VDD_RTC operation

I would like to know VDD_RTC operation.

(1) Can I connect non rechargerble battery (with diode) to the VDD_RTC ?
ex. Coin Cell(non rechargerble) --> diode --> VDD_RTC

(2) Charger circuit is necessary in outside when I use rechargeable coin cell ?
If need its circuit, do you provide reference circuit to us ?

(3) When is the polarity of the VDD_RTC port switched from output to input?
Always the VDD_RTC is output when the VDD_IN power presents ?

VDD_RTC battery is for RTC part of PMIC, PMIC has internal charger circuit to charge RTC battery when its voltage is lower than system’s. When no system power, the battery/capacitor of VDD_RTC will output to PMIC to maintain RTC work. Non rechargeable cell is not a good idea as its output voltage could drop below the threshold after a long time work without system power input.

PMIC has internal charger circuit ,
Can I connect rechargeable coin cell to the VDD_RTC directly ?

The following types are suitable:

• super capacitor
• standard capacitors (tantalum . . . etc.)
• rechargeable lithium manganese cells