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I've just searched for a suitable ultra low power design that is supposed to provide me 3V and only 10uA load from input 2...3V. It's quiescent must be reasonable low <10uA too.

One solution will be LTC3221 but it's quite expensive as all Linear circuits.

I have a MCU that have 32KHz crystalk in place, running all the time. One idea is to rectify that wave and use a low Iq LDO.

Any thoughts? Thank you.

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    \$\begingroup\$ I think loading that crystal is a bad idea, but most uC's can route some timer output to a pin, or you could bit-bang a square wave to one or two (anti-phase) outputs. \$\endgroup\$ Commented Sep 26, 2015 at 18:44

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Why not program 2 of the microprocessor outputs to make a couple of out of phase square waves .These could be diode pumped to give 3V pK pK minus diode drops .This DC volts is put in series with your existing Batt pos input of 2 to 3 V.Now you have more than enough to pass it through a low drop linear reg thats specified to output 3 V.Your caps wont be big for 10 microamp.

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  • \$\begingroup\$ Yes I know, but MCU is sleeping most of the times. I need this for powering a sensor that is supposed to wakeup the MCU. It's 32.768 secondary osc will runn all the times. \$\endgroup\$ Commented Sep 29, 2015 at 6:08

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