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STM32F4107VG6 silicon rev. 1 - LSE don't start at low temp

olg
Associate
Posted on December 01, 2015 at 17:27

Hi !

I'm just wondering if anybody have seen similar behaviour with LSE on revision ''1'' silicon of  STM32F4107VG6.

LSE starts perfectly at room temp but fails to start completely at temps below -15 celsius.

Load capacitors and oscillator selection was  done strictly according to application note.

We started experience this behaviour on silicon revision ''1'' chips. On previous silicon revision ''Z'' everything was ok.

BR,

Oleg
2 REPLIES 2
gkennerknecht
Associate II
Posted on December 01, 2015 at 17:32

Hi,

have a look at the BootPins. We have a similar Problemn with STM32F105VCT6.

In case of low Temperatures (below -15°C) the Micro doesn´t ''start''. But it´s  a wrong Interpretation. We missed to tie the Boot Pins to gnd.

After pinning the Pins to gnd, Startup from Flash works at temperatures down to -40°C.

We think that the Boot Pins are floating at low temperatures and in some cases the Startup jumps to SRAM.

Bye

Posted on December 01, 2015 at 19:12

The STM32 parts are very sensitive to the characteristics/gain of the LSE component/circuit implementation. It can result in very slow starting, or non-starting of the crystal, but this should be demonstrably different from it not executing any code. ie you should be able to output diagnostics via a USART or GPIO/LED, to identify it is running normally, and then attempting to start the LSE. Neither crystal is started automatically, which makes signs-of-life testing of free standing STM32 quite difficult.

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