Low power operation for STM32L4xx devices

Mikexx · ‎2018-03-02

Posted on March 03, 2018 at 01:22

This is for shutdown power consumption.

Table 5 of AN4621 says '8 nA w/o RTC' and '260 nA w/ RTC'

Table 37 in STM32L443xC datasheet - en.DM00254865.pdf (July 2017) says 8nA and 25nA for the same conditions.

Something feels very wrong in one of these tables.

Table also says at 3.6V it says 212nA is typical at 25C and 119nA maximum at 25C. This is clearly wrong and its not obvious which item.

There are 5 active wake-up pins, I can't find any details of their preferred levels whilst in shutdown? Is there any?

Are there any further gotchas, or things I should note?

I would apprciate anyone's experience and guidance.

RomainR. · ‎2018-03-03

Posted on March 03, 2018 at 19:27

Hi Mike xx

Concerning Wake up Pin configuration.

See Power control register 3 (PWR_CR3) and PWR_CR4 in Reference Manual Chapter 5

Same for all dedicated wakeup pin

Bit 4 EWUP5: Enable Wakeup pin WKUP5 When this bit is set, the external wakeup pin WKUP5 is enabled and triggers a wakeup from Standby or Shutdown event when a rising or a falling edge occurs.The active edge is configured via the WP5 bit in the PWR_CR4 register.

All pin are configurable on rising or falling edge (for wake)

KR

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Mikexx · ‎2018-03-03

Posted on March 03, 2018 at 23:14

Many thanks, I can see the Wake-up pins and the efect of a tranition is controlled by PWR_CR3.

My post was more about the best electrical conditions should be for unused wake-up pins. I don't have room for external resistors but would be happy to tie these unused pins to ground. I presume they shouldn't be left floating?