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PRedd.111
PRedd.111
Associate III
September 30, 2019
Solved

With the ADC using single ended input channel, what is the internal vref, what is the 12 bit voltage range for measurement (is it 0 to 2.5V or 0 to 3.3V)? What is the lowest accurate measurement resolution when we have less than 20mV to measure?

  • September 30, 2019
  • 1 reply
  • 779 views

I am trying to work with photo diodes and need to measure 20mV or less with ADC. Whats the best resolution I can get with a single ended ADC (using ADC 3 channel 12 at the moment).

Whats the measurement range on that channel? When we have less than 10mv, Is the ADC likely to give out a 0 value ?

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Best answer by TDK

Generally VREF is the same as your VDD voltage, which is usually 3 or 3.3v, but it can be lower. Resolution would be VREF/4095. So 0.8mV or so.

10mV should definitely return a nonzero reading for a 12bit sample. Readings near zero are a bit more stable than higher values, but your resolution will be limited.

1 reply

TDK
TDKAnswer
Super User
October 1, 2019

Generally VREF is the same as your VDD voltage, which is usually 3 or 3.3v, but it can be lower. Resolution would be VREF/4095. So 0.8mV or so.

10mV should definitely return a nonzero reading for a 12bit sample. Readings near zero are a bit more stable than higher values, but your resolution will be limited.

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PRedd.111
PRedd.111Author
Associate III
October 1, 2019

Looks like that 0.8mV is true. My VDD is 3.3V and my measurements seems to confirm the same. Thank you.

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