BQ24196_17 Datasheet, PDF (22/50 Pages) Texas Instruments – I2C Controlled 2.5-A Single Cell USB/Adapter Charger with Narrow VDC Power Path Management and USB OTG

bq24196
SLUSB98A – OCTOBER 2012 – REVISED DECEMBER 2014
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For example, if the ILIM pin sets 2 A, and the ILIM voltage is 0.6 V, the actual input current is 1.2 A. If the ILIM
pin is open, the input current is limited to zero since ILIM voltage floats above 1 V. If the ILIM pin is short, the
input current limit is set by the register.
8.3.5.2 Thermal Regulation and Thermal Shutdown
The bq24196 monitors the internal junction temperature T_J to avoid overheat the chip and limits the IC surface
temperature. When the internal junction temperature exceeds the preset limit (REG06[1:0]), the device lowers
down the charge current. The wide thermal regulation range from 60°C to 120°C allows the user to optimize the
system thermal performance.
During thermal regulation, the actual charging current is usually below the programmed battery charging current.
Therefore, termination is disabled, the safety timer runs at half the clock rate, and the status register REG08[1]
goes high.
Additionally, the device has thermal shutdown to turn off the converter. The fault register REG09[5:4] is 10 and
an INT is asserted to the host.
8.3.5.3 Voltage and Current Monitoring in Buck Mode
The bq24196 closely monitor the input and system voltage, as well as HSFET and LSFET current for safe buck
mode operation.
8.3.5.3.1 Input Over-Voltage (ACOV)
The maximum input voltage for buck mode operation is 18 V. If VBUS voltage exceeds 18 V, the device stops
switching immediately. During input over voltage (ACOV), the fault register REG09[5:4] will be set to 01. An INT
is asserted to the host.
8.3.5.3.2 System Over-Voltage Protection (SYSOVP)
The charger device monitors the voltage at SYS. When system over-voltage is detected, the converter is stopped
to protect components connected to SYS from high voltage damage.
8.3.5.4 Voltage and Current Monitoring in Boost Mode
The bq24196 closely monitors the VBUS voltage, as well as HSFET and LSFET current to ensure safe boost
mode operation.
8.3.5.4.1 VBUS Over-Voltage Protection
The boost mode regulated output is 5 V. When an adapter plugs in during boost mode, the VBUS voltage will
rise above regulation target. Once the VBUS voltage exceeds 5.3 V, the bq24196 stops switching and the device
exits boost mode. The fault register REG09[6] is set high to indicate fault in boost operation. An INT is asserted
to the host.
8.3.5.5 Battery Protection
8.3.5.5.1 Battery Over-Current Protection (BATOVP)
The battery over-voltage limit is clamped at 4% above the battery regulation voltage. When battery over voltage
occurs, the charger device immediately disables charge. The fault register REG09[5] goes high and an INT is
asserted to the host.
8.3.5.5.2 Charging During Battery Short Protection
If the battery voltage falls below 2 V, the charge current is reduced to 100 mA for battery safety.
8.3.5.5.3 System Over-Current Protection
If the system is shorted or exceeds the over-current limit, the BATFET is latched off. DC source insertion on
VBUS is required to reset the latch-off condition and turn on BATFET.
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