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jaroslaw2
jaroslaw2
Associate III
September 18, 2008
Question

RTC current consumption

  • September 18, 2008
  • 5 replies
  • 1058 views
Posted on September 18, 2008 at 12:11

RTC current consumption

    This topic has been closed for replies.

    5 replies

    jj_it
    jj_it
    Associate II
    May 17, 2011
    Posted on May 17, 2011 at 12:45

    We measured ''in that vicinity'' (always a bit higher) but noted variation with temperature and with Revision.

    When you ask about current consumption with Vdd ON - assume you are speaking of battery drain. (like you - we didn't completely trust and employed a switching xstr. to minimize ''ghost'' load)

    jaroslaw2
    jaroslaw2Author
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 12:45

    Did somebody check true current consumption for battery 3V when RTC is working. In data sheet there is 1.4uA and it is acceptable.

    Second doubt, is current consumption zero when Vdd is connected?

    thanks,

    J.O.

    jaroslaw2
    jaroslaw2Author
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 12:45

    Thanks, that was what I wanted to hear.

    It means that if I have a battery 3V 600mAh. It should last for current 1.4e-6 for:

    600e-3 / 1.4e-6 = 428517 h = 428517/(365*24) = 48 years.

    Am I right :) ?

    best reg.

    J.O.

    [ This message was edited by: jaroslaw.oska on 18-09-2008 09:10 ]

    slawcus
    slawcus
    Associate II
    May 17, 2011
    Posted on May 17, 2011 at 12:45

    I measured a bit below the typ. value.

    jj_it
    jj_it
    Associate II
    May 17, 2011
    Posted on May 17, 2011 at 12:45

    You must consider the ''shelf-life'' of your battery and the life of the STM32s flash. (and any other memory on your board)

    FYI - for an under-water, mini-research project we used 2 3V lithium batteries and electrically alternated them. This was clearly ''overkill'' - sometimes client ''comfort'' is not entirely logical...

    [ This message was edited by: jj.sprague on 18-09-2008 16:05 ]

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