7.3.3 Short-to-Battery and Reverse Current Detection

Shorting the OUT pin to the battery because of a fault in the system is possible. Each channel detects this failure by comparing the voltage at the OUT and IN pins before the switch turns on. Each time the LDO switch is enabled on the rising edge of the EN pin or during the exiting of the thermal shutdown, the short-to-battery detection occurs. At this moment, if the device detects the short-to-battery fault, the LDO switch is latched off, the ERR pin is asserted low, and the fault-channel SENSE voltage is pulled up internally to a voltage rail between 3.05 V and 3.3 V. The device operates normally when the short-to-battery is removed and the EN pin is toggled.

During normal operation if a short-to-battery fault results in reverse current for more than 5 µs (typical), the LDO switch is latched off and the ERR pin is asserted low. To remove the latched condition after a short-to-battery (reverse current) fault, the condition must first be removed and then the EN pin must be toggled.

Series inductance and the output capacitor can produce ringing during power up or recovery from current limit, resulting in an output voltage that temporarily exceeds the input voltage. The 16-ms (typical) reverse-current blanking can help filter this ringing.

For the dual-channel antenna LDO application, if both channels are enabled and one channel is shorted to ground after power up, the current drawn from the input capacitor can result in a temporary dip in the input voltage, which can trigger the reverse-current detection fault. To avoid this false trigger event, care must be taken when selecting the input capacitor; an increase of the input capacitor value is recommended.