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BQ24150A Datasheet, PDF (18/41 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger With Full USB Compliance and USB-OTG Support
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bq24150A
bq24151A
SLUS931 – APRIL 2009 ..................................................................................................................................................................................................... www.ti.com
Input Current Limiting
To maximize the charge rate of bq24150A/1A without overloading the USB port, the input current for
bq24150A/1A can be limited to 100mA or 500mA which is programmed in the control register or OTG pin. Once
the input current reaches the input current limiting threshold, the charge current is reduced to keep the input
current from exceeding the programmed threshold. For bq24150A, the default input current limit is controlled by
the OTG pin at VBUS power on reset when V(AUXPWR) is lower than V(LOWV). The input current sensing resistor
and control loop are integrated into bq24150A/1A. The input current limit can also be disabled using I2C control,
see the definition of control register (01H) for details.
Thermal Regulation and Protection
To prevent overheating the chip during the charging process, the bq24150A/1A monitors the junction
temperature, TJ, of the die and begins to taper down the charge current once TJ reaches the thermal regulation
threshold, TCF. The charge current is reduced to zero when the junction temperature increases approximately
10°C above TCF. At any state, if TJ exceeds TSHTDWN, bq24150A/1A suspends charging. At thermal shutdown
mode, PWM is turned off and all timers are frozen. Charging resumes when TJ falls below TSHTDWN by
approximately 10°C.
Input Voltage Protection in Charge Mode
Sleep Mode
The bq24150A/1A enters the low-power sleep mode if the voltage on VBUS pin falls below sleep-mode entry
threshold, VAUXPWR + VSLP, and VBUS is still higher than the poor source detection threshold, VIN(min). This
feature prevents draining the battery during the absence of VBUS. During sleep mode, both the reverse blocking
switch Q1 and PWM are turned off.
Input Source Detection
During the charging process, bq24150A/1A continuously monitors the input voltage, VBUS. If VBUS falls to the
low input voltage threshold, VIN(min), poor input power source is detected. Under this condition, bq24150A/1A
terminates the charge process, waits for a delay time of TINT and repeats the charging process, as indicated in
Figure 23. This unique function provides intelligence to bq24150A/1A and so prevents USB power bus collapsing
and oscillation when connecting to a suspended USB port, or a USB-OTG device with low current capability.
Input Overvoltage Protection
The bq24150A/1A provides a built-in input over-voltage protection to protect the device and other components
against damages if the input voltage (Voltage from VBUS to PGND) goes too high. When an input overvoltage
condition is detected, bq24150A/1A turns off the PWM converter, sets fault status bits, and sends out fault pulse
in STAT pin. Once VBUS drops below the input overvoltage exit threshold, the fault is cleared and charge
process resumes.
Battery Protection in Charge Mode
Output Overvoltage Protection
The bq24150A/1A provides a built-in overvoltage protection to protect the device and other components against
damage if the battery voltage goes too high, as when the battery is suddenly removed. When an overvoltage
condition is detected, bq24150A/1A turns off the PWM converter, sets fault status bits and sends out fault pulse
in STAT pin. Once V(CSOUT) drops to the battery overvoltage exit threshold, the fault is cleared and charge
process back to normal.
Battery Detection During Normal Charging
For applications with removable battery packs, the bq24150A/1A provides a battery absent detection scheme to
reliably detect insertion or removal of battery packs.
During normal charging process with host control, once the voltage at the AUXPWR pin is above the battery
recharge threshold, V(OREG) – V(RCH), and the termination charge current is detected, bq24150A/1A turns off the
charge and enables a discharge current, I(DETECT), for a period of tDETECT, then checks the battery voltage. If the
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