About the negative ref voltage supply to STM32H753ZI

[RongShengWang]

Hi,

    The datasheets says (P173) - the VREF– s available only on UFBGA176+25 and
TFBGA240+25. When VREF- is not available, it is internally connected to VDDA and VSSA.

 Our ADC input signal goes to both positive and negative. 

Questions:

1. What the part number we should use, which allows VREF–? (Negative ref)

2. Is VREF– a fixed value or changeable? How is it defined relative to the input signal range?

3. Does NUCLEO-H753ZI board allow our negative ADC input signal in? If so, who is the the range (max + and max -) defined? 

Thank you very much for your help,

 

[jiangfan]

Refer to chapter 9 Ordering information, for part number with VREF-

[RongShengWang]

Thanks

"Refer to chapter 9" - In which document? 

Thanks again

[jiangfan]

datasheet

[jiangfan]

VREF+ max is Vdda (Max 3.6V), so, I suppose VREF- min is -3.6V

[RongShengWang]

Thanks,

“VREF+ max is Vdda (Max 3.6V), so, I suppose VREF- min is -3.6V”

What is VREF+ min ？

What is VREF- max?

Also -

Can the input signals on their selected channels of all SAR ADC be sampled synchronously under the same sampling rate?

Thanks again

 

 

[jiangfan]

refer to chapter 6.3.20 of datasheet

[jiangfan]

if understand correctly, NUCLEO-H753ZI board does not support negative ADC input if ADC input directly connected to STM32H753ZI pin. User may use OPAMP to shift negative input ~ positive input => 0 ~ Vdda, for example -5V ~ +5V => 0V ~ 3.3V.

[RongShengWang]

   The datasheets (STM32H753ZI) says (P173) - the VREF– s available only on UFBGA176+25 and
TFBGA240+25. 

    Should we specify it when order (STM32H753ZI)?  

    Thanks

[Andrew Neil]

The package type & number of pins is part of the ordering code:

https://www.st.com/resource/en/datasheet/stm32h753zi.pdf#page=348

[RongShengWang]

Thank a lot!!