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STM32F103 ADC supply config

Question asked by khashayar fathinejad on Apr 15, 2018
Latest reply on Apr 18, 2018 by T J

Hi to all

datasheet 13587 Rev 17

5.3.1 table 9 says: Vdda must be same potential as Vdd with a maximum diff of 300mV (footnote).

5.3.18 table 46 says: Vdda must be between 2.4 - 3.6 and not mentioning anything about Vdd

and  AN2834 2.2.12 says: it is desirable to have separate analog and digital supplies. 
so the question is: how can i manage Vdda - Vdd <= 300mV with different supplies during opration and especially during power up?

 

and 2 other question about Vref,

 

AN2834 suggests using linear regulators but usually they have errors in different temperatures,do you suggest using reference voltage ICs?

 

also about using a separate 3.3v voltage reference ic for Vref: in table 46 of datasheet max rate for Vref is mentioned Vdda, and using different 3.3 supplies doesn't guaranty exact same 3.3000 voltage for both Vref and VDDa, is this difference going to be a problem or can i forget about it?

my supply is: SMPS DCtoDC 12-5 and in next level two separate LDOreg 5-3.3 for Vdda and Vdd.

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