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BQ24157S Datasheet, PDF (16/45 Pages) Texas Instruments – Full USB Compliance and USB-OTG Support
Not Recommended for New Designs
bq24157S
SLUSB76B – FEBRUARY 2013 – REVISED MAY 2015
Feature Description (continued)
Charge Command
(Host Control or VBUS
Ramps Up)
Delay 10mS
Enable Adaptor Detection
Start 30ms Timer
Enable Input Current Sink
(30mA, to GND)
No
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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 21. Bad Adaptor Detection Scheme Flow Chart
8.3.1.3 Sleep Mode
The IC enters the low-power sleep mode if the VBUS pin voltage falls below the sleep-mode entry threshold,
VCSOUT + VSLP, and VBUS is higher than the bad adaptor 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.
8.3.1.4 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. After the VBUS drops to VIN_DPM (default 4.52 V), 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.
8.3.2 Battery Protection
8.3.2.1 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. When V(CSOUT) drops to the battery overvoltage exit threshold, the fault is cleared and the charge process
resumes.
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