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how long cr2032 battery can backup rtc and ram?

zamzoni
Associate II
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?

2 REPLIES 2
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
Associate II
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...