Posted on May 17, 2011 at 12:15next question what happens if there is an input signal (+5 volt compatible) [ push button with resistor to VBAT] that is attached to the VBAT supply and then VDD is turned off. Does the input start draining the VBAT? N...

Posted on May 17, 2011 at 12:15From AN2586 Battery backup To retain the content of the Backup registers when VDD is turned off, the VBAT pin can be connected to an optional standby voltage supplied by a battery or another source. The VBAT pin also p...