I can get two information about backup battery voltage range in TX2 module datasheet.
What is the supply voltage range(especially minimum voltage) of a backup battery that RTC circuit can keep the time information?
Ref : Jetson_TX2_TX2i_Module_DataSheet_v1.2.pdf
2.5 ~ 3.5 V
3.1 Power Rails
VDD_RTC is connected directly to the onboard PMIC. Backup cells must provide a voltage in the range 2.5V to 3.5V.
1.65 ~ 5.5 V
6.2 Recommended Operating Conditions
Parameter Min Typical Max Unit Notes
VDD_RTC 1.65 5.5 V TX2 / TX2i / TX2 4GB