shutdown
The bq25060 contains a thermal regulation loop that monitors the die temperature continuously. 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 V_IN conditions. If the die temperature increases to T_J(OFF), the IC is
turned off. Once the device die temperature cools by T_J(OFF-HYS), the device turns on and returns to thermal
regulation. Continuous over-temperature conditions result in the pulsing of the load current. If the junction
temperature of the device exceeds T_J(OFF), the charge FET is turned off. The FET is turned back on when the
junction temperature falls below T_J(OFF) – T_J(OFF-HYS).
Note that these features monitor the die temperature of the bq25060. 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.
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