Texas Instruments BQ2419X I²C Controlled 4.5A Single Cell USB / Adaptor Charger Evaluation Module BQ24195LEVM-193 BQ24195LEVM-193 Datenbogen
Produktcode
BQ24195LEVM-193
SLUSB97 – OCTOBER 2012
In default mode, the charger IC will reset REG00[7] back to 0 when input source is removed. When another
source plugs in, the charger IC will run detection again, and update the input current limit.
source plugs in, the charger IC will run detection again, and update the input current limit.
Force Input Current Limit Detection
The host can force the charger device to run input current limit detection by setting REG07[7]=1. After the
detection is complete, REG07[7] will return to 0 by itself.
detection is complete, REG07[7] will return to 0 by itself.
Converter Power-Up
After the input current limit is set, the converter is enabled and the HSFET and LSFET start switching. If battery
charging is disabled, BATFET turns off. Otherwise, BATFET stays on to charge the battery.
charging is disabled, BATFET turns off. Otherwise, BATFET stays on to charge the battery.
The bq24195L, bq24195 provides soft-start when ramp up the system rail. When the system rail is below 2.2V,
the input current limit is forced to 100mA. After the system rises above 2.2V, the charger device sets the input
current limit set by the lower value between register and ILIM pin.
the input current limit is forced to 100mA. After the system rises above 2.2V, the charger device sets the input
current limit set by the lower value between register and ILIM pin.
As a battery charger, the bq24195L, bq24195 deploys a 1.5MHz step-down switching regulator. The fixed
frequency oscillator keeps tight control of the switching frequency under all conditions of input voltage, battery
voltage, charge current and temperature, simplifying output filter design.
frequency oscillator keeps tight control of the switching frequency under all conditions of input voltage, battery
voltage, charge current and temperature, simplifying output filter design.
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.
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.
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.
Boost Mode Operation from Battery
The bq24195L, bq24195 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 1A (bq24195L) or 2.1A (bq24195)
charging requirements for smartphone and tablet. The boost operation can be enabled if the following conditions
are valid:
devices through USB port. The boost mode output current rating meets the 1A (bq24195L) or 2.1A (bq24195)
charging requirements for smartphone and tablet. 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 220ms delay from boost mode enable
In battery boost mode, the bq24195L, bq24195 employs a 1.5MHz step-up switching regulator. During boost
mode, the status register REG08[7:6] is set to 11, the PMID output voltage is 5.1V.
mode, the status register REG08[7:6] is set to 11, the PMID output voltage is 5.1V.
For power bank applications, the boost current is supported from PMID pin as in the application diagram. It is
recommended to use the minimum PMID cap value 20uF (bq24195L) or 60uF (bq24195) for boost current.
Please note that there is no boost current limit setting when the boost current is sourced from PMID pin, hence it
is important not to overload the boost current under this condition.
recommended to use the minimum PMID cap value 20uF (bq24195L) or 60uF (bq24195) for boost current.
Please note that there is no boost current limit setting when the boost current is sourced from PMID pin, hence it
is important not to overload the boost current under this condition.
Power Path Management
The bq24195L, bq24195 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.
The device provides automatic power path selection to supply the system (SYS) from input source (VBUS),
battery (BAT), or both.
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 3.5V).
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 3.5V).
When the battery is below minimum system voltage setting, the BATFET operates in linear mode (LDO mode),
and the system is 150mV 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
and the system is 150mV 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.
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