BQ24157 Datasheet, PDF (17/39 Pages) Texas Instruments – Fully Integrated Switch-Mode Charger With USB Compliance and USB-OTG Support

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Charge Command
(Host Control or VBUS
Ramps Up)
Delay 10mS
Enable Adaptor Detection
Start 30ms Timer
Enable Input Current Sink
(30mA, to GND)
No
bq24157
SLUSB80 – SEPTEMBER 2012
VBUS>VIN(MIN)?
Yes
30ms Timer
Expired?
No
Bad Adaptor Detected
Pulsing STAT Pin
Set Bad Adaptor Flag
Yes
Good Adaptor Detected
Disable Adaptor Detection
Charge Start
Enable VIN Based DPM
Delay TINT
(2 Seconds)
Figure 26. Bad Adaptor Detection Scheme Flow Chart
Sleep Mode
The IC enters the low-power sleep mode if the VBUS pin voltage falls below the sleep-mode entry threshold,
V_CSOUT+V_SLP, and VBUS is higher than the bad adaptor detection threshold, V_IN(MIN). This feature prevents
draining the battery during the absence of V_BUS. During sleep mode, both the reverse blocking switch Q1 and
PWM are turned off.
Input Voltage Based DPM (Special Charger Voltage Threshold)
During the charging process, if the input power source is not able to support the programmed or default charging
current, the VBUS voltage will decrease. Once the VBUS drops to V_{IN_DPM} (default 4.52V), the charge current
begins to taper down to prevent any further drop of VBUS. When the IC enters this mode, the charge current is
lower than the set value and the special charger bit is set (B4 in Register 05H). This feature makes the IC
compatible with adapters having different current capabilities.
BATTERY PROTECTION
Output Overvoltage Protection
The IC 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, the IC turns off the PWM converter, sets fault status bits, and sends out a fault pulse from the STAT
pin. Once V_(CSOUT) drops to the battery overvoltage exit threshold, the fault is cleared and charge process
resumes.
Copyright © 2012, Texas Instruments Incorporated
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