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ADC input voltage level shifting 5V to 3.3V??

Question asked by injunear on Apr 9, 2013
Latest reply on Apr 17, 2013 by bigmac

Hello,

 

I have an analog sensor that requires 5VDC and I want to read it into an ADC channel on the KL25Z Freedom Board.


In am providing an external 5VDC to power the board and which also powers the sensor. How might one convert a variable 0-5V range from the sensor into a 0-3V range for the board?


And, do I need to electrically isolate the sensor analog output from the analog input to the MCU? In other words, will a simple voltage divider network work, or is the 3.3V separate and unconnected from the external 5V supply?

 

I have considered the TI AMC1100 but the input voltage range is only about +-300 mV.


To use this, I speculate one could connect the sensor output to a voltage divider network and read the voltage drop across a resistor as the input to the AMC1100 and then run the output into the MCU ADC, but, is there an easier way?


Thank you.


Hillbilly Injunear



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