ZHCS688I November 2011 – March 2018 TPS65217
PRODUCTION DATA.
The AC or USB inputs are valid and the device powers up if the AC or USB input voltage increases above 4.3 V. After powering up, the input voltage can decrease to a value of VUVLO + VOFFSET (for example, 3.3 V + 200 mV) before the device powers down.
The AC input is prioritized over the USB input; that is, if both inputs are valid, current is pulled from the AC input and not the USB input. If both AC and USB supplies are available, the power-path switches to the USB input if AC voltage decreases to less than 4.1 V (fixed threshold).
NOTE
The rise time of the AC and USB input voltage must be less than 50 ms for the detection circuits to operate correctly. If the rise time is longer than 50 ms, the device may fail to power up.
The linear charger periodically applies a 10-mA current source to the BAT pin to check for the presence of a battery. This applied current causes the BAT pin to float up to more than 3 V, which may interfere with AC removal detection and prevent switching from the AC to the USB input. For this reason, TI does not recommend using both the AC and USB inputs when the battery is absent.