How to tone down a signal in ST board?

[Vincenzo Di Matteo]

Posted on August 24, 2017 at 17:56

Hi community,

A lot of sensors output go from 0 to 5V. But the ADCs on Nucleo Boards have a 0-3.3V range. The solution is to use some external resistors to reduce the input of the ADC.

Is there another solution without external resistors? I think using 5V tollerant pin, then route the signal somewhere that could tone down the signa and then enter in ADC. Is it possible?

I think about OPAMP but I notice that I can only amplify the signal.

What do you think?

#attenuator #adc

[S.Ma]

Posted on August 24, 2017 at 18:25

Most sensors are high impedence while the ADC requires low impedence, hence an external op-amp with voltage scaling would probably be effective. Using sensor with lower operating voltage be a plus. Ideally, differential sensors with differential input ADC on STM32 may provide better common mode noise reduction.