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STM32L151 stop mode with RTC, 4uA current draw?

Question asked by abdeen.faizal.001 on Jul 21, 2016
Latest reply on Jul 21, 2016 by Nesrine M
We use stm32l151ccu6 with RTC clocked by LSI. The device is set to wake up, every 20 seconds,  from stop mode using the RTC auto wakeup feature. At present, the device just goes back to stop mode after clearing the RTC_WUF flag. This is all well and good. I find the current consumption profile somewhat puzzling.

Current draw in stop mode + RTC before first wakeup = ~2uA. This is perfectly acceptable. Note that RTC is active, and is counting towards the first wakeup.

After first wakeup and subsequent stop modes, the current draw jumps to  4uA.

What is causing the extra 2uA? I only see this with the RTC. When PA0 is configured for wakeup, and RTC is not enabled, current draw stays at 2uA at all times in STOP mode regardless of the number of wakeups.

Any insight is much appreciated!

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