We use a 3.3V regulator as VBAT in our product. When the product is powered off regulator is off and there is no power on VBAT. A 3V backup battery connected to BKBAT pin H9 keeps the Real Time Clock going in backup mode. I noticed that normally the 1.8V VIO (pins P4 and N4) is up in about 4mSec but when the backup battery is lower than 2.6V it takes 280mSec for the 1.8V to become available. Another abnormality is the TSC2006 touchscreen controller which uses the 1.8V VIO as its power source, does not function when this backup battery is below 2.6V.
Is it acceptable to run the TPS65930 with an axternal regulator?
What happens when the regulator is powered up and the backup battery is below 2.6V?
Thank you
Fuad