BQ24157S Datasheet, PDF (15/45 Pages) Texas Instruments – Full USB Compliance and USB-OTG Support

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bq24157S
SLUSB76B – FEBRUARY 2013 – REVISED MAY 2015
8.3 Feature Description
8.3.1 Input Voltage Protection
8.3.1.1 Input Overvoltage Protection
The IC provides built-in input overvoltage protection to protect the device and other components against damage
if the input voltage (voltage from VBUS to PGND) goes too high. When an input 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_BUS drops below the input overvoltage exit threshold, the fault is cleared and the charge process
resumes.
8.3.1.2 Bad Adaptor Detection/Rejection
Although not shown in Figure 20, at power-on-reset (POR) of VBUS, the IC performs the bad adaptor detection
by applying a current sink to VBUS. If the VBUS is higher than V_IN(MIN) for 30 ms, the adaptor is good and the
charge process begins. If the VBUS drops below V_IN(MIN), a bad adaptor is detected. Then, the IC disables the
current sink, sends a send fault pulse in FAULT pin, and sets the bad adaptor flag (B2 – B0 = 011 for register
00H). After a delay of T_INT, the IC repeats the adaptor detection process, as shown in Figure 20 and Figure 21.
Adpator
VBUS
VBUS
I_SHORT
(30 mA)
Adaptor Detection Control
GND
PGND
V_IN
V_IN(MIN)
V_{IN_GOOD}
Deglitch
30ms
V_{IN_POOR}
START
Delay
T_INT
Figure 20. Bad Adaptor Detection Circuit
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