External Voltage Reference? To get a most accurate ADC result

cyqdtc · ‎2014-10-06

Posted on October 06, 2014 at 09:53

Dear all,

We are trying to use the on-chip ADC of STM32F407. We have read two appnotes, which are AN4073 How to improve ADC accuracy when using STM32F2xx and

STM32F4xx microcontrollers and AN2834 How to get the best ADC accuracy in STM32F10XXX devices.

It is mentioned that using external voltage references may help improve the performance. My question is that is it really necessary to use voltage references? Comparing with filtered LDO outputs, how the performance could be improved?

Thanks a lot.

#adc

chen · ‎2014-10-06

Posted on October 06, 2014 at 10:05

Hi

''It is mentioned that using external voltage references may help improve the performance. My question is that is it really necessary to use voltage references? Comparing with filtered LDO outputs, how the performance could be improved? ''

Depend upon the application you are doing.

Say for instance you are working on a measurement instrument, and the output is directly from the STM ADC, then you need as much of an accurate Vref as possible. Ideally, this need to be defined in a specification.

One of the main advantages of a Voltage reference over a Voltage Regulator is thermal stability (but again you need to specify and choose a good one). That is the V does not drift (much) with changes in temperature of the circuit. FYI be careful with the current draw from V References, they are not meant to supply much current.