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Paul Jon
Paul Jon
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If one wants to build a build a ludicrously low power rtc, i highly recommend AMBIQs line of RTCs (Artasie line). I2C or SPI, ~256 bytes of user RAM, two alarms (as far as I know), built in oscillators (two, if I recall correctly) and a current consumption of ~ 70 nW with autocalibration active / 50 without it.

Yep Yep. Nanowatts. VDD 1.5V - 3.6V. Another nice feature is a built-in low side switch, so you connect the RTC to your battery's - and the rest of your board to the RTC's other gnd pin. And, when commanded, the RTC will essentially cut the power to the rest of your design, bringing the total power consumption in the very low nanoamps range.

[The following are really basic calculations, not considering voltage curves, etc. but you get the gist]

A typical primary lithium battery 3V CR2032 holds ~ 225 mAh worth of juice. It has a self discharge rate of roughly 1% per annum. The RTC burns through 70×24×365,24 nW per year. So you could easily power such a device for more than 100 years. I mean you could: solar, kinetic, thermal, rf harvesting etc. But what would be the point? :)

If one wants to build a build a ludicrously low power rtc, i highly recommend AMBIQs line of RTCs (Artasie line). I2C or SPI, ~256 bytes of user RAM, two alarms (as far as I know), built in oscillators (two, if I recall correctly) and a current consumption of ~ 70 nW with autocalibration active / 50 without it.

Yep. Nanowatts. VDD 1.5V - 3.6V. Another nice feature is a built-in low side switch, so you connect the RTC to your battery's - and the rest of your board to the RTC's other gnd pin. And, when commanded, the RTC will essentially cut the power to the rest of your design, bringing the total power consumption in the very low nanoamps range.

[The following are really basic calculations, not considering voltage curves, etc. but you get the gist]

A typical primary lithium battery 3V CR2032 holds ~ 225 mAh worth of juice. It has a self discharge rate of roughly 1% per annum. The RTC burns through 70×24×365,24 nW per year. So you could easily power such a device for more than 100 years. I mean you could: solar, kinetic, thermal, rf harvesting etc. But what would be the point? :)

If one wants to build a build a ludicrously low power rtc, i highly recommend AMBIQs line of RTCs (Artasie line). I2C or SPI, ~256 bytes of user RAM, two alarms (as far as I know), built in oscillators (two, if I recall correctly) and a current consumption of ~ 70 nW with autocalibration active / 50 without it. Yep. Nanowatts. VDD 1.5V - 3.6V.

[The following are really basic calculations, not considering voltage curves, etc. but you get the gist]

A typical primary lithium battery 3V CR2032 holds ~ 225 mAh worth of juice. It has a self discharge rate of roughly 1% per annum. The RTC burns through 70×24×365,24 nW per year. So you could easily power such a device for more than 100 years. I mean you could: solar, kinetic, thermal, rf harvesting etc. But what would be the point? :)

Source Link
Paul Jon
Paul Jon
  • 43
  • 7

If one wants to build a build a ludicrously low power rtc, i highly recommend AMBIQs line of RTCs (Artasie line). I2C or SPI, ~256 bytes of user RAM, two alarms (as far as I know), built in oscillators (two, if I recall correctly) and a current consumption of ~ 70 nW with autocalibration active / 50 without it.

Yep. Nanowatts. VDD 1.5V - 3.6V. Another nice feature is a built-in low side switch, so you connect the RTC to your battery's - and the rest of your board to the RTC's other gnd pin. And, when commanded, the RTC will essentially cut the power to the rest of your design, bringing the total power consumption in the very low nanoamps range.

[The following are really basic calculations, not considering voltage curves, etc. but you get the gist]

A typical primary lithium battery 3V CR2032 holds ~ 225 mAh worth of juice. It has a self discharge rate of roughly 1% per annum. The RTC burns through 70×24×365,24 nW per year. So you could easily power such a device for more than 100 years. I mean you could: solar, kinetic, thermal, rf harvesting etc. But what would be the point? :)