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LSE vs LSI for periodic wakeup from Stop

DOCon.1
Senior

Does LSE have any power-saving advantages over LSI when the RTC is used to periodically wake up from low-power modes? Or does it just provide better accuracy for the RTC?

For example, let's say you only use the RTC to wake up from stop mode, but never check the time and date: would you use an LSE, or LSI? Thank you.

Tangent: Do you need to manually disable (then later re-enable) peripheral clocks (like those in apb1 and ahb) to maximize power saving, or is that done automatically by `stop`? The RM implies it `gates` peripheral clocks, but I'm curious if I should be manually turning off and on each one. Or perhaps you only need to manually disable/re-enable ones listed on the low power supporting documents (like AN4621) as being avail for a given low-power mode? So in L4 Stop2, maybe you need to disable I2C3 if you used it, but not the timers.

1 ACCEPTED SOLUTION

Accepted Solutions
Mohamed Aymen HZAMI
ST Employee

Hello @DOCon.1​

The LSE clock accuracy is better than the LSI and for the power consumption the LSE Quartz in low drive mode is better than the LSE Bypass or LSI, you can check this in the datasheet table 44 ( Current consumption in Stop 2 mode, SRAM3 disabled).

Mohamed Aymen.

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2 REPLIES 2
Mohamed Aymen HZAMI
ST Employee

Hello @DOCon.1​

The LSE clock accuracy is better than the LSI and for the power consumption the LSE Quartz in low drive mode is better than the LSE Bypass or LSI, you can check this in the datasheet table 44 ( Current consumption in Stop 2 mode, SRAM3 disabled).

Mohamed Aymen.

DOCon.1
Senior

Thank you