I have connected a battery to ball G9 BKBAT VBACKUP and have maintained the RTC after removing power main power VBAT.
The documentation on the TPS65921 states that ball G9 BKBAT VBACKUP must be shorted to GND, yet the documenation also states the VRTC.OUT output voltage range for both "Normal mode" and "Backup mode".
The "Differences in Features for TPS65920 and TPS65921" states that the "Backup battery charger feature removed".
Could it be that only the backup battery charger feature was removed and not backup battery feature so the RTC can be maintained via ball G9 BKBAT VBACKUP ?
Thanks,
Jeff