BQ24190_15 Datasheet, PDF (23/52 Pages) Texas Instruments – bq2419x I2C Controlled 4.5-A Single Cell USB/Adapter Charger with Narrow VDC Power Path Management and USB OTG

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bq24190, bq24192, bq24192I
SLUSAW5B – JANUARY 2012 – REVISED DECEMBER 2014
When a fault occurs, the charger device sends out INT and keeps the fault state in REG09 until the host reads
the fault register. Before the host reads REG09 and all the faults are cleared, the charger device would not send
any INT upon new faults. In order to read the current fault status, the host has to read REG09 two times
consecutively. The 1^st reads fault register status from the last read and the 2^nd reads the current fault register
status.
9.3.5 Protections
9.3.5.1 Input Current Limit on ILIM
For safe operation, the bq24190, bq24192, bq24192I has an additional hardware pin on ILIM to limit maximum
input current on ILIM pin. The input maximum current is set by a resistor from ILIM pin to ground as:
1V
I_INMAX = _RILIM ´ 530
(3)
The actual input current limit is the lower value between ILIM setting and register setting (REG00[2:0]). For
example, if the register setting is 111 for 3 A, and ILIM has a 353-Ω resistor to ground for 1.5 A, the input current
limit is 1.5 A. ILIM pin can be used to set the input current limit rather than the register settings.
The device regulates ILIM pin at 1 V. If ILIM voltage exceeds 1 V, the device enters input current regulation
(Refer to Dynamic Power Path Management section).
The voltage on the ILIM pin is proportional to the input current. The ILIM pin can be used to monitor the input
current per Equation 4:
IIN
=
V_ILIM
1V
´ I_INMAX
(4)
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.
9.3.5.2 Thermal Regulation and Thermal Shutdown
The bq24190, bq24192, bq24192I 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.
9.3.5.3 Voltage and Current Monitoring in Buck Mode
The bq24190, bq24192, bq24192I closely monitor the input and system voltage, as well as HSFET and LSFET
current for safe buck mode operation.
9.3.5.3.1 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.
9.3.5.3.2 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.
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