how long cr2032 battery can backup rtc and ram?

[zamzoni]

Posted on March 02, 2013 at 15:01

If I attach cr2032 battery to STM32F103RBT6, how long it can run the rtc and backup the content of ram?

[waclawek.jan]

Posted on March 02, 2013 at 15:34

As the self-discharge of lithium primary cells is negligible, simply divide the cell's capacity (cca 225mAh) by the RTC's current consumption (see datasheet).

JW

[jj2]

Posted on March 03, 2013 at 23:09

And - should either the MCU or external circuit be sufficiently clever - you likely can avoid any such battery drain while the ''main'' power is supplied. 

Depending upon power-on vs power-off duty cycle - this may/may not be a big deal...