BQ24150 Datasheet, PDF (18/39 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger with Full USB Compliance and USB-OTG Support

bq24150
bq24151
SLUS824 – JUNE 2008 ...................................................................................................................................................................................................... www.ti.com
Input Current Limiting
To maximize the charge rate of bq24150/1 without overloading the USB port, the input current for bq24150/1 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 bq14150, 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 bq24150/1. 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 bq24150/1 monitors the junction temperature,
T_J, of the die and begins to taper down the charge current once T_J reaches the thermal regulation threshold, T_CF.
The charge current is reduced to zero when the junction temperature increases approximately 10°C above T_CF.
At any state, if T_J exceeds T_SHTDWN, bq24150/1 suspends charging. At thermal shutdown mode, PWM is turned
off and all timers are frozen. Charging resumes when T_J falls below T_SHTDWN by approximately 10°C.
Input Voltage Protection in Charge Mode
Sleep Mode
The bq24150/1 enters the low-power sleep mode if the voltage on VBUS pin falls below sleep-mode entry
threshold, V_AUXPWR + V_SLP, and VBUS is still higher than the poor source detection threshold, V_IN(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, bq24150/1 continuously monitors the input voltage, VBUS. If VBUS falls to the low
input voltage threshold, V_IN(min), poor input power source is detected. Under this condition, bq24150/1
terminates the charge process, waits for a delay time of T_INT and repeats the charging process, as indicated in
Figure 23. This unique function provides intelligence to bq24150/1 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 bq24150/1 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, bq24150/1 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 bq24150/1 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, bq24150/1 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 bq24150/1 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, bq24150/1 turns off the
charge and enables a discharge current, I_(DETECT), for a period of t_DETECT, then checks the battery voltage. If the
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