STM32L151 LSI clock accuracy

[yarona]

Posted on August 12, 2015 at 10:54

Hi

RM0038 Reference manual sais: ''LSI clock ... The clock frequency is around37 kHz.''Can you tell me what is the max possible clock Deviation? (in percentage / Hz)ThanksYaron #stm32

[waclawek.jan]

Posted on August 12, 2015 at 11:11

It's in the datasheet.

The idea is, that the RM contains information on ''how it works'' from the logical point of view and the datasheet information on physical particularities. JW

[Nesrine M_O]

Posted on August 12, 2015 at 11:33

Hi Yaron,

I suggest you to check the LSI oscillator characteristics table in the related datasheet of your STM32 product.-Syrine-

[yarona]

Posted on August 12, 2015 at 11:42Hi Thanks for your responses.from the datasheet i see that LSI oscillator frequency drift is -10 to +4 %.however, the actual parameter i am looking for is the drift rate. (in my application i am more sensetive for the drift and not the accuracy).Is there a specification for the drift per hour/day....Yaron

[John F.]

Posted on August 12, 2015 at 12:32

-10% .. +4% is a deviation for an individual part, once the initial frequency has been measured.

It applies over the temperature range 0 degrees C .. 105 degrees C. Temperature is the most likely short term cause of variation and note its effect

may not be linear

. Only you will know what the expected temperature variation is for your application. (Alternatively, thermostat the device or don't use the LSI oscillator.)

[Tesla DeLorean]

Posted on August 12, 2015 at 15:20

I'm not even sure characterizing a given part over temperature and voltage is going to help, but might be worth evaluating just to see how bad it is.

With F1/2/4 I'm pretty sure it's wildly unstable with static conditions. The latter parts can time the periodicity (1, 2, or 8 cycles) against solid external sources.

[Nesrine M_O]

Posted on August 12, 2015 at 15:37

Hi Yaron,

Please check with your FAE or local representative to get more details on the drift rate.-Syrine-