BQ24190_15 Datasheet, PDF (16/52 Pages) Texas Instruments – bq2419x I2C Controlled 4.5-A Single Cell USB/Adapter Charger with Narrow VDC Power Path Management and USB OTG

bq24190, bq24192, bq24192I
SLUSAW5B – JANUARY 2012 – REVISED DECEMBER 2014
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A type III compensation network allows using ceramic capacitors at the output of the converter. An internal saw-
tooth ramp is compared to the internal error control signal to vary the duty cycle of the converter. The ramp
height is proportional to the PMID voltage to cancel out any loop gain variation due to a change in input voltage.
In order to improve light-load efficiency, the device switches to PFM control at light load when battery is below
minimum system voltage setting or charging is disabled. During the PFM operation, the switching duty cycle is
set by the ratio of SYS and VBUS.
9.3.1.5 Boost Mode Operation from Battery
The bq24190, bq24192, bq24192I supports boost converter operation to deliver power from the battery to other
portable devices through USB port. The boost mode output current rating meets the USB On-The-Go 500-mA
output requirement. The maximum output current is 1.3 A. The boost operation can be enabled if the following
conditions are valid:
1. BAT above BATLOWV threshold (V_BATLOWV set by REG04[1])
2. VBUS less than BAT+V_SLEEP (in sleep mode)
3. Boost mode operation is enabled (OTG pin HIGH and REG01[5:4] = 10)
4. After 220-ms delay from boost mode enable
In boost mode, the bq24190, bq24192, bq24192I employs a 1.5-MHz step-up switching regulator. Similar to buck
operation, the device switches from PWM operation to PFM operation at light load to improve efficiency.
During boost mode, the status register REG08[7:6] is set to 11, the VBUS output is 5 V and the output current
can reach up to 500 mA or 1.3 A, selected via I²C (REG01[0]).
Any fault during boost operation, including VBUS over-voltage or over-current, sets the fault register REG09[6] to
1 and an INT is asserted.
9.3.2 Power Path Management
The bq24190, bq24192, bq24192I accommodates a wide range of input sources from USB, wall adapter, to car
battery. The device provides automatic power path selection to supply the system (SYS) from input source
(VBUS), battery (BAT), or both.
9.3.2.1 Narrow VDC Architecture
The device deploys Narrow VDC architecture (NVDC) with BATFET separating system from battery. The
minimum system voltage is set by REG01[3:1]. Even with a fully depleted battery, the system is regulated above
the minimum system voltage (default 3.5 V).
When the battery is below minimum system voltage setting, the BATFET operates in linear mode (LDO mode),
and the system is 150 mV above the minimum system voltage setting. As the battery voltage rises above the
minimum system voltage, BATFET is fully on and the voltage difference between the system and battery is the
V_DS of BATFET.
When the battery charging is disabled or terminated, the system is always regulated at 150 mV above the
minimum system voltage setting. The status register REG08[0] goes high when the system is in minimum system
voltage regulation.
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